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Laws of nature, cosmiccoincidences and scientificrealismMarc Lange aa University of California , Los AngelesPublished online: 02 Jun 2006.

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Australasian Journal of Philosophy Vol. 74, No. 4; December 1996

LAWS OF NATURE, COSMIC COINCIDENCES AND SCIENTIFIC REALISM

Marc Lange

I. Introduction

Consider an unobservable entity posited by our best scientific theories. For it to be unre-

al, the fact that so many phenomena can be saved by a theory positing it would have to

be a coincidence on a mind-bogglingly cosmic scale, which is very unlikely. So argue

many scientific realists. When, in this connection, realists use an expression such as

'cosmic coincidence', ~ they typically do not explain exactly what it means; it serves to

pump our intuitions. Yet these intuitions must be cashed out, and 'cosmic coincidence'

has a familiar meaning in philosophy: it has long been used to characterize the facts

described by 'accidental generalizations', such as Reichenbach's 'All gold cubes are

smaller than one cubic mile' [28, p. 368]. Accidental generalizations are contrasted with

statements of natural law; both are true, but only law-statements possess 'physical neces-

sity', which enables them to support counterfactuals and scientific explanations in a

characteristic manner. This suggests that according to realists, if an unobservable entity,

P, posited by our best scientific theories is unreal, then 'Any phenomenon o f . . . kind is

as if there were P' is an accidental generalization. (Put slightly differently, this general-

ization is 'Any empirical hypothesis o f . . . kind obtains if that hypothesis would obtain

were the theory positing P true.'2)

So interpreted, the realists' argument is not fully convincing. There are uncountably

many 'coincidences' in the sense of correlations lacking physical necessity. Some of

these concern limited regions of space-time, whereas others (like Reichenbach 's)

describe coincidences on a cosmic scale. There is no obvious reason why the facts to

which realists point - e.g., that so many phenomena can be saved by a theory positing P

- could not also be cosmic coincidences. Indeed, realists concede that many unobserv-

ables that scientists once posited saved a wide range of phenomena but turned out to be

unreal.

Implicit in the realists' argument is the notion that if P is unreal, then it is an accident

that phenomena are as if there were P, whereas if P is real, then 'Any phenomenon o f . . .

kind is as if there were P' is a law-statement. In this paper, I will cash out this intriguing

thought. I will consider whether it contains the germ of an argument for realism that

succeeds where the above argument failed. This new argument exploits the connection

that has often been alleged between believing a hypothesis lawlike and regarding its

1 See, for instance, Smart [33, pp. 25, 39, 47] and Hacking [10, pp. 146f]. The theory positing P determines how the ellipsis is to be filled in; the relevant 'kind' consists of (the hypotheses concerning) the phenomena that, according to the theory, involve Ps. For exam- ple, suppose the Ps are posited as the unobservable constituents of certain observable entities (as when Einstein posited the photon as constituting light). Then the relevant 'kind' consists of the phenomena involving those observable entities. (For the photon, these are phenomena involving electromagnetic radiation, such as the photoelectric effect and the black-body spectrum.)

614

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Marc Lange 615

instances as able to confirm it inductively. Ultimately, I will have to investigate whether

any such connection exists. The argument that has frequently been advanced for it again

turns on the notion of a 'coincidence'. I will have to explicate this sense of 'coinci-

dence' as well as the sense used by realists in referring to 'cosmic coincidences'. And I

will argue that these concepts, and their relations to inductive confirmability and scientif-

ic realism, are useful in rationally reconstructing scientific practice. To make this point,

I will apply these notions to the dispute between Einstein and other physicists from 1905

to 1922 over the photon's reality.

Does P's reality entail that it is no accident, but a natural law, that all phenomena in a

particular range are as if there were P? I will argue that this entailment holds when the

unobservable is posited as constituting a natural kind of entity. Too many discussions of

scientific realism presuppose that it is easy to understand what it would be for a given

posited unobservable to be real rather than a useful fiction. This distinction may be easy

to grasp when the unobservable is supposed to be like a familiar observable entity, only

much smaller. (For instance, Salmon [29, p. 12] considers the punctuation marks in the

compact edition of the Oxford English Dictionary, which are detectable only with a mag-

nifying glass.) But some unobservables posited by science (e.g., the magnetic field or

line of force, the id, the robin's ecological niche, autism) are not supposed to be minia-

ture versions of familiar observable entities; they would be unobservable even if they

were larger or our eyes had greater resolving power. To posit one of them is to posit a

kind of entity of a new sort, i.e., of a sort unfamiliar from observable entities - such as a

kind of force, kind of personali ty component , or kind of disorder. There is no

antecedently familiar conception of what it would be for a kind of entity of that sort to be

real. Rather, I will argue, scientists identify certain kinds of natural laws as obtaining

exactly when a kind of entity of that sort is real.

For instance, Faraday and Maxwell worked to understand what it would take for the

expression 'magnetic line of force' to be more than a formal device for specifying the

'potential' force at various locations. In papers such as Faraday's 'On the physical char-

acter of the lines of magnetic force' (1852), they endeavoured to discover the sorts of

natural laws there would have to be for the magnetic line of force (or any other kind of

line of force) to be real. (For instance, Faraday held that there must be a law specifying

the particular finite velocity by which a change in the field's strength at one location

propagates to alter the field's strength at other locations.) Problems result when it is for-

gotten that there was no antecedently familiar conception of what it would be for such an

entity to be real. For instance, Smart argues that the electric line of force must be a theo-

retical fiction, since physics holds that 2rt lines of force leave a unit charge, but

[it is a] logical impossibility that there could be exactly 2~ lines of force emerging

from it. (There cannot be exactly 2z~ of anything, whether sausages, immaterial souls,

or lines in space!) [33, p. 34]

Smart presumes that to be real, a line of force (or a soul) must in certain basic respects

resemble familiar observable objects. But scientists have worked to ascertain whether

lines of force are real or merely empirically useful, even while fully recognizing that 2~

of them purportedly emerge from a unit charge. It appears that to be real, a line of force

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616 Laws of Nature, Cosmic Coincidences and Scientific Realism

need no more resemble a sausage than an electron need resemble a hard, tiny ball. To

believe that the electric line of force is a real kind of line of force, I will argue, is instead

to believe that there are natural laws of certain sorts.

In my argument, I will appeal to the distinction between a natural law and a cosmic

coincidence. I will need to investigate certain aspects of this distinction, but I will not

try to understand what makes a true generalization express a law rather than a cosmic

coincidence. I have discussed this fundamental question elsewhere; 3 it would take con-

siderable space to defend any answer properly; and I intend my discussion of realism to

presuppose no particular account of lawfulness.

However, at the close of this paper, I will contend that my conception of what it

would be for some novel kind of posited unobservable to be real counts against the view

that a law involves a novel kind of unobservable: a necessary connection. We should

expect my argument regarding realism to have some bearing on necessitarian approaches

to natural law because it begins with the thought that if some posited unobservable, P, is

unreal, then it is a cosmic coincidence if all phenomena in a certain range are as if there

were P. This same thought is implicit in a common argument for necessitarianism: in

Foster's words, we are justified in positing a particular connection of natural necessity,

e.g., the law of gravity,

because it eliminates what would otherwise be an astonishing coincidence: it enables

us to avoid the incredible hypothesis that the past consistency of gravitational behav-

iour, over such a vast range of bodies, occasions, and circumstances is merely

accidental. [8, p. 92]

Realists and anti-realists both seem to regard a regularity's lawfulness as like a special

kind of posited unobservable; van Fraassen [36], [37], for instance, takes the same dim

view of believing that some posited unobservable is real, not merely empirically useful,

as he does of believing that 'All Fs are G' states a law, not merely a truth. In agreeing on

the G-ness of all actual Fs, 'It is a law that all Fs are G' and 'It is an accidental general-

ization that all Fs are G' seem like two empirically equivalent scientific theories.

I will argue that the connection of natural necessity, unlike (say) the electron, is not a

novel kind of unobservable posited by our scientific theories, because the reality of novel

kinds of unobservables consists in nothing other than the fact that certain law-statements

obtain. Rather than positing a special unobservable entity (a 'necessary connection') in

whose ontological status resides a law's lawfulness, I will argue that various laws are

responsible for the reality of novel kinds of unobservable entities.

II. Realism vs. Anti-Realism

Scientific realism is the conjunction of two views. The first conjunct is that if a scientist

holds some opinion about the reality of a posited unobservable, then that belief might

appear in a rational reconstruction of her scientific work. By itself, this first conjunct

leaves matters fairly open, since a belief about the reality of some unobservable can be

3 See Lange [15], [17] and [18].

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Marc Lange 617

that the posit is real, or that it is unreal, or that it may be real, or that it is probably real,

or any other vague or specific degree of confidence in its reality. Which of these beliefs,

according to scientific realism, can have a place in a rational reconstruction of scientific

practice? The second conjunct of scientific realism answers this question: one sort of

belief that a scientist, in doing science, can sometimes be justified in holding is that a

certain posited unobservable is real.

An anti-realist denies one of the two conjuncts constituting realism. She might deny

the first conjunct; she might hold that none of a scientist 's beliefs about the reality of

posited unobservables belongs in a rational reconstruction of her scientific activity. Or

she might accept the first conjunct and deny the second; she might hold that some beliefs

regarding the reality of posited unobservables can appear in a rational reconstruction of

scientific practice, but belief in an unobservable 's reality isn ' t one of them.

An anti-realist of the latter sort might hold that a scientist, in doing science, must

believe certain posited unobservables unreal - namely, those whose reality she believes

to have empirical consequences running contrary to past observations. Regarding any

posited unobservable whose reality is consistent with our observations, this anti-realist

might hold that a scientist qua scientist should believe that it may be real but that it is

probably unreal, considering how many different conceivable unobservables can 'save

the phenomena' . In contrast, van Fraassen [36] is an anti-realist who denies the first of

the two conjuncts that constitute scientific realism. Such an anti-realist holds that a

rational reconstruction of anyone's scientific work is entirely free from beliefs regarding

the reality of some unobservable, whether full-fledged belief (that it is real, that it is

unreal) or some intermediate degree of belief (e.g., that it may be real); qua scientist, she

has no beliefs at all about the reality of various posited unobservables. 4 He thinks that a

scientist may justly hold beliefs concerning a posited unobservable 's reality, even that

the unobservable is real. But he qualifies as an anti-realist because he maintains that a

scientist can hold these beliefs on her own time, but not as a scientist; while these beliefs

might have a place in the 'context of discovery' (e.g., in a psychological history of how

the scientist came to contemplate a certain hypothesis), they have no role to play in a

rational reconstruction of her scientific work. 5 He argues that all of the familiar features

of scientific practice can be captured by interpreting belief in a theory's empirical ade-

quacy as the only belief involved in the acceptance of that theory in science. He argues

that belief in a posit 's reality makes no contribution (except in the 'context of discovery')

to the achievement of science's goal, i.e., performs no function in scientific work.

I will argue against any anti-realism (like van Fraassen's) that rejects the first of the

conjuncts constituting scientific realism. Belief that a given unobservable may be real,

4 Having, qua scientist, no beliefs at all regarding the reality of posited unobservables is not the same as having, qua scientist, some low (but non-zero) degree of confidence in their reality, even neutral sounding beliefs that we might express as 'It may or may not be real - who knows? - we can't be at all confident one way or the other'. This distinction is muddied by characteriz- ing this anti-realist as holding that the scientist qua scientist is 'agnostic ' regarding unobservables. See also fn. 6.

5 I do not mean to suggest that, according to van Fraassen, no mention of this posited unobserv- able would appear in a rational reconstruction of her scientific work. On the contrary, van Fraassen says that while no belief regarding the reality of this unobservable belongs to her scien- tific activity, a commitment to working only with models that incorporate the unobservable is part of accepting a theory positing it.

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618 Laws of Nature, Cosmic Coincidences and Scientific Realism

under taken before we have accepted all o f the empirical consequences of the theory

posi t ing it, f igures in a rational reconstruction o f scientific pract ice because (I will argue)

this bel ief affects how a scientist confirms those empirical consequences . Bel ief that a

posi ted unobservable may be real can be a scientis t ' s reason for regarding a given piece

of evidence as able to conf i rm each empirical predict ion in a certain wide range, because

belief that a given unobservable may be real can be responsible for the inductive con-

firmability of a given hypothesis .

To defeat anti-realism o f van Fraassen ' s sort, it suffices to show that some beliefs

about the reality of unobservables can perform functions that must appear in a rational

reconstruct ion o f sc ience and that could not be per formed i f bel iefs exclusively con-

cerned observables. I will focus on bel ief that a given unobservable may be real, rather

than on bel ief that it is real, because I am interested in the role that bel iefs about the

pos i t ' s reality play in the confirmation of certain empirical consequences of the theory

posi t ing it. All such conf i rmat ion is over as soon as we believe that the posit is real. 6

Furthermore, I will do little to argue that we are somet imes just if ied in believing that

some posit is real, or even that it may be real. I take for granted that science is a rational

activity. Thus, if (as I will argue) bel ief that a posi ted unobservable may be real has a

unique role to play in a rational reconstruction o f scientific work, then I presume that this

Recently, van Fraassen has held that a scientist qua scientist has maximally vague opinions regarding the reality of an unobservable posited by a theory. That is, van Fraassen now repre- sents one 's lacking any opinion regarding the reality of the unobservables posited by an accepted theory not as one's having no degree of confidence at all regarding whether they are real, but rather as one's having a degree of confidence spread out over the interval [0, 1]: [A]cceptance of a theory involves a certain amount of agnosticism, or suspension of belief. (As far as science is concerned, of course; an individual scientist may additionally believe in the reality of entities behind the phenomena• Similarly, a chess player may wear flowers or hum a madrigal while playing.) But can this sort of cognitive attitude be accommodated by probabil- ism? • . . [It is a mistake] to assume that agnosticism is represented by a low probability• That confus- es lack or suspension of opinion with opinion of a certain sort. To represent agnosticism, we must take seriously the vagueness of opinion, and note that it can be totally vague• [37, pp. 193f] He apparently now also holds that a scientist qua scientist believes unreal the unobservables posited by a theory she rejects (as empirically adequate). If van Fraassen's present view is that a scientist qua scientist has a vague degree of confidence in the reality of some unobservable posited by a hypothesis she is entertaining, then, since this vagueness includes some non-zero range, it might initially seem that I am not arguing against van Fraassen when I argue against the view that a scientist qua scientist has no opinions (in the sense of having no degrees of confidence, precise or vague) regarding the reality of posited unobservables. But this interpretation fails to recognize that van Fraassen continues to deny that opinions regarding the reality of posited unobservables have any role to play in a rational recon- struction of scientific practice. I will argue that they have a crucial role to play. Moreover, it seems to me that since van Fraassen recognizes no work in science for (even vague) beliefs about the reality of unobservables, he has no good reason for including these beliefs in a rational reconstruction of a scientist's research. He should say that the scientist qua scientist has no opinion "(in the sense of having no degrees of confidence, precise or vague) regarding the reality of posited unobservables. Why doesn't van Fraassen say this? I cannot tell. Perhaps he believes that one must have some opinion, of vague or precise degree, about every proposition one considers. If this is his motiva- tion, then he could accommodate it by holding that a scientist, outside of science, must hold opinions concerning the reality of posited unobservables. Perhaps van Fraassen has a different motivation. Suppose theory T (which posits unobservable P) makes an empirical prediction that is nut borne out, and the scientist qua scientist rejects T.

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Marc Lange 619

belief can sometimes be warranted. In particular, I will argue that one must believe that

the posit may be real in order for any evidence to confirm certain empirical claims induc-

tively, but I will not try to justify induction. As for moving from some intermediate

degree of confidence in the posit 's reality to full-fledged belief that the posit is real, I see

no reason why this intermediate degree should not rise indefini tely in the face of

favourable evidence, but I will not argue the point here. Likewise, I will argue that to

believe in the reality of certain kinds of unobservables is to believe in natural laws of

certain sorts, while I will take for granted that we can be justified in believing that cer-

tain claims state natural laws.

III. An Argument for Scientific Realism

I will now present my argument for realism. To facilitate its comparison with more

familiar realist arguments, I will initially present my argument in terms of Reichenbach's

'mode l of inferences to unobservab le th ings ' [27, pp. l l 4 f f ] : the cubical world.

Reichenbach argues that a scientist, though trapped inside a cube with translucent walls,

could justify believing in the reality of birds (and a light source and mirrors) outside of

the cube, which are unobservable to her but create shadows on two of the cube 's sides

(Figure 1). Suppose she notices various correlations among the dark shapes that occa-

sionally move across the cube 's ceiling and left wall - e.g., that the appearance on the

ceiling of a shape that looks like the shadow of a short-necked bird is always accompa-

nied by the appearance of a s imilar shape on the left wall. As Salmon [31], [32]

understands the reasoning that Reichenbach ascribes to the cubical-world scientist, her

belief that birds, a light source, and mirrors exist outside the cube is justified because the

theory positing these unobservables best explains correlations among events observed in

the past, correlations that would have been very unlikely were these events statistically

independent.

Continued...

Perhaps van Fraassen concludes that the scientist qua scientist must then believe P unreal, so at least some beliefs about the reality of unobservable entities belong to scientific practice. (And the motivation might continue: it would be odd for scientists qua scientists to believe that vari- ous unobservables are unreal but to have no beliefs, even maximally vague ones, regarding the reality of the unobservables posited by theories that have not been rejected.) But this motivation does not convince me. Admittedly, if a scientist qua scientist rejects T as empirically inadequate, she must believe that P (at least as described by T) is unreal. But why must she adopt this belief qua scientist? Why can't this belief be required of her as a 'private cit- izen ' ? In reply, it might be suggested that if F logically entails G and her belief that F is part of her sci- entific work, then her belief that G must also belong to her scientific work. But I do not accept this principle. A scientist who qua scientist accepts Einstein's theory is thereby committed to believing that either Einstein's theory is empirically adequate or lying is morally wrong, but I see no reason to regard her as believing in this disjunction qua scientist. Likewise (to pick up van Fraassen's example), whether a chess player is humming a madrigal is immaterial to her activities qua chess player (unless, I suppose, she is disturbing her opponent). Of course, a chess player must at some moment either be humming a madrigal or not. But it does not follow that qua chess player, she is in a maximally vague state 'between' humming and not humming a madrigal; rather, there is no (even vague) humming state that she occupies qua chess player.

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620 Laws of Nature, Cosmic Coincidences and Scientific Realism

. . . . . . . . . - - . . . . . . . - - - - w ========================= I I i i : , , .~ '

/ ! , I i

Z. 7 L .... ",- ........... . ..' .__' ' , , ,

!

'~- , - . . . . . . . . r . . . . . . . . . 4 \ ! | I I I i i I |

~ < - , , - . . . . . . . . . . . . . . .

1 I

I

!

I I

- L ~ J ~

h Fig. 1. A cubical world where only the shadows of external things are visible.

To better understand this argument, it helps to ask: what is the significance of how

improbable these correlations would be if the correlated events were statistically inde-

pendent? As Reichenbach emphasizes [27, pp. 122f], realists and anti-realists agree that

the cubical-world scientist is justified in believing that these events are not statistically

independent - i.e., that a correlation among shapes observed in the past was not mere

chance, but obtained as a matter of natural law. Reichenbach holds that a scientist who

believed the correlated events to be statistically independent would have to believe these

correlations unlikely to persist. But even anti-realism permits the scientist to regard the

evidence as confirming the correlations inductively - i.e., as confirming, for each unex-

amined dark shape, that it conforms to the correlations. (Later I will cash out 'inductive'

confirmation more carefully.) Reichenbach contends [28, pp. 359ff, esp., p. 368] that

one can confirm 'All Fs are G' inductively, by discovering an instance (that a given F is

G), only if one believes that the generalization is ' lawlike' - i.e., that if it is true, it is a

law-statement. (Why does Reichenbach think that you cannot inductively confirm a

hypothesis that you believe to be an accidental generalization if true? I will shortly turn

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Marc Lange 621

to this question.) Since realists and anti-realists permit the scientist to believe with justi-

fication that the correlations will continue to hold, they must permit the scientist to

believe with justification that the correlations are lawlike.

Reichenbach's objection to anti-realism is not that it interprets scientists as believing

in many improbable coincidences among statistically independent facts; according to

Re ichenbach , this is not the an t i - r ea l i s t ' s r econs t ruc t ion of science. Rather ,

Reichenbach's point is that scientists try not only to predict empirical correlations, but

also to explain them, and therefore need to posit unobservables. 7 However, anti-realists

do not agree that explanation is a goal of science; they regard science as aiming for

empirically adequate theories, not for theories that also can explain our observations.

Therefore, Reichenbach leaves anti-realists unpersuaded.

The dispute between realism and anti-realism is inconclusive - until it is recognized

that the anti-realist's objection to Reichenbach's argument is inapplicable to a different

argument for realism. That argument exploits Reichenbach's thesis about inductive con-

firmability and lawlikeness (amended to permit intermediate degrees of confidence in a

claim's lawlikeness): we can confirm a correlation inductively only if we believe that it

may be lawlike. In section IV, I will examine this thesis, consider objections to it, and

refine it. For now, I will argue'that if some thesis along these lines is correct, then it can

be used to persuade anti-realists, even granting their austere conception of science's

goal, to adopt the realist's view that a scientist's beliefs about the reality of posited unob-

servables can figure in a rational reconstruction of her scientific work.

A cubical-world scientist notes correlations among the dark shapes that she has

observed on the cube's surfaces. She regards these correlations as strongly confirmed to

hold of unexamined shapes. Moreover, she finds that all of these correlations are among

those that would obtain if these shapes were shadows of unobservable birds. She real-

izes that there may be correlations that she hasn't noted because, as yet, no instances of

them have been observed. For instance, suppose she envisages unobservable birds as

similar to birds she has observed living inside the cube. She knows that a bird occasion-

ally loses certain tail feathers and then flies oddly. But she hasn't yet seen any dark

shapes on the cube's surfaces that took like shadows of birds lacking these tail feathers,

so she hasn't found instances of a correlation between a shape's having this appearance

and its moving oddly.

Considering that the correlations already detected are among those that would obtain

if the shapes were shadows of unobservable birds, the scientist might contemplate what

her view would be if she found that

(*): Any empirical hypothesis concerning the dark shapes on the cube's walls is

true if that hypothesis would obtain were the shapes the shadows of unobserv-

able birds (and were there unobservable mirrors etc., as posited by the theory).

(This is the sort of generalization I discussed in section I.) The cubical-world scientist

might believe that if (*) turns out to be true, then it is a coincidence, an accidental gener-

7 According to Salmon, the anti-realist regards the correlations as 'simply brute facts' [31, p. 142] and as 'improbable chance coincidences' [32, p. 246]. This can be misunderstood; the anti-real- ist regards them not as physically unnecessary, but as like the most basic natural laws in having no explanation of a certain kind.

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622 Laws of Nature, Cosmic Coincidences and Scientific Realism

alization; the relevant natural laws and initial conditions just happen to fit together to

yield the very same empirical facts involving the dark shapes that unobservable birds

would have produced. Alternatively, she might believe that (*) may be lawlike, i.e., that

(*) may state a law? That is, she might believe that if the shapes behave in all respects

as if they are shadows of unobservable birds, it might be no coincidence, for it might be

that the shapes are shadows of unobservable birds. Hence, a scientist 's belief that (*) may be lawlike is intuitively associated (in a man-

ner I will have to elaborate) with a belief that the posited unobservable birds may be real.

And, by Reichenbach 's thesis about lawlikeness and inductive confirmability, a scientist

who confirms (*) inductively must believe that (*) may be lawlike. Thus, a scientist 's

belief regarding the reality of posited unobservable birds influences whether she is justi-

fied in confirming (*) inductively - that is, in taking any hypothetical correlation that she

bel ieves would hold of the dark shapes were there unobservable birds, even if no

instances of it have yet been observed, and regarding it as confirmed by the correlations

that have been ascertained, because they would obtain if there were unobservable birds.

Here is a consequence of believing an unobservable real that is not a consequence of

believing it useful and that is relevant to activities that, realists and anti-realists agree,

belong to science. A scientist who believes some unobservable real may sometimes be

justified in predicting exactly the same observations as a scientist who sticks to beliefs

about observables. But the former scientist can treat those predictions as deriving some

of their warrant from discoveries that the latter must consider irrelevant.

For instance, suppose a cubical-world scientist believes it entirely coincidental if the

various correlations among dark shapes are all just as if there were unobservable birds.

Then presumably she must wait until Sh"~ observes shapes without 'tail feathers' before

accepting a hypothetical correlation involving them that would obtain were there unob-

servable birds; she can ' t regard that correlation as confirmed by the correlations already

detected in virtue of the fact that these correlations also follow from positing unobserv-

able birds. For her to regard the hypothetical correlation as so confirmed would require

her to regard (*) as able to be inductively confirmed, which (by Reichenbach's thesis, to

be examined further in section IV) would require her tO believe that (*) may be lawlike

rather than coincidental, which (as I will examine further in section VI) would require

her to believe that there may really be unobservable birds. 9

8 Why may be lawlike? In order to create two mutually exclusive, collectively exhaustive options. The first option is to believe that (*) is an accidental generalization if (*) is true. If you don't take this option, you might believe that (*) is lawlike (i.e., states a law if true) but you might not; you might have some non-zero confidence in (*)'s lawlikeness that falls short of full belief. So the second option must be to believe that (*) may be lawlike. Also, note that even ff (*) states a law, it does not follow that all of those (true) empirical hypotheses about the shapes are laws. Some uniformities just happen (i.e., as a matter of physically unnecessary fact) to hold of the shapes. For instance, suppose it happens that at 10:30 p.m. on April 23rd of each year divisible by 371, there is a shape o f . . . kind on the left wall. If the shapes are indeed shadows of unob- servable birds, a hypothesis stating this accidental uniformity falls within (*)'s scope (since from the fact that this uniformity holds and the shapes are shadows of unobservable birds, it fol- lows that this uniformity would hold were the shapes the shadows of unobservable birds). But the cubical-world scientist's background beliefs regarding birds, mirrors, etc. - acquired from her experience of these objects inside the cube - would not enable her to anticipate that such a uniformity would hold were the shapes the shadows of unobservable birds.

9 This argument might usefully be compared to Hempel's [11, pp. 214ff] argument in 'The Theoretician's Dilemma'. Hempel maintains that the use of theoretical terms may create 'induc-

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Marc Lange 623

A cubical-world scientist uses unobservable birds to explain correlations among her

observations. This fact doesn't persuade anti-realists to regard her belief concerning the

reality of unobservable birds as belonging in a rational reconstruction of her scientific

activity. That is because anti-realists don't take explanation to be a goal of science.

Anti-realists regard empirical adequacy as science's goal. Accordingly, their rational

reconstruction of scientific practice includes the confirmation of empirical hypotheses.

But (I have just argued) a scientist's degree of belief concerning some posited unobserv-

able's reality affects the range of evidence that she can justly regard as confirming a

given empirical hypothesis. Therefore, to defend the realist's view that beliefs about the

reality of unobservables belong in a rational reconstruction of scientific practice, one

need not consider the goal of science to be the description of reality or the explanation of

observations. Even if one interprets science as directed merely towards empirical ade-

quacy, one must include a scientist's beliefs about the reality of unobservables in a

rational reconstruction of her scientific activity.

One might object that it is inappropriate to confirm (*) inductively by (say) allowing

observations of shapes with 'tail feathers' to confirm a correlation exclusively concern-

ing shapes without 'tail feathers', since this would be to allow evidence having nothing

to do with this correlation to confirm it. Although I am not going to try to justify induc-

tion, I think that the right attitude to take towards this objection is to join van Fraassen in

recognizing that rationality allows a scientist some latitude to take risky gambles.

Consider the correlation involving shapes missing 'tail feathers'. It is rational for a sci-

entist to regard this correlation as confirmed only by observations of such shapes. It is

likewise rational to regard this correlation as confirmed by instances of any other corre-

lation that would obtain were the shapes actually the shadows of unobservable birds. In

electing to gamble on predictions about shapes lacking 'tail feathers', made before hav-

ing observed any such shapes, the scientist takes a greater risk of making inaccurate

predictions while playing for a greater reward (in currency that anti-realists respect):

accurate predictions, from the same evidence, of a broader range of phenomena. I see no

reason to believe that rationality imposes some particular right way to trade off such risk

against the prospect of such reward. Whether the riskier strategy will pay off cannot be

known in advance, but as scientific practice bears out, scientists are entitled to select it.

(In section IV, I will return to this point.) 1°

Continued...

rive systematization', thereby allowing one of the theory's empirical consequences to confirm another. Likewise, I contend that a scientist's belief that a posited unobservable may be real affects the range of evidence that she can treat as confirming one of the theory's empirical claims. But Hempel cannot defend his contention along the lines I advance, since Hempel [11, p. 176 fn. 6, p. 356] denies Reichenbach's thesis linking inductive confirmability to lawlikeness. Indeed, as Salmon [30, p. 123] notes, it is hard to see precisely how Hempel argues for his con- tention. Consider a further objection. I have suggested that a scientist is entitled to regard any empirical hypothesis that (she justly believes) would obtain, were the theory positing P true, as confirmed by any other such hypothesis. It follows that merely by tacking onto the theory a further empiri- cal hypothesis having nothing to do with the original theory, the scientist becomes entitled to regard that hypothesis as confirmed by any of the empirical hypotheses that she believes would obtain were the original theory tree. Isn't confirmation then trivialized, since any empirical hypothesis can be regarded as confirming any other? NO, for three reasons. First, I don't allow a scientist to regard a discovery as simultaneously confirming each other empirical hypothesis

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624 Laws of Nature, Cosmic Coincidences and Scientific Realism

Anti-realists might plead that because of underdetermination, it would be a miracle if

a useful posit were real. But, I have argued, one who believes that it is a coincidence if

all phenomena are as if a given posit were real must impose severe limitations on the

capacity of evidence to confirm empirical correlations, a blow to activities that anti-real-

ists regard as just i f ied and essential to science. Indeed, an anti-realist typically

recognizes numerous historical episodes in which a scientist constructs a grand theory

involving unobservables and thereby becomes entitled to treat many empirical hypothe-

ses as confirmed by evidence that would otherwise have seemed remote from them.

These are among the exemplars of scientific achievement (one of which, Einstein's work

on the photon, I will discuss in section V). These scientists are justified in so confirming

their hypotheses, but (I have argued) only because they believe that certain unobserv-

ables may be real.

IV. Inductive Confirmability and Coincidences

The above argument depends heavily on the concept of a ' co inc idence ' and on

Reichenbach's thesis that we can confirm a generalization ' inductively ' only if we

believe that it may be lawlike. I will now cash out these notions and investigate whether

they can bear the necessary load.

Views similar to Reichenbach's have been advanced by Peirce [25, p. 66], Moore

[23, p. 12], Braithwaite [1, pp. 467, 473], Kneale [14, p. 65], Strawson [34, pp. 199f],

Goodman [9, pp. 20-22], Mackie [20, pp. 71-73], and Dretske [4, pp. 256-260], among

others. Their motivation seems to be the intuition that a 'coincidence' cannot be con-

firmed inductively; to project a uniformity in examined cases onto unexamined cases, we

must believe it 'no accident' that the uniformity has held so far. For example, 'All gold

cubes are smaller than one cubic mi le ' is an accidental generalization because it

describes a 'coincidence': typically, the reason why a given gold cube is smaller than

one cubic mile (e.g., when and where it formed, there wasn't that much gold) has noth-

ing to do with the reason why some other gold cube is smaller than one cubic mile (e.g.,

when and where it formed, remote from the first cube, there wasn't that much gold).

This example suggests that whenever we believe that some generalization describes a

cosmic coincidence if it is true, we should consider it utterly coincidental if the general-

ization has held in all cases already examined, and l ikewise coincidental if the

generalization, having held in all cases already examined, turns out also to hold in a

given, as yet unexamined case. Thus, we cannot ascertain that the generalization holds

in a given unexamined case until we examine that case. In contrast, a law-statement

Continued...

since, for example, H and not-H cannot simultaneously be tacked onto the theory. Second, while I allow that a scientist is entitled to tack any empirical hypothesis onto the theory (so long as the expanded theory remains logically consistent) and to regard that hypothesis as con- firmable by any other empirical consequence of the theory, the scientist is merely entitled, not compelled to pursue this strategy. (Entitlement and compulsion are two fiavours of justifica- tion.) By this tacking manoeuvre, she elects to take a bigger gamble, which presents greater risks while offering the opportunity for greater rewards. Third, the scientist pursuing this induc- tive strategy does not believe that the tacked-on claim has nothing to do with the original theory. She believes that it may be a law that (roughly speaking) all of the empirical consequences of the expanded theory obtain.

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Marc Lange 625

does not describe a coincidence; each of its various cases conforms to it for the same

reason (because the law says that it must). Therefore, when we discover that a given

case conforms to a hypothesis that we believe lawlike, we can confirm that the 'common

cause' obtains and thereby confirm, of each unexamined case, that it conforms to the

hypothesis. Hence, instances of a hypothesis believed lawlike can confirm its truth

inductively, allowing the putative law-statement to be used for making predictions. So

runs the rough intuition.

To explain why lawlikeness supports one instance's relevance to another, we would

have to determine what lawlikeness is. This task is a difficult one; Goodman taught us

that there is no syntactic criterion for lawlikeness. Fortunately, I don't need to pursue

this task here; my aim is not to explain why lawlikeness supports one instance's rele-

vance to another, but rather to argue that it does. Indeed, my task is even more modest -

merely to show that the alleged connection between lawlikeness and inductive confirma-

bility cannot be overturned by apparent counter-examples.

For instance, astronomers believe that i f 'Al l years of maximum solar activity

between 1000 A.D. and 3000 A.D. occur at eleven-year intervals' is true, then it is an

accidental generalization. Yet astronomers regard this generalization's past instances as

confirming, of each solar maximum through (at least) 3000 A.D., that it will occur

eleven years after the previous solar maximum. Cases like this apparently conflict with

Reichenbach's thesis. But on closer inspection, they turn out to be entirely compatible

with the motivation (given above) for maintaining that we cannot inductively confirm a

hypothesis that we believe to be an accidental generalization if true. An accidental gen-

eralization is a cosmic coincidence, and yet it can be no coincidence that a given

examined case and a given unexamined case both conform to the generalization. This

sounds paradoxical, but consider another example.

Anthropologists believe it an accidental generalization that all persons descended

entirely from Native Americans have blood type O or A. Anthropologists believe that all

Native Americans are descended entirely from a single small company that crossed the

Siberia-Alaska land bridge and, as it happened, no one in the company possessed allele

B. So for any unexamined Native American, it is no accident that both she and an exam-

ined Native American both conform to the generalization, considering their common

descent.

Anthropologis t s began their research with the be l ie f that perhaps all Native

Americans are descended from the same stock; that is, they believed from the outset that

although the hypothesis 'All Native Americans have blood type O or A ' is non-lawlike,

it may be no coincidence that both an examined Native American and any actual unex-

amined Native American conform to it. Consequently, anthropologists who checked

many Native Americans, and found each to have blood type O or A, thereby confirmed

of any actual unexamined Native American that she conforms to the hypothesis.

Nevertheless, anthropologists believed this hypothesis non-lawlike; they believed it

physically unnecessary (coincidental) that all Native Americans are descended from the

same small company.

It is conceivable - it is an unactualized physical possibility - for two companies of

migrants to have crossed the land bridge. It would then have been a coincidence if both

companies had lacked allele B. When anthropologists regard an instance of the hypothe-

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626 Laws of Nature, Cosmic Coincidences and Scientific Realism

sis 'All Native Americans have blood type O or A ' as confirming, of each unexamined

case believed actual, that it conforms to the hypothesis, this confirmation depends on the

anthropologists' beliefs about which conceivable unexamined cases not believed physi-

cally impossible happen to be actual. In particular, anthropologists must not believe that

a given unexamined Native American descends from a different band of migrants from

the Native American under examination, for the discovery that the examined case lacks

allele B would then fail to confirm that the unexamined case lacks allele B; anthropolo-

gists believe that it would be coincidental for these two Native Americans both to lack

allele B. In short: even if we believe that 'All Fs are G' is an accidental generalization if true,

we can believe that for any two actual Fs, it is no accident if both are G. But we must

believe that for some pair of conceivable Fs that are not physically impossible, it is coin-

cidental if both turn out to be G. For this reason, we cannot confirm the generalization

inductively. Consider our earlier example. That past solar maxima have occurred eleven years

apart confirms that solar maxima in the near future will occur at eleven-year intervals.

But this confirmation goes through only because we have some confidence that as a mat-

ter of (physically unnecessary)fact, the sun's internal constitution will remain roughly

the same in the near future. These instances don't confirm that the next solar maximum

would occur 'on schedule' were there meanwhile a dramatic and unprecedented change

in the sun's colour, brightness, size, etc. To put the point generally: an instance of a hypothesis believed non-lawlike may

confirm, of each unexamined case believed actual, that it conforms to the hypothesis.

But this confirmation occurs only by grace of some background beliefs regarding which

conceivable unexamined cases not believed physically impossible happen to exist. In

other words, the instance doesn't confirm, of each conceivable unexamined case not

believed physically impossible, that it conforms to the hypothesis. 11

In the above examples, an instance of a hypothesis confirms, for any unexamined

case believed actual, that it conforms to the hypothesis. In this respect, the confirmation

in these .examples (involving hypotheses believed non-lawlike) is similar to inductive

confirmation - i.e., to the sort of confirmation that (according to many philosophers) is

reserved exclusively for hypotheses that we believe may be lawlike. But the confirma-

tion in the above examples is not inductive confirmation. When a hypothesis is

confirmed inductively, the instance's relevance to unexamined cases doesn't depend (as

it does in the above examples) on background beliefs about which conceivable unexam-

ined cases, among those not believed physically impossible, happen to be actual. For

example, Newton saw his evidence for the gravitational-force law as confirming, for

each unexamined pair of material point particles at each moment, that its members exert

a given gravitational force on each other. The reason Newton construed the evidence as

relevant to each actual unexamined pair of point masses wasn't that Newton believed the

evidence relevant to any unexamined pair of point masses that happens to have a certain

This is closely related to the fact that accidental generalizations don't support counterfactuals in the manner of laws; in confirming that all Native Americans lack allele B, anthropologists don't confirm that the Native Americans who would have descended entirely from a conceivable sec- ond company of land-bridge migrants would also have lacked allele B.

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Marc Lange 627

feature, and that it is an accidental generalization that all pairs of point masses through-

out the universe's history have this feature. He believed the evidence relevant to each

unexamined pair of point masses there is because he believed it relevant to each unexam-

ined pair of point masses there might be. He saw the evidence as relevant to any

prediction made by the gravitational-force law just because the evidence and the predic-

tion both concern pairs of point masses. That is, he appeals to his Third Rule of

Reasoning, a principle of the uniformity of nature. I take this to be inductive confirma-

tion (and take Newton to have been entitled to elect this bold strategy).

By deeming non-inductive the anthropologists' confirmation of their hypothesis, 1

mean to recognize an important distinction. When an instance confirms 'All Fs are G'

and bears upon each thing we believe to be an actual unexamined F, it does so for one of

two reasons: either simply because the examined case and each unexamined case are

both Fs, as with Newton, or because of background beliefs about which of the conceiv-

able unexamined Fs that may be physically possible actually happen to exist, as with the

anthropologists. I believe I am onto the intuition that motivated Reichenbach and so

many others to connect lawlikeness and inductive confirmability. Accordingly, I stipu-

late that an instance confirms a generalization 'inductively' exactly when the instance

confirms, for (roughly speaking) each conceivable unexamined case not believed physi-

cally impossible, that it conforms to the generalization.

The range of conceivable unexamined cases that an instance confirms to conform to

the hypothesis, when it confirms the hypothesis inductively, must be stated more precise-

ly. Indeed, it must be explained what it means to confirm something about a case when

we believe that the case doesn't exist. In my [17], and more fully in my [19], I address

these points. I use the probability calculus to define 'inductive' confirmation more pre-

cisely, and I show how it follows that we can confirm a generalization inductively only if

we believe that it may be physically necessary. While it is obviously crucial to my argu-

ment that the distinction between inductive and non-inductive confirmation be capable of

being drawn rigorously, nothing that I say here will depend on the details of the more

careful characterization that I give elsewhere. I appeal here only to the intuition that

motivated Reichenbach and others to see inductive confirmability as presupposing law-

likeness; I have tried to show that this intuition cannot be dismissed easily.

On my version of Reichenbach's thesis; a cubical-world scientist can confirm (*)

inductively only if she believes that (*) may be physically necessary. But does physical

necessity entail lawlikeness? As I discuss in my [15] and [16], I don't believe it does.

Some generalizations, such as 'All signals travel slower than twice the speed of light'

and 'All emeralds in my pocket are green', do not seem to me to state natural laws them-

selves, though they are true entirely in virtue of natural law. I wouldn't feel compelled

to respect this intuition if there was no evidence that science recognizes a distinction

between the laws and the non-lawlike physical necessities. But such a distinction is pre-

sent in scientific practice: some physical necessities are deemed 'coincidental' (again

that term!), which suggests that they are considered non-tawlike. Can we inductively

confirm a hypothesis where we believe that if it is true, then it is physically necessary but

coincidental?

Here is a historical example. Hypotheses positing patterns in the atomic weights of

various chemical species were once considered lawlike (see [38, pp. 73f]). For instance,

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628

it was believed that

Laws of Nature, Cosmic Coincidences and Scientific Realism

(H): All differences between the atomic weights of alkane radicals (i.e.,

methyl, ethyl, etc.) are multiples of 14 ainu

and

(N): All nitrogen atoms have an atomic weight of 14 amu

are law-statements. But it was held (e.g., by von Pettenkofer) that

(HN): All differences between the atomic weights of alkane radicals are

multiples of the atomic weight of any nitrogen atom

is mere 'coincidence,' not a law-statement, x~

What did chemists mean by deeming (HN) a 'coincidence'? The presence of two old

friends in the same restaurant simultaneously is 'coincidental' only if there is no com-

mon cause (e.g., their having arranged to meet there); the explanat ion of their

simultaneous presence consists of an explanation of the first friend's presence plus an

unrelated explanation of the second's. Likewise, chemists deemed (HN) coincidental,

albeit physically necessary, because its explanation, although composed entirely of law-

statements, contains no law-statement concerning both nitrogen atoms and hydrocarbon

radicals; roughly speaking, (HN) is coincidental because it arises from the way that two

unrelated law-statements, (H) and (N), fit together. 13

This intuitive understanding of why (HN) was deemed coincidental is obviously

incomplete; I have not specified what makes (H) and (N) 'unrelated' law-statements. To

give necessary and sufficient Conditions for a claim to qualify as physically necessary

but non-lawlike is beyond the scope of this paper; it is part of the general problem of

explicating the concept of natural law. Here I am concerned instead with the role of

physical necessity and inductive confirmability in my earlier argument regarding scien-

tific realism. Once we recognize that some physical necessities are non-lawlike, we

notice that we may be able to confirm a hypothesis inductively even if we believe it non-

lawlike, so long as we believe that it may be physically necessary. For example, suppose

we discover an instance of 'All emeralds in my pocket are green'. In so doing, we dis-

cover an instance of 'Al l emeralds are green'. Intuitively, if the instance ( 'c is an

emerald and green') of the lawlike hypothesis confirms it inductively, then the instance

That (N) and (H) were believed to function as law-statements in connection with scientific explanations, although their logical consequence (HN) was not, is reminiscent of Hempel and Oppenheim's famous note [11, p. 273 fn. 33] that the conjunction of Boyle's and Kepler's Laws can do no explanatory work. Classical astronomers, such as Hipparchus and Theon of Smyrna, apparently also recognized physically necessary coincidences. If a planet's natural component motions are along an eccen- tric circle with a moving centre, then (these astronomers say) a hypothesis that decomposes the planet's orbit into a different set of components - e.g., into epicyclic and deferential motions - agrees 'accidentally', yet entirely in virtue of a geometric theorem, with the resultant of its nat- ural motions. See my [16].

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Marc Lange 629

( 'c is an emerald in my pocket and green') of the non-lawlike hypothesis likewise con-

firms it inductively. The rough idea is that every conceivable unexamined case of the

non-lawlike hypothesis that must be confirmed to be green, for that hypothesis to be con-

firmed inductively, is confirmed to be green when the lawlike hypothesis is confirmed

inductively? 4

The important issue here for our argument regarding scientific realism is whether a

cubical-world scientist could confirm (*) inductively without believing that (*) may be

lawlike (and so without believing that the posited unobservable birds may be real) -

because she believes that (*) may be physically necessary. To address this question, let

us examine whether we can inductively confirm a hypothesis that we believe non-law-

like, where we believe it may be physically necessary, but where (unlike 'All emeralds in

my pocket are green') we believe the hypothesis coincidental if true, i.e., there is no sin-

gle claim that entails it and that we believe may be lawlike.

Presumably, chemists confirming (HN) believed that if (HN) is physically necessary,

it is not made physically necessary by any single law-statement, but rather by two law-

statements - perhaps (H) and (N). Moreover , chemists bel ieved that if (HN) is

physically necessary, it expresses a coincidence, but it is no coincidence that an exam-

ined case and an unexamined case both conform to (HN). Rather, there is a 'common

cause'. Indeed, two causes are common to the two cases: (H) and (N); each of (HN)'s

instances is explained by the same pair of law-statements. Recall that 'All emeralds in

my pocket are green' can be inductively confirmed through the inductive confirmation of

'All emeralds are green', the 'common cause'; we believe that 'All emeralds are green'

may be lawlike and may be responsible not only for the greenness of the examined emer-

ald from my pocket, but also for the greenness of an unexamined emerald from my

pocket. Likewise, chemists could confirm (HN) inductively, but only through the induc-

tive confirmation of a possible 'common cause', i.e., a hypothesis that they believed may

be lawlike, may be partially responsible for the examined case's conforming to (HN),

and may be partially responsible for the unexamined case's conforming to (HN). So

chemists could confirm (HN) inductively through inductively confirming (H) or induc-

t ive ly conf i rming (N). With this I am con t inu ing to cash out the not ion of a

'coincidence' figuring in Reichenbach's thesis that a cosmic coincidence cannot be con-

firmed inductively.

Now consider a hypothesis (such as 'All emeralds and rubies are green if emeralds

and red if rubies') where we believe that if it is true, it is physically necessary, non-law-

like, and (unlike (HN)) there is no undiscovered law that is partially responsible, alike in

every case, for that case's conforming to the hypothesis. In particular, we believe that if

this hypothesis is true, then no single undiscovered law is partly responsible both for an

emerald's greenness and for a ruby's redness; unlike the situation with (HN), there is no

'common cause'. So if the evidence concerns an emerald and the unexamined case is a

ruby, or vice versa, it is a coincidence if both conform to this hypothesis. Therefore, evi-

dence cannot confirm this hypothesis inductively; for any examined case, there is a

To cash this out properly, I would need the precise characterization of 'inductive' confirmation in my [17] and [19]. Further necessary conditions are satisfied when (e.g.) we believe that 'All emeralds in my pocket are green' is physically necessary only if 'All emeralds are green' is physically necessary.

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630 Laws of Nature, Cosmic Coincidences and Scientific Realism

conceivable unexamined case, of the sort that we must confirm to agree with the hypoth-

esis in order for the examined case to confirm the hypothesis inductively, such that it

would be a coincidence for the examined and the unexamined cases both to agree with

the hypothesis.

In the above examples, scientists confirm hypotheses that they believe non-lawlike

but perhaps physically necessary. These examples suggest that we confirm hypothesis H

inductively only by inductively confirming a hypothesis L that we believe may be law-

like, where we be l ieve that i f L and H are physical ly necessary, then for each

conceivable unexamined case C of H that (roughly speaking) we do not believe physical-

ly impossible , L may be part ial ly responsible for the physical necessi ty of C 's

conforming to H. Such an L would then be a 'common cause' of H's various cases con-

forming to H; in virtue of L, it would - for any examined case and any unexamined case

- be no coincidence that they both conform to H.

Suppose a cubical-world scientist believes that (*) is non-lawlike but may be physi-

cally necessary. Then she may be entitled to regard (*) as inductively confirmed by a

correlation that (she believes) would obtain were the shapes the shadows of unobservable

birds. But for her to be so entitled, there must be a hypothesis L that she believes may be

lawlike and is inductively confirmed, where she believes that if L and (*) are physically

necessary, then (roughly speaking) for each conceivable undiscovered correlation C that

would obtain if the shapes were shadows of unobservable birds, L may be partly respon-

sible for C's obtaining. Considering the diversity of the correlations that would obtain if

there were unobservable birds, it would be surprising if cubical-world scientists pos-

sessed a hypothesis L identifying a plausible 'common cause' of their all obtaining -

other than the hypothesis that there are unobservable birds. So scientists can confirm (*)

inductively only if they believe it may be lawlike (and so only if they believe that the

posited unobservable birds may be real).

V. An Example: Einstein's Work on the Photon

I 've used Reichenbach's example of the cubical world to illustrate the consequences, for

the confirmation of empirical predictions, of a belief that some posited unobservable

may be real. This is a fictitious example. I should consider actual historical episodes

and argue that, for the reasons I have suggested, the best way to rationally reconstruct

them is to interpret some scientists as believing from the outset, and others as denying,

that some posited unobservable may be real. I will now briefly examine one such

episode.

After 1905, the accuracy of Planck's black-body equation became widely accepted.

Planck had shown that this equation could be derived by using the premise that energy is

exchanged in discrete units between material resonators and the radiation field.

Beginning in 1905, Einstein considered the possibility that Planck's posited energy-

quantum was real and elaborated its consequences for the interaction between light and

matter. In 'On a heuristic viewpoint concerning the production and transformation of

light' [5], Einstein showed that Wien's radiation law (which approximates Planck's at

high frequencies and low temperatures) implies that black-body radiation behaves (with

respect to its entropy's dependence on volume, for fixed energy) as if it were an ideal gas

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Marc Lange 631

of particles. In 1906, Einstein showed that the energy possessed by each of these parti- cles is equal to hv, the energy of Planck's quantum. Einstein maintained [6, p. 199] 'that Planck's theory makes implicit use of the light-quantum hypothesis'.

Einstein might have held that although the light-quantum is useful for deriving empir- ically adequate generalizations concerning the black-body spectrum and the black-body radiation's entropy, this is just a coincidence, i.e., 'nothing more than a curious property of pure radiation in thermal equilibrium, without any physical significance' (Pais [24, p. 377]). Recall the analogous stance concerning (*); I have argued that Einstein would then have had no reason to expect that other phenomena involving electromagnetic radia-

tion are also just as they would be were light composed of photons. Einstein, however, held that the photon may be real and, therefore, that if this posit turns out to be widely useful, its utility may be no coincidence. Accordingly, he saw the fact that Planck's empirically adequate equation could be derived from the light-quantum hypothesis as evidence, regarding any other phenomenon involving light, that it is governed by equa- tions derivable by treating light as particles. In the title of his [5], Einstein emphasized the function of the light-quantum hypothesis as 'a heuristic viewpoint', a strategy on which he had elected to gamble.

Most physicists were unwilling to consider the possibility of the photon's reality. Typical was Planck's 'semi-classical' view: that quantum considerations govern the emission and absorption of radiant energy through the processes by which a black body comes into equilibrium with the radiation field, whereas radiation exchanging energy with matter in other ways (e.g., by the photoelectric effect) or freely propagating (e.g., in interference phenomena) should be understood as continuous electromagnetic waves (D'Abro [3, p. 463]; cf. Stuewer [35]). It would then be merely coincidental if many phenomena besides black-body radiation could be saved by using the photon hypothesis. Only Einstein, Ehrenfest and yon Laue were applying the photon to all interactions of light and matter. In 1905, Einstein derived from the light-quantum hypothesis an equa-

tion for the photoelectric effect. He also derived Stokes's rule of photoluminescence and applied the light-quantum hypothesis to the Volta effect. In 1907, he applied the hypoth- esis to the specific heat of solids; he declared that the light-quantum's empirical utility in connection with the black-body spectrum confirms its utility in connection with other thermal phenomena:

If the elementary oscillators that are used in the theory of the energy exchange between radiation and matter cannot be interpreted in the sense of the present kinetic molecular theory, must we not also modify the theory for the other oscillators that are used in the molecular theory of heat? There is no doubt about the answer, in my opinion. If Planck's theory of radiation strikes to the heart of the matter, then we must also expect to find contradictions between the present kinetic molecular theory and experiment in other areas of the theory of heat, contradictions that can be resolved by the [light-quantum]. [7, p. 184]

In 1909, he elaborated the photon's consequences for the generation of secondary cath-

ode rays by X-rays. In 1911, he used it to derive the high-energy l imit for Bremsstrahlung. In 1912, he discussed its application to photochemical processes. One

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632 Laws of Nature, Cosmic Coincidences and Scientific Realism

would not regard the mere fact that a given hypothesis can be derived by using the light- quantum posit as constituting evidence for that hypothesis unless one believed that the success of Planck's black-body equation inductively confirms a hypothesis analogous to (*): that all phenomena involving light are governed by equations derivable by treating light as particles.

By 1916, the novel predictions of Einstein's photoelectric equation had been verified, as had Einstein's predictions regarding the Volta effect. However, these results con- vinced virtually no one to accept the photon's reality. Whereas Einstein believed that the photon might be real if it turned out to be broadly useful, and therefore took the success of Planck's black-body equation to warrant advancing the photoelectric equation, Millikan [21, pp. 355f, 383, 388], [22, p. 230], for example, believed the photon unreal even if it turned out to be broadly useful. He championed its utility for the photoelectric effect by experimentally establishing the accuracy of Einstein's equation, while holding that the success of Planck's equation constituted no evidence at all for 'the bold, not to say the reckless hypothesis' of the photon and the photoelectric equation. Millikan's view was almost universal. Owen Richardson, for example, thought it coincidental that an empirically correct equation for the photoelectric effect followed from the light-quan- tum. He did not hold that the light-quantum hypothesis had been confirmed by any increment; rather, he concluded that Einstein's photoelectric equation 'evidently has a wider basis than the restricted and doubtful hypothesis used by Einstein' (quoted Stuewer [35, p. 259]). With the demise of semi-classical views after Bohr's 1914 atomic model, there were - as Millikan [22, p. 230] remarks - no notable alternatives to Einstein's theory that could yield his photoelectric equation. Nevertheless, most physi- cists didn't regard this equation's success as evidence for the light-quantum until after the Compton effect's discovery in 1922.

Whether one believes the photon real or believes merely that the light-quantum hypothesis is empirically adequate, one must believe in the truth of any empirical gener- alization derived from the light-quantum hypothesis and background beliefs. Belief in the posit's empirical adequacy is weaker than belief in its reality. Then why, between 1905 and 1922, did all those who believed in the empirical adequacy of the light-quan- tum hypothesis believe the photon real? Why did no one argue, from the empirical adequacy of Planck's black-body equation or Einstein's photoelectric equation, that though the photon is unreal, physicists should join Einstein in applying the light-quan- tum 'heuristic' widely?

The answer, I suggest, is that unless one believes that the photon may be real, and so that it may be a law rather than a coincidence that the light-quantum hypothesis is empir- ically adequate, one cannot regard its adequacy to one phenomenon as confirming, for each other conceivable phenomenon, its adequacy there. When can one regard an accepted empirical generalization, which follows from the light-quantum hypothesis, as confirming every other empirical hypothesis that derives from the light-quantum hypoth- esis, if one believes that H ( 'Any empirical hypothesis concerning phenomena involving light obtains if that hypothesis would obtain were the light-quantum hypothesis true') is non-lawlike? I answered this question in section IV: only when the photon's utility in connection with the given phenomenon inductively confirms a hypothetical 'common cause', i.e., a hypothesis L that one believes may be lawlike and (if L and H are physi-

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Marc Lange 633

cally necessary) might, for each empirical generalization deriving from the light-quan-

tum hypothesis, be partly responsible for its holding. Considering the diversity of the

phenomena to which the light-quantum hypothesis could be applied, it is unsurprising

that physicists possessed no plausible hypothesis L identifying a 'common cause' of their

all conforming to the light-quantum hypothesis, except for the light-quantum hypothesis

itself.

At the close of section III, I suggested why Einstein was rational in gambling on the

photon's reality, and so in regarding the fact that one phenomenon proceeds as if there is a light-quantum as confirming a hypothesis describing some other phenomenon as doing

likewise. By pursuing this strategy, Einstein takes a greater risk of making inaccurate

predictions in return for a chance at a greater reward: accurate predictions from the same

evidence of a broader range of phenomena. This is echoed in Planck's 1913 recommen-

dation that Einstein be admitted to the Prussian Academy. Planck incorrectly judged that

Einstein's gamble had failed, but he understood that a scientist is permitted to elect such

a risky inductive strategy:

That [Einstein] may sometimes have missed the target in his speculations, as, for

example, in his hypothesis of light-quanta, cannot really be held too much against

him, for it is not possible to introduce really new ideas even in the most exact sci-

ences without sometimes taking a risk. [13, p. 201]

VI. Natural Laws, Natural Kinds, and Connections of Natural Necessity

The foregoing presumed that belief in a posit's reality requires belief that it is no acci-

dent, but a natural law, that all phenomena in a particular range are as if that posit is real.

One might question this presupposition. Suppose I hypothesize that a mouse, going

unseen, has begun living in my apartment. On each of the next five mornings, I leave

cheese on the floor, and upon returning each evening, I find instead crumbs and tracks

shaped like mouse feet. I conclude that the posited mouse is real, and so that all recent

phenomena in my apartment are as if it is real. But it isn't a natural law that a mouse

lives in my apartment. Likewise, it is no natural law that all recent phenomena in my

apartment are as they would be if a mouse lived there.

Belief in a posit's reality doesn't always require belief that as a matter of law, all phenomena that, according to the theory, involve this posit are just as if it is real. Note

that none of the empirical correlations saved by the mouse theory (e.g., if cheese is left

on the floor of my apartment, it is soon replaced by crumbs and tracks shaped like mouse

feet) is physically necessary. Note also that the mouse is observable. In contrast, when

scientists believe a posited unobservable real, oftentimes they believe certain of the rele-

vant correlations physically necessary, as when scientists believed the photon real and

the photoelectric equation physically necessary. That is because in these cases, scientists

aren't positing particular unobservables of a familiar kind, such as an unobservabty tiny mouse living in my apartment. Rather, they are positing that the world includes a fur-

ther, unfamiliar kind of entity, e.g., the photon. Whereas the presence of a photon (or a

mouse) in a given spatiotemporal region is not physically necessary, it is a matter of nat-

ural law that the photon is a natural kind of elementary particle, a natural law that every

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634 Laws of Nature, Cosmic Coincidences and Scientific Realism

photon has zero rest mass, etc. Certain of the empirical correlations being saved by this

posit follow entirely from these and other laws. Thus, these correlations are physically

necessary, and so is the fact that they are just as if the photon is real.

It can be that there are photons, i.e., that photons exist, even if it is not the case that

the photon is real, i.e., is a natural kind of elementary particle - just as there are emeru-

bies (rocks that are either emeralds and exist before the year 2000 or rubies and exist

after 2000), and perhaps 'All emerubies are smaller than one cubic mile' is true, although

the emeruby is not a species of mineral. Whether we should say that a historical figure

refers to anything by (e.g.) 'caloric' , and so possibly makes a true claim about 'caloric',

depends (I believe, with Putnam [26]) on whether we believe that there are entities about

which enough of the claims that she (and certain others) made about 'caloric' (and that

we care about, in the present context) are true that she should (in this context), were she

told current scientific theories, identify these entities as what she was talking about.

Perhaps in one context, no 'caloric' exists, whereas in another, the 'caloric' held by a

body refers to the kinetic energy of its molecules.

Terrible muddles can result when questions such as 'Is chorea a real disease?' or 'Is

the emeruby a real mineral?' are confused with questions such as 'Are there any cases of

chorea?' or 'Are there any emerubies?'. Smart writes:

[A]s Grover Maxwell has pointed out, a man who disbelieved that molecules were

real things, but allowed that crystals (of sugar, say) were real things, would have to

face the difficulty that according to modern valence theory a crystal is in an important

sense a single huge molecule. [33, pp. 36ti]

But no contradiction can so easily be found in anti-realism applied to molecules.

Suppose someone denies, for example, that chorea is a real disease - say, because she

accepts the present view that there are several, entirely distinct diseases (Huntington's

chorea, Sydenham's chorea, St. Vitus' dance, Parkinson's disease, etc.) that all involve

the striking symptom (choreiform movements) definitive of chorea. She may admit that

there are some cases of chorea, namely, persons who involuntarily make choreiform

movements (rather than fake the symptom); she merely denies that chorea is the correct

diagnosis of these cases, that it constitutes a distinct illness. Similarly, one who denies

that molecules are real may admit that a given sugar crystal is real and qualifies as a mol-

ecule. But she holds that the things that qualify as molecules constitute no natural kind

(of the supposed sort), just as neither the emerubies nor the cases of chorea do.

When I discuss the hypothesis 'All phenomena involving light are just as if there are

photons', I mean by 'there are photons' that there exist some entities close enough to

qualify (in this context) as 'photons', not that the photon is a natural kind of elementary

particle. Obviously, if in fact there are photons (in this 'close enough to qualify' sense),

then 'All phenomena involving light are as if there are photons' is true - but it needn ' t be

a law. I have contended that for it to be a law that all phenomena involving light are just

as if there are photons, it must be because there are photons - not in the sense that there

exist some entities close enough to qualify, for that might be mere happenstance (and

thus be unable to supply the requisite physical necessity), but in the sense that the photon

is a natural kind of elementary particle, which is a matter of natural law. If the photon is

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Marc Lange 635

a natural kind of elementary particle, then it is no accident that, in connection with light,

there exist entities close enough to qualify as photons, and so it is no accident that all

phenomena involving light are as if there are photons.

Let me back up a bit in order to explain this more carefully. To begin with, what

does it mean to say that the photon is real, in the sense of being a natural kind of elemen-

tary particle? Intuitively, 'The photon is real ' (in this sense) concerns matters of

physical necessity. It means, I suggest, that there are laws of certain sorts: laws such as

'All photons h a v e . . , electric charge', 'All photons h a v e . . , rest mass', etc., where any

natural kind of elementary particle must have characteristic values of these quantities;

laws such as 'All photons carry energy', 'All photons carry momentum', etc.; and the

law that all phenomena involving light are as if there are photons. Natural kinds of (say)

disease must figure in laws of other kinds; that autism is a real kind of disease, not an

artificial category, perhaps requires that there be laws specifying autism's characteristic

symptoms, aetiology, responses (ceteris paribus) to various treatments, etc. Likewise,

perhaps a real kind of force must have a 'force law' (which specifies the strength and

direction of a component of this force under various conditions) along with laws con-

cerning the means (e.g., virtual exchange particle) by which the force acts, the energy

possessed by fields, and so on. For example, the Coriotis force has a force law but no

laws of the other kinds associated with real forces. That is because it manifests the force

accelerating the reference frame, which may be of any kind. Consequently, it is not one

of the real forces; it is termed a 'pseudoforce'.

This analysis of 'The photon is real [i.e., is a natural kind of elementary particle]'

accounts for the intuition (expressed two paragraphs ago) that this claim logically entails

'It is a law that all phenomena involving light are as if there are photons [i.e., as if there

exist entities close enough to qualify as photons]'. This analysis of 'The photon is real'

also bears out the intuition appearing in my initial argument regarding realism: for it to

be a law that all phenomena involving light are just as if there were photons, there must

be photons in the sense that the photon must be a natural kind of elementary particle.

Why is it that if the photon is not real in the natural-kind sense, then 'All phenomena

involving light are as if there were photons' doesn't state a natural law even if it is true

(as when there are entities close enough to qualify as photons)?

Because if the photon is not real in the natural-kind sense, then it is just a coincidence

(albeit perhaps a physically necessary one) that the laws covering light phenomena fit

together (perhaps along with certain initial conditions) so as to allow some things to exist

that are close enough to qualify as photons. To see this point, it may be best to set aside

the photon (since we do believe it to be a natural kind). Instead consider caloric - in a

context in which we take some extant things to be close enough to qualify as caloric

(e.g., the 'caloric' in a body refers to the kinetic energy of its constituent molecules) but,

of course, do not take caloric to be a natural kind of substance. The laws governing phe-

nomena involving heat (i.e., the laws of statistical mechanics, thermodynamics, thermal

conduction, etc.) include no laws of the form 'All caloric has the p rope r ty . . . '; if there

were such laws, it would be no coincidence that all phenomena involving heat are as if

there were caloric. Since 'caloric' figures in none of the laws governing thermal phe-

nomena, it is just a coincidence that these laws fit together so as to enable there to be

some things close enough to qualify as caloric, and so that all thermal phenomena are

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636 Laws of Nature, Cosmic Coincidences and Scientific Realism

just as if there were such things. 15 That laws not about caloric generate just the thermal

phenomena there would be if there were caloric is then a physically necessary coinci-

dence, jus t as a law about n i t rogen a toms and a law about a lkane hydrocarbons

coincidentally fit together so that all differences between the atomic weights of alkane

radicals are multiples of the atomic weight of any nitrogen atom. In sum: if it is a law

that all phenomena in a given range are as if there are P, that is because it is no coinci-

dence that the relevant laws allow there to exist entities close enough to qualify as P, and

that is because those laws are themselves about p.16

At the outset of this paper, I set aside the question of what makes some regularity a

law. But it is in connection with this issue that the relation just proposed between laws

and natural kinds may comfort those empiricists (e.g., van Fraassen) who see the same

arguments (e.g., doubts about inference to the best explanation) as leading both to anti-

realism and to the view that ' in nature there is no extra element of necessary connexion'

(Braithwaite [2, p. 294]) in virtue of which certain regularities are laws. Just as (I have

suggested) the photon is a natural kind because there are laws of certain types governing

all photons, so this 'e lement of necessary connexion' is a real kind of thing in nature

only if there are laws of certain types governing all laws. As to the sorts of laws by

which laws must be governed in order for them to constitute a natural kind, this would be

for science to reveal, just as science has rejected the hypothesis 'It is a law that for each

element, there is a law specifying its atomic weight ' and has discovered the law that for

each element, there is a law specifying the number of protons in all atoms of that kind.

But scientists haven ' t searched for laws governing lawhood, nor have they tried to

discover the sorts of laws by which lawhood must be governed for it to be real. As Kim

[12, p. 232] asks rhetorically, 'Which of the special sciences are responsible for investi-

gating the properties of the causal relation itself?'. Scientists don ' t work to explain why

(e.g.) no known law refers to July 22, 1995 by trying to uncover some law governing

lawhood (e.g., 'It is a law that no law refers to any particular moment ' ) . If they offer any

explanation at all, it consists of some more fundamental, unified set of laws that explains

those laws that were already known. There is another reason it seems to me counter-intuitive and contrary to scientific

practice to allow for laws governing lawhood. If it is a law that all laws have property Y

(for some property Y whose possession by a given regularity is a matter of logical neces-

sity), then the lawlikeness of certain claims is physically impossible. But while a

generalization's truth might be physically impossible, it seems to me counter-intuitive

for a generalization's lawlikeness to be physically impossible. In other words, I see no

evidence that in scientific practice, a distinction is drawn between those accidental gen-

eralizations that just happen (i.e., as a matter of physically unnecessary fact) to be

15 This subjunctive conditional - concerning how phenomena would be if there were things close enough to qualify as caloric - is context dependent, just as how some thing must be in order to qualify as caloric is context dependent. Indeed, these two dependences are connected, since how phenomena would be if there existed caloric depends on how some thing must be in order to qualify as caloric.

1~ The subject of fn. 13 provides another example. According to some ancient astronomers, the planets' natures do not demand that the planets move along epicyclic and deferential compo- nents, and so there aren't real epicyclic and deferential component planetary motions. It is therefore a (physically necessary) coincidence that the resultant motions can be decomposed into epicyclic and deferential components.

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Marc Lange 637

non-lawlike and those accidental generalizations whose non-lawlikeness is physically

necessary. On this view, empiricists are correct in holding that when scientists believe 'All Fs

are G' to express a law, they aren't positing an unobservable 'element of necessary con-

nexion'. The 'compulsion' in nature that makes one thing happen because another does

cannot be cashed out as the reality of some novel kind of posit because the reality of a

novel kind of posit is itself cashed out in terms of the natural laws.

Faraday and Maxwell saw themselves as trying to discover what it would take for the

expression 'electric line of force' to be more than a formal device for expressing the

'potential' force at various locations - what it would be for this expression to refer to

entities that constitute a genuine kind of line of force. Just as scientists have ascertained

that as a matter of natural law, for any species of elementary particle, F, there is a law

'All Fs h a v e . . , rest mass', so Faraday and Maxwell aimed to identify kinds of proper-

ties such that for each kind, it is a natural law that all lines of force of a given species

(electric, gravitational, magnetic, etc.) share some property of this kind. To suppose that

the sense in which a line of force is real is not a matter for science to discover, but is

identical to what it is for familiar macroscopic objects to be real, cannot account for why

Faraday and Maxwell investigaied whether the electric line of force is real even after rec-

ognizing that 2n lines of'force are posited as leaving a unit charge. Science not only

discovers what diseases, elementary particles, and minerals there are; it also discovers

what it is (or would be) for chorea to be a real disease, the photon to be a real elementary

particle, and the emeruby to be a real mineral.

University of California, Los Angeles Received March 1995

Revised October 1995

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638 Laws of Nature, Cosmic Coincidences and Scientific Realism

REFERENCES

1. R.B. Braithwaite, 'The Idea of Necessary Connexion (I)', Mind 36 (1927) pp. 467-477. 2. R.B. Braithwaite, Scientific Explanation (Cambridge: Cambridge University Press, 1955). 3. A. D'Abro, The Rise of the New Physics, Vol. H (New York: Dover, 1951). 4. F. Dretske, 'Laws of Nature', Philosophy of Science 44 (1977) pp. 248-268. 5. A. Einstein, 'Uber einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristis-

chen Gesichtspunkt', Annalen der Physik 17 (1905) pp. 132-148. 6. A. Einstein, 'Zur Theorie der Lichterzeugung und Lichtabsorption', Annalen der Physik 20

(1906) pp. 199-206. 7. A. Einstein, 'Plancksche Theorie der Strahlung und die Theorie der spezifischen Warme',

Annalen der Physik 22 (1907) pp. 180-190, 800. 8. J. Foster, 'Induction, Explanation and Natural Necessity', Proceedings of the Aristotelian

Society 83 (1982-3) pp. 87-102. 9. N. Goodman, Fact, Fiction, and Forecast, 4th edn. (Cambridge, MA: Harvard University Press,

1983). 10. I. Hacking, 'Do We See through a Microscope?' in P. Churchland and C. Hooker (eds.), Images

of Science (Chicago: University of Chicago Press, 1985) pp. 132-152. i1. C.G. Hempel, Aspects of Scientific Explanation and Other Essays. . . (New York: Macmillan,

1965). 12. J. Kim, 'Realism and Explanatory Exclusion' in P. French et al. (eds.), Midwest Studies in

Philosophy, Vol. XII (Minneapolis: University of Minnesota Press, 1988) pp. 225-239. 13. G. Kirsten and H.-G. Korber (eds.), Physiker uber Physiker (Berlin: Akademie-Verlag, 1975). 14. W. Kneale, Probability andlnduction (Oxford: Clarendon Press, 1952). 15. M. Lange, 'Lawlikeness', Nous 27 (1993) pp. 1-21. 16. M. Lange, 'Scientific Realism and Components: The Case of Classical Astronomy', The Monist

77 (1994) pp. 111-127. 17. M. Lange, 'Earman on the Projectibility of Grue' in D. Hull, M. Forbes, and R.M. Burian (eds.),

PSA 1994, Volume I (East Lansing: Philosophy of Science Association, 1994) pp. 87-95. 18. M. Lange, 'Are There Natural Laws Concerning Particular Biological Species', The Journal of

Philosophy 92 (1995) pp. 430-451. 19. M. Lange, 'Inductive Confirmation, Counterfactual Conditionals, and Laws of Nature',

Philosophical Studies, forthcoming. 20. J.L. Mackie, 'Counterfactuals and Causal Laws' in R.S. Butler (ed.), Analytic Philosophy (New

York: Barnes and Noble, 1962) pp. 66-80. 21. R.A. Millikan, 'A Direct Photoelectric Determination of Planck's "h"', Physical Review 7

(1915) pp. 355-388. 22. R.A. Millikan, The Electron (Chicago: University of Chicago Press, 1917). 23. G.E. Moore, Common-Place Book 1919-1953 (London: George Allen and Unwin, 1962). 24. A. Pais, Subtle is the Lord (Oxford: Oxford University Press, 1982). 25. C.S. Peirce, Collected Papers, Vol. 5 (Cambridge, MA: Harvard University Press, 1934). 26. H. Putnam, Meaning and the Moral Sciences (London: Routledge, 1978). 27. H. Reichenbach, Experience and Prediction (Chicago: University of Chicago Press, 1938). 28. H. Reichenbach, Elements of Symbolic Logic (New York: Macmillan, 1947). 29. W. Salmon, 'Empiricism: The Key Question' in N. Rescher (ed.), The Heritage of Logical

Positivism (Washington: University Press of America, 1985) pp. 1-21. 30. W. Salmon, 'Four Decades of Scientific Explanation' in W. Salmon and P. Kitcher (eds.),

Minnesota Studies in the Philosophy of Science, Vol. XIII (Minneapolis: University of Minnesota Press, 1989) pp. 3-217.

31. W. Salmon, 'Reichenbach on Realism' in W. Salmon and G. Wol'ters (eds.), Logic, Language, and the Structure of Scientific Theories (Pittsburgh: University of Pittsburgh Press, 1994) pp. 139-46.

32. W. Salmon, 'Carnap, Hempel, and Reichenbach on Scientific Realism' in [31, pp. 237-254]. 33. J.J.C. Smart, Philosophy and Scientific Realism (London: Routledge, 1963). 34. P.F. Strawson, Introduction toLogical Theory (London: Methuen, 1952). 35. R.H. Stuewer, 'Non-Einsteinian Interpretations of the Photoelectric Effect' in R.H. Stuewer

(ed.), Minnesota Studies in the Philosophy of Science, Vol. V (Minneapolis: University of Minnesota Press, 1970) pp. 246-263.

36. B. van Fraassen, The Scientific Image (Oxford: Clarendon Press, 1980). 37. B. van Fraassen, Laws and Symmetry (Oxford: Clarendon Press, 1989). 38. J.W. van Spronsen, The Periodic System of ChemicaIElements (Amsterdam: Elsevier, 1969).

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