shapere (sobre) toby linden - shapere on observation

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Shapere on ObservationAuthor(s): Toby Linden

Source: Philosophy of Science, Vol. 59, No. 2 (Jun., 1992), pp. 293-299Published by: The University of Chicago Press on behalf of the Philosophy of Science Association

Stable URL: http://www.jstor.org/stable/188249 .

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DISCUSSION:

SHAPERE ON OBSERVATION*

TOBY LINDENtt

Department of PhilosophyUniversity of Maryland at College Park

In his article "The Concept of Observationin Science and Philosophy"(1982),

Dudley Shapere argues for an analysis of what it is for an object to be directlyobserved (observable). He does so by presenting two contrasting ways of ob-

serving the center of the sun. However, his examples, which are probabilisticin nature, are at odds with his analysis, which is absolute. I argue that of thethree features of the examples which could serve as the basis for the analysis

only one-the amount of alteration to the information being transmitted-canplausibly do so. Having reworkedShapere's analysis on the basis of this feature,I show that the analysis still fails to provide a sufficient condition for obser-vation.

In "The Concept of Observation in Science and Philosophy" (1982)

Dudley Shapere cites several examples of eminent astrophysicists claim-

ing that they are able to directly observe the center of the sun. They saythis despite the fact that the center of the sun lies buried beneath 400,000miles of opaque material which is at such high temperaturesandpressures

that it seems as if the region must be forever beyond our ability to gain"direct access to it, especially 'observational'" (1985, 24). However,

Shapere claims that these scientists are highly sensitive to the conceptsand techniques of their subject and so their claims that they are able to

make direct observations should be taken seriously (1982, 487).

Shapere suggests that the way to understand the concept of direct ob-

servation as it is used in science is by examining the contrast between

two different ways of obtaining information about the center of the sun:

through the collection of electromagnetic radiation in the form of light

photons originating at the center of the sun, and by the reception of neu-trinos from the solar core. Shapere says that information gathered by the

first method must be regarded as "indirect"or "inferential". This is be-

cause the mean free path of a photon is very small. Hence, a packet of

*Received October 1988; revised November 1990.

tI would like to express my gratitudeto Frederick Suppe for his help. I also benefitedfrom the comments of two referees.

tSend reprint requests to the author, Department of Philosophy, 4360 Computer and

Space Science Building, University of Marylandat College Park, College Park, MD 20742-

7615, USA.

Philosophyof Science,59 (1992)pp. 293-299

Copyright ? 1992 by the Philosophy of Science Association.

293







TOBY LINDEN

photons released at the center is absorbed, reradiated, or scattered in its

passage to the surface of the sun and, consequently, "the original char-

acter of the radiation . . . [is] altered drastically in the process" (ibid.,

491). In constrast, Shapere says, there is only a "low probabilityof [neu-trinos] being interfered with in their passage. . . . Any information they

carryis thus unalteredby interactionsalong the way"(ibid.). Hence, neu-

trinos provide us with direct observation of the center of the sun.

Shapere therefore proposes the following analysis:

x is directly observed (observable) if:

(1) information is received (can be received) by an appropriate re-

ceptor; and

(2) that information is (can be) transmitteddirectly, i.e., without in-

terference, to the receptor from the entity x (which is the source ofthe information). (Ibid., 492)

This description of the two examples and the presentationof the analysis

appears in at least one other place in Shapere's work (1985, 24).

However, this analysis does not follow from the examples as they are

presented. As Shapere describes them, the only contrast between the two

examples is that the neutrinos have only a low probability of being in-

terfered with, while the photons are highly likely to undergo interference

(since the mean free path is very small). And yet, the analysis, as Shapere

presents it, contains an absolute condition: No interference is possible if

direct observation is to take place.Moreover, there is another objection to using the level of probability

as the key element in the analysis and that is that it would seem to giveus, at best, only an account of what it is for something to be observable.

On Shapere's own account for something to be observed means that on

this occasion the radiation (or the information carried by the radiation)was not interferedwith (or was not altered or lost). The likelihood of the

interference alteration) s not relevant to whetheran observationhas taken

place on a particularoccasion.

Shapere might argue that if one looks at the examples more closely, it

can be seen that the probability of interference does give an account of

what it is for an object to be observed. For if interference is rare then it

can be assumed on any given occasion that interference has not taken

placeand hence that a direct observation has been made. This, however,

does not seem to fit the facts of the neutrino case. As Shapere describes

that case, the theories of the source and transmissionpredict the expectednumber of neutrinos that areto be captured. The experiment is run several

times and several readings are obtained. If a significant number of neu-

trinos (as determinedby the theories) are collected then the center of the

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SHAPERE ON OBSERVATION

sun can be said to have been directly observed. Since a determinationof

whether a direct observation has taken place is not made until several

readings have been taken, it is hard for Shapere to claim that the lack ofinterference on a given occasion is crucial in permitting the conclusion

that a direct observation has taken place to be drawn. Perhaps Shaperewould claim that the consistency of the results of each run (if indeed this

was the case) would indicate that no interference takes place. However,this refined version of Shapere's analysis would still be fundamentally

probabilistic and hence would still conflict with the absolute criterion in

the second clause of the analysis.A more satisfactory analysis is required. I will provide one by follow-

ing Shapere's suggestion that the photon and neutrino examples providethe "key to understanding"(1982, 490) the use of the scientific termi-

nology. There are three features of the two examples Shapere introduces

which could serve as the basis of a contrast, and hence as the basis of

what it is for something to be directly observed or observable: the prob-

ability of interference;the amount of interference with the radiation;and

the amountof alteration to the informationcarriedby the radiation. I have

shown that Shapere introduces the probability of interference. He also

says that in the photon case the character of the radiation is altered while

in the neutrino case the information is said to be unaltered. In fact his

analysis obscures the difference between the characterof the information-

bearing object and the informationcarriedby that object, for he says that

the information is transmitted "directly, i.e., without interference". Ob-

jects are interfered with, but information is transmitted. I have shown

that the probabilityof interference cannot do the work that Shapere wants

his analysis of observation to perform. I will show that this is true of the

second feature as well. I will then argue that the third of these features,the amount of alteration to the information, is the crucial feature and

suggest a rewording of Shapere's analysis.The second feature, the amount of interferencewith the radiation, does

not look as if it can be crucial to Shapere's account. This is because,

first, he has claimed that in the photon case there is so much interference

that the original character of the radiation has been altered drastically,but he does not, as was noted before, explicitly contrast this by claimingthat in the neutrino case little or no interferencehas taken place. Second,his analysis only mentions the transmission of information and does not

mention the character of the radiation. Third, and most importantly, it is

significant that the analysis only refers to the interferencethat takes placebetween the source and the receptor. Shapere must also provide an ac-

count of what happensto the radiationafter it reaches the receptor. There

is, of course, an intuitive difference between interference that occurs be-

fore the radiation reaches the receptor and that which occurs after it. Put

295







TOBY LINDEN

roughly, the changes that occur in the receptor are (in some sense that

needs to be specified) controlled. Shapere says that a theory of the re-

ceptor or measuring device is needed and this is part of what he calls the

"background nformation"(ibid., 513). Indeed without such a theory, and

theories of the source and transmission,the experiment"would have been,in the most literal sense, inconceivable" (ibid.). What is importantwith

changes that occur in the receptor (and surely also between the source

and the receptor) is not that interference occurs, but that information is

not altered or lost. Some interference with the radiation results in infor-

mation being lost, but some does not. If the interferencecan be accounted

for (as it is in the receptor) then it does not prevent direct observation.

After all, Shapere himself says that the neutrinosdo interact in their pas-

sage but the information that they carryis not lost or altered (ibid., 491).So I argue that it is the third feature of the examples, the amount of

alterationto the information, that is crucial in Shapere's account of direct

observation. Further evidence that this is the case is provided by the fol-

lowing passage:

... the contrastof observational status between neutrino and photon

reception requires . . . information about factors contributing to the

opacity of the sun to the passage of photons there (i.e., interferencewith the photons). Those factors are specified in modem physics ....

[T]he difficulties of estimatingeach-that is definite and specific waysin which our knowledge of those interferences falls short-are also

laid out by currentphysics. (1985, 24)

This quotation seems to imply that if we had the relevant knowledge, if

our knowledge did not fall short, then we would be able to directly ob-

serve the center of the sun by means of photons. This would seem to be

the case even though the photons do interact with other things in theirpassage.

This focus on the information transmitted ratherthan the character of

the radiation fits well with an account of observation in science since

science essentially involves human beings. If there were no human ele-

ment in observation then anythingthatwas able to collect neutrinoswould

be able to make observations. Patches of grass would fall in this category.That is, observations are essentially observations by us. It is our science

that tells us that patches of grass are not receptors. As Shapere says,"whatever informationis received throughthe 'appropriatereceptor' mustbe transformed . . . into humanly-accessible form" (1982, 508). How-

ever, he goes on to say that a human perceiver need not be there "for

years. Yet it still counts as observational" (ibid., 509). Thus far away

galaxies are detected and observed by exposing light-sensitive plates over

296








a long period of time. Still, if no human eventually entered into the pro-cess, it would be hard to maintain that the process was observational.

In anotherpartof his article, Shapere (1982) suggests that the neutrinoand photon cases also differ with respect to the reliability of the back-

ground beliefs (which are those supplied by the theories of the source,

transmission, and receptor) in each case. Shapere links the reliability of

background beliefs to whether conclusions about the source are said to

be inferentially or noninferentially based. Shapere says that the conclu-

sions based on uncertainties are "inferential". Conclusions from both the

photons and neutrinosare inferentially based in one sense since they both

require backgroundknowledge that serves as "premises" and makes the

observations, calculations and conclusions possible (ibid., 517). How-ever, there is a sense in which the two cases do differ:

[In] the epistemically importantsense-the sense which is central in

the quest of knowledge-inference is spoken of ratherin connection

with reasoning and conclusions that we have specific reason to be-

lieve are doubtful; where the beliefs upon which we build are not

subject to specific doubt . . . the reasoning is not spoken of as "in-

ferential". (Ibid., 517).

Presumably, these beliefs could be doubtful in at least two ways: On the

one hand, there could be some doubt as to whether the theories are ac-

curate; on the other hand, it may be that the theories do not completelydescribe the situation. In the lattercase, the problem is lack of knowledgeratherthan the doubtful status of knowledge already possessed. Shapere

suggests that the neutrinos allow us to observe the center of the sun be-

cause the informationprocess they are part of is reliable. The low prob-

ability in this case means that there are no reasons for specific doubt about

the background beliefs. In contrast, the high probability in the photoncase means there are specific reasons for being cautious about the con-

clusions drawn on the basis of informationthe photons provide. The waysin which the informationprovided by the photons is altered in their pas-

sage "cannot be taken into account specifically and precisely" (Shapere,n.d. 14). Again, Shapere seems to be saying, given more and better in-

formation, given beliefs which are not subject to doubt, it would be pos-sible to observe the center of the sun using photons. Similarly, in the

photon case he says:

[Photons], however, once released at the surface, can be expected to

travel without further serious interference to our receptors of electro-

magnetic energy. Hence we speak of observing the surface of the sun

by means of those receptors (including eyes), but of the necessity(because of the uncertainties involved) of inferring, on the basis of

297







TOBY LINDEN

such observation, what goes on in the solar interior. (1985, 24; em-

phasis in original)

In this last passage, Shapere suggests that the importantcontrast is be-

tween observation of the surface of the sun and inference about the center

of the sun. Given the previous discussion it would be natural to take

Shapere to be claiming that inferential conclusions are not observations

(or perhaps are not based on observations-there may be an ambiguity

here). So the phrase "such observation" refers to observations of the sur-

face of the sun. For this is to be true, the distinction between inferential

and noninferentialwould need to be equivalent to the distinction between

nonobservation and observation. This can only be so, however, if thequalifier "direct" does no work and if Shapere is taken to be trying to

derive an analysis of "observed (observable)" instead of "directly ob-

served (observable)". Fortunately, there are reasons for believing this to

be so. First, the title of Shapere's paper does not use the qualifier "di-

rect". Second, Shapere frequently uses "directlyobserve" and "observe"

interchangeably. For example, he says that "we speak of observing the

surface of the sun by means [of electromagnetic energy]" (ibid.) but also

that "it is possible to observe directly the surface of the sun through pho-

ton receptors .. ." (1982, 500). And third, the one time he addresses theissue face on, he implies that direct observation is noninferential:

Although claims about the center of the sun based on photons, like

those based on neutrinos, are "based on observation", the sense in

which they are so based is not that of being "directly", but only

"inferentially"so based. But since the operative contrast here is be-

tween "observational"and "inferential", the term 'direct' in 'direct

observation' has the function only of emphasizing that conclusions

about the source are being arrived at by observation, and not by in-

terference based on observation. (That is, the idea of "indirect ob-

servation" plays no role at all.) (Ibid., 512)

Though this passage is difficult, he does seem to be saying (particularlyin the last sentence) that there is no such thing as indirect observation.

Thus I have argued that the relevant contrast between the neutrino and

photon cases is the amount of unaccounted for or unreliable interference

which the information is subject to in its transmission from the source to

the receptor. I have shown how this emphasis on the information being

transmitted(ratherthan the character of the information bearer) cohereswith the epistemic role that Shapere wants his account of observation to

perform. So I propose the following rewording of Shapere's analysis:

x is observed (observable) if:

(1) information is received (can be received) by an appropriatere-

298








ceptor, from an entity x (which is the source of the information);and

(2) that information is (can be) transmittedreliably, i.e., there are

no specific reasons for doubting that any interference to the radiationis accounted (accountable) for.

(I have moved the phrase "from an entity x" to the first clause, whereas

Shapere placed it in the second. I take this to be a stylistic and not a

substantive change.)

Finally, I would like to mention a peculiar feature of the neutrino ex-

perimentwhich casts doubt on the general applicability of Shapere's anal-

ysis, despite his claim that the neutrinoexperiment contains characteristic

features of scientific observation and that "the relations between receptorand source in this case are paralleled in such cases as telescopic, spec-

troscopic, andphotographic eceptionof photons .. ." (ibid., 513). Shapere

says that the neutrinos do not carry the information about where theycame from and this is true of observations made with other instruments.

What this means in the typical scientific set up is that the receptor is

pointed in the direction of the source to be observed. However, this is

not true of the neutrino experiment. Shapere says that it is possible to

conclude that the neutrinos captured in the receptor came from the sun

because that is the only place they could have come from and the energylevel of neutrinos from other sources is (normally) below the threshold

of the apparatus(ibid., 513, f.n. 14). But notice that it is the theory of

the source and transmission, not the directionality of the receptor that

permits us to say that we have made an observation. Shapere is explicitthat he intends his analysis only to provide sufficient and not both nec-

essary and sufficient conditions for observation (ibid., 510, f.n. 13).

However, the considerations above show that without some account of

focusing, his analysis will fail even to be sufficient.

REFERENCES

Shapere, D. (1982), "The Concept of Observation in Science and Philosophy", Philosophyof Science 49: 485-525.

. (1985), "Observation and the Scientific Enterprise", in P. Achinstein and 0.

Hannaway (eds.), Observation, Experimentand Hypothesis in Modern Physical Sci-ence. Cambridge, MA: MIT Press, pp. 210-245.

. (n.d.), "Rationalism and Empiricism: A New Perspective". Unpublished manu-

script.

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