laws and other worldsby fred wilson

Canadian Journal of Philosophy

Laws and Other Worlds by Fred WilsonReview by: George N. SchlesingerCanadian Journal of Philosophy, Vol. 19, No. 1 (Mar., 1989), pp. 155-160Published by: Canadian Journal of PhilosophyStable URL: http://www.jstor.org/stable/40231641 .

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CANADIAN JOURNAL OF PHILOSOPHY 155 Volume 19, Number 1, March 1989, pp. 155-160

Critical Notice

FRED WILSON, Laws and Other Worlds. Dordrecht: D. Reidel 1986. Pp. xiv + 328.

I

This book deals with a variety of fundamental issues in the philosophy of science. Among others, it touches upon problems involving the laws of nature, causality, determinism, explanations, predictions and counterf actuals. The arguments (some of which might have been shortened rather than carried on, without a break, for too many pages) are formulated with considerable care and the relevant presuppositions are explicitly stated. Professor Wilson is not bent on startling the reader with spectacular novelties; he strives to avoid fanciful theses and painstak- ingly seeks to remain as close as possible to what he takes to be a tradi- tional empiricist (Humean) position.

The book is divided into three chapters. The title of the first chapter is 'Science and Scientific Explanation,' in which Wilson defends Hem- pel's D-N theory of explanation. Though this simple theory cannot stand as originally formulated, essentially it faitfully reflects explanations produced by practical scientists. Wilson goes as far as to defend a moot corollary of Hempel's account, the symmetry thesis that the set of sentences which provides an adequate explanation after the event, can always serve, prior to the event's occurrence, as means for predicting it, and vice versa. One well known example cited by the opponents of the thesis involves the predictability of the height of a flagpole on the basis of information about the length of its shadow and the sun's position, through the use of elementary geometrical optics. It has been claimed that, contrary to the symmetry thesis, the same information is not suited to form an appropriate explanation why the flagpole is as high as it is.

Wilson sees no merit in this objection. He is prepared to concede that the length of the shadow cannot form a part of an explanation why the flagpole has a certain height, but insists on its legitimate role



156 George N. Schlesinger

in an explanation supplying a reason why the pole must be of such and such height (18). Now if we reject the idea that Wilson might have intended to claim that some ascriptions of physical features to the flagpole may necessarily, and not merely contingently, be true, then we are left wondering what precisely did he mean by the phrase 'must be? The answer seems that all he wished to convey is that once we have measured the shadow and the sun's elevation we definitely know what the height must be. But then at most we have an explanation how we know, and not why it is, that the flagpole has a certain height. Thus symmetry does not obtain, for what we are able to explain is not what we are able to predict.

Indeed, after a brief reflection on the basically dissimilar objectives predictions and explanations serve in general, one is likely to expect that the set of sentences that may be employed in the context of one, need not qualify for use in the context of the other. It seems natural that an enlightening explanation be somewhat harder to come by than a prediction; that the former has a more elaborate structure, has a large number of conditions to satisfy, than the latter. Prediction has solely a practical purpose, we should be pleased with anything that helps us to foresee future events, regardless of whether it increases our understanding of the factors producing them. Explanations, on the other hand, are supposed to reveal the interconnectedness of phenomena and increase our understanding of what has happened through telling us why it has happened. Furthermore, in the case of a prediction there are only two possibilities: it is either successful or it is not. Ex- planations, on the other hand are not merely correct or incorrect; correct explanations themselves may differ from one another in a variety of ways: some are more detailed, more far-reaching, more convincing and more illuminating than others.

Thus, for example, in order to serve as scientific explanans, a set of sentences must include an empirical generalization, so as to show what law demanded the occurrence described in the explanadum, i.e. to show that it was required by the very nature of the universe. In the case of predictions, as long as we can get hold of a set sentences which will work, we place no restrictions on it. Suppose, for example, I know that the lecture hall seats 1500 people and observe that all but 10 seats are occupied and no one is standing, then I can correctly predict that the number of people in the audience will turn out to be 1490. Obvi- ously, the same set of sentences cannot serve to explain why that many people came to the lecture; indeed it is in principle disqualified from explaining anything whatever, since it fails to include an empirical generalization. That failure is however entirely irrelevant to its effec- tiveness as a tool for prediction.



Critical Notice of Fred Wilson Laws and Other Worlds 157

II

In Chapter Two, Wilson devotes copious discussion to the long- standing problem how to describe the difference between true statements that amount to laws of nature and others that are no more than accidental generalizations. He astutely exposes some of the flaws in the solutions offered in the past. He criticizes the well known attempt to characterize laws as being capable - unlike accidental generalizations that are incapable - of sustaining their counterf actuals. Wilson maintains that the notion of 'counterfactuals' is not available for use in the definition of 'laws of nature/ since the latter is logically more basic and is indispensible for the definition of the former (88).

He also examines the suggestion of Armstrong and Tooley that the laws of nature refer to necessary connections between the universals they mention. Wilson spends a great amount of time trying to recon- struct their thesis so as to lend it some substance as well as plausibili- ty. Throughout the entire discussion he displays remarkable fairness to an approach he clearly does not find congenial.

Wilson's own view on the matter, which he attributes to Hume is, that the very question 'What is the difference between a law and an accidental generality' is misleading. To pose such a question 'suggests we must look for some special virtue of laws, over and above their matter-of- fact universality that distinguishes them from other matter-of-fact generalizations called accidental generalities. But if the Humean is correct, there is no such special virtue, and to seek it is unreasonable' (96). How- ever, he does not oppose attempts to draw a subjective distinction.

One may be prompted to inquire: surely Wilson concedes that a variety of possible descriptions of the world are conceivable in each of which different initial conditions may obtain under identical sets of laws. If in some of these instances certain generalities are true, while in others they are false, then these generalizations could by definition not amount to laws of nature. But they cannot be accidental generalizations either, for we are told they cannot be distinguished from laws. What then are they according to Wilson?

At one stage in his discussion Wilson expresses the view that accidental generalizations have one crucial feature that distinguishes them from laws, namely, that we are very uncertain about their credibility. He considers the example of a generality that Chisholm has claimed to have established concerning a certain park bench (B) on the Boston Common, namely that only Irishmen sit on B. Wilson points out that Chisholm's generalization may be true only because no non-Irishman decided to sit on B. But humans are known to be fickle and their in- tentions and decisions are inconstant. Thus at any time in the future the generalization may become falsified. Wilson therefore concludes:




Accidental generalizations are evidentially weak not because their instances do not testify to their truth but because background knowledge testifies to the un- likelihood of the generalities continuing to hold in the total population. (104)

First we may note that if this is indeed so then Wilson has after all come up with a difference between two types of generalizations that is objective enough to satisfy even the hardest to please. More impor- tantly, in many cases it is obviously the opposite of what Wilson says is true. Let us assume that B was manufactured only ten days ago and it has been under constant surveillance until now and it has been observed that no one except Irishmen came anywhere near B. Now the bench is burnt and thus it is ensured that no one in the future is going to sit on B. In this case it is evident that we would have a greater meas- ure of certainty concerning the generalization about B than is ever possible to have about law-claims that remain subject to falsification.

This example could be taken as providing a clue to the source of an important difference between the two kinds of statements under in- vestigation, namely, the methods available for their confirmation. Un- like the credibility of accidental generalizations, the credibility of a lawlike generalization cannot be established by a complete enumera- tion of their instances. Laws of nature are discovered by reasoning that goes beyond the evidence, by the use of the scientific method of ex- trapolation. They refer to unobserved instances, as well as the observed ones on which they are based. An accidental generalization like the one about bench B, on the other hand, is practically nothing more than a summary of what we have observed.

Ill

The final chapter is mainly devoted to a discussion of counterf actuals. Wilson rejects the newfashioned approaches based on the assumption that only through considering what goes on in various possible worlds does one arrive at a correct understanding what such expressions mean and what their truth-conditions are. Instead he defends a certain ver- sion of the received view according to which a counterf actual is a 'col- lapsed argument' (232) which may be asserted just in case its antecedent conjoined with a variety of implicit statements of facts (or the explicit part of the antecedent plus its unstated parts), coupled with certain law-assertions, logically imply the consequent. To these conditions he adds the important qualification that what may be taken to be includ- ed among the implicit premises varies from instance to instance and depends on the cognitive interests and the circumstances in which the expression is used.



Critical Notice of Fred Wilson Laws and Other Worlds 159

In the course of the extensive discussion that follows, Wilson does not seem to make full use of the insight he repeats several times, concerning the context dependence of the meaning of conditionals. On p. 249, for instance, he embarks upon a protracted examination of the famous problem invented by Nelson Goodman, namely, why it is that the counterf actual 'If match m had been scratched it would have lighted' is accepted while 'If m had been scratched it would not have been dry' is not? It is hard to see why Wilson did not follow his own line and produce a relatively very short reply. He could have simply de- nied that Goodman had raised any question that requires an answer, since it is simply false that the first expression is and the other is not acceptable. It all depends on the context. In a bare context, where we are not told who is uttering, under what circumstances and in refer- ence to which particular match, either of these sentences, the first coun- terfactual is the one that seems to be addressed to our cognitive interests. What may be said to be a significant feature of matches in general, a feature that sets them apart from all animals, vegetables and minerals, is that under normal conditions they light when scratched. And of course, there are indefinitely many explicitly describable con- texts in which 'If m .... it would have lighted' is the admissible expression, as when uttered in the midst of an argument about the dependability of the manufacturers of m and the quality of the matches they produce.

Let us imagine, however, the following situation. Alf's apartment, which is near a chemical factory where an accident occurred this morn- ing, is now filled with inflammable vapors. Before leaving for work, Alf explained to the members of his household that the smallest flame could set their whole building on fire and warned everybody to do nothing that may cause such a catastrophe. Later tonight Ben visits the stricken family and hears Alf pointing at a well made, dry match, declaring 'If this match had been scratched today it would not have been dry.' Subsequently Alf's wife confides to Ben that their two children, neither of them five years old yet, habitually play with matches, yet today they were very mindful of their father's monition and would not have struck any but wet matches, so as to avoid an explosion.

Under these circumstances Ben could not fail to understand, that what Alf was trying to convey through his utterance was something significant about their children, and that his implicit premises includ- ed the statement that the match that is struck does not light. Some of the other expression pairs discussed in the book could have also been treated similarly: under certain circumstances it may be clear to all concerned that the specific statement the speaker intends to make, requires the uttering of the expression A > B, while under other circumstances the context may indicate that he wishes to assert something




else that can properly done only by voicing of A > C, where B and C may be contraries.

On p. 240 Wilson says '... the antecedent, both its explicit and implicit parts, must be logically and lawfully realizable, that is, it must be logically self-consistent with (known) laws of nature/ It is not entirely clear why he should insist on all these restrictions. For example, I may be with a friend in the room, who remarks 'If Tennyson had been right when he wrote "walls have ears" I would not be telling you this now/ I would realilze that he is anxious that I should keep the information he is imparting to me a secret. In this case, the explicit part of the antecedent my friend has uttered, imputing hearing organs to the inanimate walls is certainly contrary to the known laws of nature. So also seem some of the implicit parts which include the statement that the walls are familiar with the language we are speaking, have memory and are capable of reporting our conversation to other people. These kind of counterfactuals are not uncommon and a full exposition ought to account for them as well.

IV

Probably the most interesting aspect of the book is the basic idea un- derlying most of the major arguments, namely, that empiricism is not just a metaphysical doctrine concerning the ultimate source of human knowledge. Wilson believes it to be a comprehensive principle which is to be our guide in adopting the suitable position with respect to the nature of explanations, laws, counterfactuals, and indeed with respect to every substantial topic in the philosophy of science.

It is, of course, a debatable idea. For example, on the first page of the Preface, Wilson declares The essay is written in the conviction that there are no... worlds other than the actual.' One may be inclined to agree that the rule not to go beyond the evidence requires us deny the reality of worlds other than the actual. But surely an empiricist's conscience should not in the least debar him from making use of the concept of 'possible worlds' as a tool of analysis. In particular, while one may have any number of reasons for adopting Wilson's account, the fact that apart from the actual world none have any substance, provides no reason for rejecting the possible world analysis of counterfactuals.

Received January, 1988 GEORGE N. SCHLESINGER University of North Carolina

Chapel Hill, NC 27514 U.S.A.



laws and other worldsby fred wilson

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