the interpretation of quantum mechanicsby michael audi
TRANSCRIPT
Philosophical Review
The Interpretation of Quantum Mechanics by Michael AudiReview by: Nancy CartwrightThe Philosophical Review, Vol. 86, No. 3 (Jul., 1977), pp. 394-396Published by: Duke University Press on behalf of Philosophical ReviewStable URL: http://www.jstor.org/stable/2183792 .
Accessed: 28/06/2014 07:49
Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp
.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].
.
Duke University Press and Philosophical Review are collaborating with JSTOR to digitize, preserve and extendaccess to The Philosophical Review.
http://www.jstor.org
This content downloaded from 91.220.202.46 on Sat, 28 Jun 2014 07:49:02 AMAll use subject to JSTOR Terms and Conditions
BOOK REVIEWS
problems it raises. Hume defends common sense but, we are told, "goes on to demolish the traditional modern conceptions of substance" (p. 135). Capaldi does not seem to appreciate just how closely Hume's account of the genesis of the belief in substance is modelled on his account of the vulgar belief in the existence of body. This embarrasses Hume, who would like to distinguish such a commonsensical belief from the fancies of the ancient philosophers, and should have been discussed by Capaldi in connection with his attempt to defend Hume against the charge that his descriptive theory provides no warrant for any normative conclusions. A crucial issue here is whether Hume offers, or should offer, a naturalistic epistemology or simply a naturalistic theory of belief. I find no clear treatment of this question in Capaldi's book.
A final point: this loose talk about "demolishing" the notion of substance seems to reflect the popular view that Hume is fond of showing certain terms to be meaningless. In fact, he goes in for this a good deal less than is often imagined. There is a systematic reason for this. Incoherent ideas, he holds, cannot become the objects of belief, and a central concern of his science of man, in its epistemological moments, is to explain how beliefs involving the conceptions he dis- cusses arise in the first place. To understand how he hopes to accommo- date a notion like "substance" would require coming to terms with his difficult theory of "fictions," something Capaldi does not do.
I should not conclude such a critical review without saying that I found some good things in Capaldi's book. In particular, he argues force- fully against those commentators who dismiss much of the "Treatise" out of hand as misplaced armchair psychology and thus preclude their giving any coherent overall account of Hume's philosophy. In attempt- ing such an account, Capaldi has tried to fill a gap that needs filling, but I am not convinced that he has succeeded.
MICHAEL WILLIAMS
Yale University
THE INTERPRETA TION OF QUANTUM MECHANICS. By MICHAEL
AUDI. Chicago and London, University of Chicago Press, 1973. Pp. xiv, 200. $11.50.
Michael Audi's sensible book addresses important and controversial
394
This content downloaded from 91.220.202.46 on Sat, 28 Jun 2014 07:49:02 AMAll use subject to JSTOR Terms and Conditions
BOOK REVIEWS
issues; yet it can be understood by those who are not expert in the field. Audi has an interesting thesis, and he writes clearly. The chief defect of The Interpretation of Quantum Mechanics is that it is scornful of its oppo- sition and correspondingly cavalier in its arguments, both pro and con. The book is largely a defense of classical particles. In quantum mechanics particle trajectories are not predictable from antecedent circumstances; but, argues Audi, there is no evidence for the stronger claim that particles do not have trajectories. To use the words of G. E. M. Ans- combe, trajectories may be determinate even though they are not determined.
The central argument is given in Audi's analysis of the two-slit experi- ment-one of the few technical discussions in the book. Traditionally the interpretation which results from this experiment is taken to show that no particle passes entirely through either slit. Audi assumes, to the contrary, that every particle has a well-defined trajectory that takes it through either the top slit or the bottom. He reproduces the inter- ference effects by a clever treatment of the potentials acting on the particles at the slits. The idea is due to Alfred Lande. It has been advocated long and polemically by Popper and his students; but nowhere else has it been so explicitly developed. Audi's analysis ought to have appeared in a journal for assessment on its own.
Much of the rest of Audi's book is too sketchy to be of working value. Consider, for example, the proposal that a deterministic theory must preserve information. Audi uses this to tackle Ernest Nagel's thesis that quantum mechanics, though indeterministic for individual variables, is deterministic for states. Nagel bases his claim on the fact that the Schroedinger equation fixes the state at one time, given the state at any other. Audi urges that Nagel is wrong about determinism in quantum mechanics, for deterministic changes must be information preserving. But he does not define information. Using von Neumann's well-known characterization, however, (in terms of quantum entropy) information is preserved in normal Schroedinger evolution. It is not preserved in discontinuous reductions of the wave packet, as might occur for example in measurement, but Nagel never claimed those changes to be deterministic.
Audi has the orientation of a physicist, and his discussions are usually set in physical contexts. This makes his book a nice complement to the abstract work of Kochen and Specker, Fine, van Fraassen and others on the same issue. His informed but nontechnical presentation should have made it ideal as a text in a philosophy course. I did not find it so. Philosophy students could not recognize the difference be- tween controversial and noncontroversial claims; and physics students,
395
This content downloaded from 91.220.202.46 on Sat, 28 Jun 2014 07:49:02 AMAll use subject to JSTOR Terms and Conditions
BOOK REVIEWS
who could, tended to dismiss the controversial claims because they were inadequately defended. It was often possible to construct arguments to defend Audi's views; but these depended more on the inventiveness of the instructor and students than on clues provided by Audi.
NANCY CARTWRIGHT
Stanford University
LAWLIKENESS, ANALOGY, AND INDUCTIVE LOGIC. By JUHANI
PIETARINEN. Amsterdam, North-Holland Publishing Company, 1972. Pp. 143. Hfl. 30.00.
This monograph discusses quantitative systems of inductive logic in which problems of lawlikeness and analogy may be treated. The prob- lem of lawlikeness is taken to be the question how appropriate probability assignments are to be made to generalizations; the problem of analogy concerns the conditions under which evidence concerning predicates not in a sentence is relevant to its confirmation. The best known example of the latter is the time variable in Goodman's new riddle of induction. A large portion of the book summarizes technical developments due to Carnap and Hintikka and related philosophical problems, a few sections present new technical innovations and new philosophical arguments.
In The Continuum of Inductive Methods Carnap proposed a family of inductive systems depending on a parameter X. The value chosen for X determines the relative weight of evidence versus the initial probability when the probability of a hypothesis on evidence is considered. For example, suppose we are concerned with the prediction that the next observed object a will be an F, and the evidence is that m/n past objects have been F. The choice of X determines which probability between the prior probability of Fa and m/n is assigned to Fa on the evidence. 1 One feature of Carnap's systems, regardless of the choice of X, is that although the probability of (x) Fx is sometimes nonzero in finite universes, in an infinite universe any nontrivial generalization has zero probability. Hintikka has proposed a method for languages containing only one family of predicate2 of adding another parameter a in such a way that
1 More accurately, the choice of X affects the initial distribution of prob- abilities from which all conditional probabilities are derived.
2 A family of predicates is a set of exclusive, exhaustive predicates; dif- ferent families are assumed to be logically independent.
396
This content downloaded from 91.220.202.46 on Sat, 28 Jun 2014 07:49:02 AMAll use subject to JSTOR Terms and Conditions