Extensionalism and Scientific Theory in Quine’s Philosophy

Abstract

In this article, I analyze Quine’s conception of science, which is a radical defence of extensionalism on the grounds that first‐order logic is the most adequate logic for science. I examine some criticisms addressed to it, which show the role of modalities and probabilities in science and argue that Quine’s treatment of probability minimizes the intensional character of scientific language and methods by considering that probability is extensionalizable. But this extensionalizing leads to untenable results in some cases and is not consistent with the fact that Quine himself admits confirmation which includes probability. Quine’s extensionalism does not account for this fact and then seems unrealistic, even if science ought to be extensional in so far as it is descriptive and mathematically expressible.

Acknowledgements

I would like to thank Dr James W. McAllister for his helpful comments and advice and also an anonymous referee for his or her useful remarks.

Notes

[1] Quine transforms singular terms into definite descriptions but he often gives examples of this kind to illustrate the failure of SI and EG. See, e.g., Quine 1963, 139 and 146, 1976a, 188–189, 1983, 145 and 153, and so on.

[2] The idea that this frame could be used to establish a probabilistic calculus has been suggested to me by an anonymous referee whom I thank for useful comments.

[3] The structures are: {1} All objects are F; {2, 4, 5} two objects are F, one is not; {3, 6, 7} one is F two are not; and {8} none is F. Each structure has a probability of 1/4. See Hajek 2009.

[4] As far as I know, there are a few other passages where Quine talks about probability, but they are merely comments on other authors.

[5] This example is analyzed in Vickers 2010.