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.
Comment: This text provide an in-depth overview and critique on Quine's perspective on modality and it would be crucial in postgraduate courses of philosophy of science and logic. Previous knowledge on Quine, modality and quantum mechanics is needed.