 Philosophers have long thought that some truths were necessary while others were contingent; in the twentieth century, under the influence of logical positivism, this was taken to be the distinction between those statements that were “true in virtue of meaning” (hence necessarily true) and those that were “true in virtue of fact” (hence only contingently true). The former “analytic” truths were the proper domain of philosophy; the latter “synthetic” truths the proper domain of empirical science. Quine argued that the distinction could not be sustained: all statements are, in principle, answerable to experience, and, conversely, all statements can be maintained in the face of experience as long as we adjust other parts of our picture of the world. So there is no hard distinction between claims that are “true in virtue of meaning” and “true in virtue of facts,” or between “necessary” and “contingent” truths; there is simply the socio-historical fact that, at any given point in the history of inquiry, there are some statements we are unlikely to give up in the face of recalcitrant empirical evidence and others that we are quite willing to give up in light of new empirical evidence.