W.V.O. Quine’s writings were key to the development of American philosophy in the 1950s, 1960s, and 1970s. His landmark works (“Two Dogmas of Empiricism,” “Ontological Relativity,” and Word and Object, for example) provided a very appealing combination of plain speaking, seriousness, and import. Quine’s voice certainly stands out among all American philosophers of his period.
Quine’s insistence on naturalism as a view of philosophy’s place in the world is one of his key contributions. Philosophy is not a separate kind of theorizing and reasoning about the world, according to Quine; it is continuous with the empirical sciences through which we study the natural world (of which humanity and the social world are part). Also fundamental is his coherence theory of the justification of beliefs, both theoretical and philosophical. This theory was the source of John Rawls’s method of reasoning for a theory of justice based the idea of “reflective equilibrium.” This approach depended on careful weighing of our “considered judgments” and the adjustments of ethical beliefs needed to create the most coherent overall system of ethical beliefs.
Philosophically I am bound to Dewey by the naturalism that dominated his last three decades. With Dewey I hold that knowledge, mind, and meaning are part of the same world that they have to do with, and that they are to be studied in the same empirical spirit that animates natural science. There is no place for a prior philosophy. (185).
For naturalism the question whether two expressions are alike or unlike in meaning has no determinate answer, known or unknown, except insofar as the answer is settled in principle by people’s speech dispositions, known or unknown. If by these standards there are indeterminate cases, so much the worse for the terminology of meaning and likeness of meaning. (187)
The implicit maxim guiding his choice of ‘rabbit’, and similar choices for other native words, is that an enduring and relatively homogeneous object, moving as a whole against a constrasting background, is a likely reference for a short expression. If he were to become conscious of this maxim, he might celebrate it as one of the linguistic universals, or traits of all languages, and he would have no trouble pointing out its psychological plausibility. But he would be wrong; the maxim is his own imposition, toward settling what is objectively indeterminate. It is a very sensible imposition, and I would recommend no other. But I am making philosophical point. (191)
These are radical and counter-intuitive conclusions — in some ways as radical as the “incommensurability of paradigms” notion associated with Thomas Kuhn and the critique of objectivity associated with Richard Rorty. What is most striking, though, is the fact that Quine comes to these conclusions through reasoning that rests upon very simple and clear assumptions. Fundamentally, it is his view that the only kinds of evidence and the only constraints that are available to users and listeners of language are the evidences of observable behavior; and the full body of this system of observations is insufficient to uniquely identify a single semantic map and a single ontology.
(Peter Hylton’s article in the Stanford Encyclopedia of Philosophy does a good job of capturing the logic of Quine’s philosophy; link.)