Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic tradition, recognized as "one of the most influential philosophers of the twentieth century". From 1930 until his death 70 years later, Quine was continually affiliated with Harvard University in one way or another, first as a student, then as a professor. He filled the Edgar Pierce Chair of Philosophy at Harvard from 1956 to 1978. Quine was a teacher of logic and set theory. Quine was famous for his position that first order logic is the only kind worthy of the name, and developed his own system of mathematics and set theory, known as New Foundations. In philosophy of mathematics, he and his Harvard colleague Hilary Putnam developed the Quine–Putnam indispensability argument, an argument for the reality of mathematical entities. However, he was the main proponent of the view that philosophy is not conceptual analysis, but continuous with science; the abstract branch of the empirical sciences. This led to his famous quip that "philosophy of science is philosophy enough". He led a "systematic attempt to understand science from within the resources of science itself" and developed an influential naturalized epistemology that tried to provide "an improved scientific explanation of how we have developed elaborate scientific theories on the basis of meager sensory input". He also advocated ontological relativity in science, known as the Duhem–Quine thesis. His major writings include the papers "On What There Is" (1948), which elucidated Bertrand Russell's theory of descriptions and contains Quine's famous dictum of ontological commitment, "To be is to be the value of a variable", and "Two Dogmas of Empiricism" (1951), which attacked the traditional analytic-synthetic distinction and reductionism, undermining the then-popular logical positivism, advocating instead a form of semantic holism. They also include the books The Web of Belief, which advocates a kind of coherentism, and Word and Object (1960), which further developed these positions and introduced Quine's famous indeterminacy of translation thesis, advocating a behaviorist theory of meaning. A 2009 poll conducted among analytic philosophers named Quine as the fifth most important philosopher of the past two centuries. He won the first Schock Prize in Logic and Philosophy in 1993 for "his systematical and penetrating discussions of how learning of language and communication are based on socially available evidence and of the consequences of this