 Quine formulated a methodological critique of traditional philosophy. He suggested a different philosophical methodology instead, which has become known as naturalism (Quine 1969). According to naturalism, our best theories are our best scientific theories. If we want to obtain the best available answer to philosophical questions such as What do we know? and Which kinds of entities exist?, we should not appeal to traditional epistemological and metaphysical theories. We should also refrain from embarking on a fundamental epistemological or metaphysical inquiry starting from first principles. Rather, we should consult and analyze our best scientific theories. They contain, albeit often implicitly, our currently best account of what exists, what we know, and how we know it.