Naturalized epistemology (a term coined by W. V. O. Quine) is a collection of philosophic views concerned with the theory of knowledge that emphasize the role of natural scientific methods. This shared emphasis on scientific methods of studying knowledge shifts focus to the empirical processes of knowledge acquisition and away from many traditional philosophical questions. There are noteworthy distinctions within naturalized epistemology. Replacement naturalism maintains that traditional epistemology should be abandoned and replaced with the methodologies of the natural sciences. The general thesis of cooperative naturalism is that traditional epistemology can benefit in its inquiry by using the knowledge we have gained from the cognitive sciences. Substantive naturalism focuses on an asserted equality of facts of knowledge and natural facts.

Objections to naturalized epistemology have targeted features of the general project as well as characteristics of specific versions. Some objectors suggest that natural scientific knowledge cannot be circularly grounded by the knowledge obtained through cognitive science, which is itself a natural science. This objection from circularity has been aimed specifically at strict replacement naturalism. There are similar challenges to substance naturalism that maintain that the substance naturalists' thesis that all facts of knowledge are natural facts is not only circular but fails to accommodate certain facts. Several other objectors have found fault in the inability of naturalized methods to adequately address questions about what value forms of potential knowledge have or lack.