In epistemology, McGrew works on
foundationalism, internalist and externalist theories of
epistemic justification, theories of rationality,
a priori knowledge, objectivity and relativism, formal and performative self-refutation, perceptual knowledge and the given, and
metaepistemology. His interests in the philosophy of science include models of explanation, simplicity, probability, falsifiability and rational theory choice, history of science and rational reconstruction, logic, realism and contemporary physics, and the mathematics and philosophy of cosmological
fine-tuning. In
probability theory, McGrew has published on induction and statistical inference,
Bayesian confirmation theory, and probabilistic models of explanatory reasoning. His interests in the history of science include
developments in physics among the Muslim scholars of the Middle Ages,
astronomy and dynamics from
Aristotle through
Isaac Newton, particles, waves, the development of
optics between the years 1660 and 1850, the fall of the
ether theory, and the advent of
relativity. In the philosophy of religion, McGrew focuses on historical arguments for and against
miraculous claims,
natural theology and atheology, and ramified natural theology. ==Personal life==