Naturalism comes in many varieties, but the entry-level union card—the famous empiricist David Hume is our hero—expresses solidarity with this motto: “Just say no to the supernatural.” Rebirths, heavens, hells, creator gods, teams of gods, village demons, miracles, and divine retribution in the form of plagues, earthquakes, and tsunamis are things naturalists don’t believe in. What there is, and all there is, is natural stuff, and everything that happens has some set of natural causes that produce it—although we may not be able to figure out what those causes are, or were.
Why be a naturalist? World historical evidence suggests that naturalism, vague as it is, keeps being vindicated, while the zones “explained” by the supernatural get smaller everyday. Naturalism is a good bet.
From Buddhism Without the Hocus-Pocus by Owen Flanagan, professor of philosophy at Duke University