Naturalism is the stance that everything that exists in the universe arises from "natural" causes, of the sort observable by science -- not supernatural ones. It's practically a foundational tenet of skepticism. But does it imply that there can be no meaning, or purpose, or morality in the universe? This episode features physicist Sean Carroll, author of the recent bestseller The Big Picture: on the Origins of Life, Meaning and the Universe Itself. Sean and Julia talk about the new "ism" he introduces in the book, "poetic naturalism," and how it attempts to resolve the apparent conflict between science on the one hand, and things like morality, free will, consciousness, and meaning on the other.