What is Naturalism?

British philosopher Timothy Williamson on why "naturalism as dogma is one more enemy of the scientific spirit."

Many contemporary philosophers describe themselves as naturalists. They mean that they believe something like this: there is only the natural world, and the best way to find out about it is by the scientific method. I am sometimes described as a naturalist. Why do I resist the description? Not for any religious scruple: I am an atheist of the most straightforward kind. But accepting the naturalist slogan without looking beneath the slick packaging is an unscientific way to form one’s beliefs about the world, not something naturalists should recommend.

What, for a start, is the natural world? If we say it is the world of matter, or the world of atoms, we are left behind by modern physics, which characterizes the world in far more abstract terms. Anyway, the best current scientific theories will probably be superseded by future scientific developments. We might therefore define the natural world as whatever the scientific method eventually discovers. Thus naturalism becomes the belief that there is only whatever the scientific method eventually discovers, and (not surprisingly) the best way to find out about it is by the scientific method. That is no tautology. Why can’t there be things only discoverable by non-scientific means, or not discoverable at all?