A few days ago, I had the privilege of attending a lecture by Paul Draper, probably one of the most prominent atheist philosophers of religion today. His lecture had a wealth of ideas (including a proposed solution to Hume's problem!), but I'd like to focus on one tiny piece of the lecture, viz. his argument that the burden of proof is on the theist, and not on the atheist.
Here goes the argument, which Paul was kind enough to discuss with me, prior to posting it. I apologize if there are any remnant misrepresentations.
Let's assume that there are a number of epistemically possible world views: some are naturalistic, some are supernaturalistic, let's even grant there are others (non-supernatural, non-natural, but some third, unknown view). Then we can see that the following diagram exhausts all epistemic possibilities: N (naturalism), S (supernaturalism) and not-N and not-S.
Now let us grant that S and N are equally epistemically modest. There is no clear definition for epistemic modesty, except perhaps a comparative sense: a statement p is epistemically more modest than a statement q if (or iff?) p is less informative than q (e.g., p says I have a car, q says I have a red toyota; p says linda is a bank teller, q says she's a bank teller and a feminist etc.) In the absence of prior information, epistemically modest statements are more likely to be true than epistemically less modest statements.
- S holds that the original cause of the world is mental.
- N holds that the original cause the world is physical.
Thus according to N the physical causes the physical and the mental (except in the case of eliminative physicalism, where the physical only causes the physical). According to S the mental causes the mental and the physical (except in the case of eliminative idealism, where it only causes the mental).
These two world views seem equally epistemically modest to Draper. They both have a burden of proof. Theism (as opposed to supernaturalism more generally) is a much less epistemically modest position than both generic S and N. Theism makes claims about the nature of the supernatural (God is one person, omniscient, omnipotent, perfectly good, etc.) and is thus considerably less epistemically modest than atheism (see figure). Atheism is per definition everything that is not-theism, so it encompasses the entire gray area on the figure. Theism is a small speck in the realm of supernatural epistemic possibilities. So according to Draper, the atheist's burden of proof is lifted. Since the theist argues for a position that is less epistemically modest than the atheist, the theist carries the burden of proof.
My main qualm with this argument is that Draper represents the atheist as the holder of a generic worldview, compared to the epistemically immodest theist. However, I think this is a misrepresentation of how most atheists would view their position. I doubt it if it's a kind of generic view that is in principle compatible with the existence of all sorts of supernatural beings like elves and demons as long as they are not God. I think the atheism that is usually argued for is a form of scientific naturalism, which, like theism is a small part of all epistemic possibilities (it excludes supernaturalism, not-supernaturalism and not-naturalism, and non-scientific naturalism).
Draper concedes that a scientific naturalist does have a burden of proof, but argues that his main point remains that one can be justified in rejecting theism without evidence but one cannot be justified in accepting theism (or any other specific view like scientific naturalism or even naturalism) without evidence.