On the Simplicity of Theism vs. Naturalism

Many have suggested that naturalism posits fewer bits of complexity in one's theory, whereas theism posits more items of complexity. Is this true?

To borrow Graham Oppy's shopping cart metaphor, a theist includes in their shopping cart of theoretical posits that there is some sort of supreme being. That's not required in the naturalist's shopping cart. So theists have an item of complexity that a naturalist need not posit.

However, a standard naturalism (e.g., Oppy's naturalism) includes in its shopping cart of theoretical posits these items: that there are natural objects, that there are mind-independent things, and that there are fundamental imperfections (or some description that precludes theism). None of these are required in the theist's shopping cart. So standard naturalism posits three bits of ideological complexity (i.e., complexity of the theory), where theism only posits one. In this respect, theism is simpler theory in this sense: it posits fewer categories.

To be clear, if a theist doesn't posit the category, natural object, she doesn't need to posit the category, non-natural, either. The theist can say instead that there are objects and decline to posit these more special categories.

Also, neither a naturalist nor a theist need to include a "there is nothing else" in their respective theories, since they can simply leave open whether there may be other things.

Relevance: the simplicity of a theory is related to its internal probability. Simpler theories have fewer parts, and thus fewer ways to go wrong. They are thus more probable out of the gate compared with more complicated theories. Suppose theism is indeed a simpler theory compared with the naturalist contender above. In that case, one could argue, contrary to a popular impression, that theism actually starts ahead in terms of being intrinsically more probable (on one measure).

Of course, that doesn't mean that theism is more likely all things considered, or that one couldn't adopt a non-standard naturalism (e.g., one that doesn't posit mind-independent things).

I share additional developments of my thinking about this topic here.