“Suppose that the Mind Projection Fallacy was not a fallacy, but simply true. Suppose that a 747 had a fundamental physical existence apart from the quarks making up the 747. What experimental observations would you expect to make, if you found yourself in such a universe? If you can’t come up with a good answer to that, it’s not observation that’s ruling out “non-reductionist” beliefs, but a priori logical incoherence. If you can’t say what predictions the “non-reductionist” model makes, how can you say that experimental evidence rules it out? My thesis is that non-reductionism is a confusion; and once you realize that an idea is a confusion, it becomes a tad difficult to envision what the universe would look like if the confusion were true. Maybe I’ve got some multi-level model of the world, and the multi-level model has a one-to-one direct correspondence with the causal elements of the physics? But once all the rules are specified, why wouldn’t the model just flatten out into yet another list of fundamental things and their interactions? Does everything I can see in the model, like a 747 or a human mind, have to become a separate real thing? But what if I see a pattern in that new supersystem? Supernaturalism is a special case of non-reductionism, where it is not 747s that are irreducible, but just (some) mental things. Religion is a special case of supernaturalism, where the irreducible mental things are God(s) and souls; and perhaps also sins, angels, karma, etc.” (Eliezer Yudkowsky, Rationality)