In discussing atheism with atheists I’ve noticed that there is a good deal of resistance on their part whenever I claim that atheism, logically, is in the possession of a positive ideology: naturalism. No, they will say, an atheist is just someone who sees no good reasons to take any of the claims of religious believers seriously. It is the religious believers who make wild claims about the nature of the universe and the existence of gods, and it is the atheist who, asking for positive evidence for their claims, and receiving none, moves on. That’s all an atheist is. Nothing more. Atheists also can’t prove that Bertrand Russell’s teapot is orbiting Uranus, but that doesn’t mean that we are in possession of a positive and hostile anti-teapot ideology known as “anti-teapotism.” We just see no good reasons to think that teapots orbit Uranus or that invisible gods orbit the heavens.
But clearly this response is mendacious, for while it is true that atheists cannot prove that gods don’t exist—you can’t prove a negative—this doesn’t mean that a rejection of theistic explanation doesn’t have a consequence: it means that you must, by necessity of logic, have the positive belief that the universe consists of matter—atoms and void—and nothing else.
But this too is a claim—a thesis—that exceeds the empirical, for the universe appears not just to be made of material, it also appears as if it might have some sort of mind or telos behind it (the laws of physics being one example of this appearance). In other words, atheism cannot be the default “king of the hill” starting point upon which positive claims about the existence of gods are to be judged, for the atheist is in possession of his (her) own very definite thesis: the universe is atoms and void and nothing else.
And so atheism is not just the rejection of belief in gods. It is the positive claim, itself not subject to empirical verification, that the universe consists of matter.