My practice as a scientist is atheistic. That is to say, when I set up an experiment I assume that no god, angel or devil is going to interfere with its course; and this assumption has been justified by such success as I have achieved in my professional career. I should therefore be intellectually dishonest if I were not also atheistic in the affairs of the world.
-- J.B.S. Haldane
This is an argument that people who practice or accept science ought to be atheists, and it has been endorsed recently by Lawrence Krauss. But what is the argument exactly? Here numbered premises might be nice.
1. In setting up experiments in science, scientists set aside the possibility of divine interference changing the result of the experiment.
2. To be consistent, therefore, someone who practices science ought also to discount the possibility of divine interference in all areas of life.
3. To discount the possibility of divine activity in the world in all areas of life is to be, at least in practice if not in theory, an atheist.
4. Therefore consistent thinking on the part of scientists leads to atheism.
But I fail to see why I should believe 2. If I ask a scientist about whether or not a hundred dollar bill will remain in my drawer if I leave it there, the scientists might answer "yes." By this I take it he would mean that the bill did not have properties that will cause it to disintegrate there, or spontaneously combust. . But he doesn't know whether a burglar might get into the drawer. In other words, the scientist is going to tell me what will happen to the bill left to itself. It is mapping the world apart from interference, telling you what will happen all things being equal. But it is a further question as to whether all things are equal.