Imagine an atheist who believes—against religious dualism—that there is one world, not two, and that it runs on determinate physics (or on perfect quantum probabilistic randomness, which amounts to the same thing). Now also imagine that he (or she) believes in free will.
Free will, of course, is a religious concept. It is a concept that derives from religious dualism. Atheism is a monism—a philosophy of one world that reduces to atoms and void—and if an atheist believes that the universe goes on mechanistic laws then that same atheist must (logically) think of free will as ultimately an illusion. If the universe is physics and chemistry, and there is no second world, then what is going on at the level of human free will is not primary or determinative of anything that is happening in the universe. It just appears to be so.
Of course, very few atheists face monistic determinism (or its practical equivalent, quantum statistical randomness) squarely. Most are in cognitive dissonance about it. They expect the courts to continue to apportion blame, and they expect their wives and husbands to choose them freely over other lovers. They expect, in other words, a ghost in the machine to still move things around, and still be responsible for moving things around.
For an atheist, free will functions like redemption does for a Christian: it is a comforting thought with no empirical basis. It is nice to believe, and reduces your subjective anxiety, but if monism is true then free will is almost certainly not true.
But if someone out there can explain to me how, in a monistic universe that otherwise “goes” by either determinate or quantum probabilistic atoms rustling in the void, human free will nevertheless can be efficacious—and not just appear to be so—I’d love to learn. I’m an agnostic. I think that God is either dead or not talking. So I’m open to a really good free will argument on monistic assumptions. I want to believe in free will, so set me straight about this.