We discuss recent work in experimental philosophy on free will and moral responsibility and then present a new study. Our results suggest an error theory for incompatibilist intuitions. Most laypersons who take determinism to preclude free will and moral responsibility apparently do so because they mistakenly interpret determinism to involve fatalism or “bypassing” of agents’ relevant mental states. People who do not misunderstand determinism in this way tend to see it as compatible with free will and responsibility. We discuss why (...) these results pose a challenge to incompatibilists. (shrink)