 This encyclopedia entry is about the free will/determinism problem; more specifically, it is about arguments for the claim that free will is incompatible with determinism. Since so much of the contemporary free will literature is dominated by concerns about moral responsibility, some of the arguments considered will be arguments for the thesis that if determinism is true, we are never morally responsible because we never satisfy the “freedom requirement” for being morally responsible for our actions. But the focus, in this entry, will be on the question of whether free will (or acting with free will) is compatible with determinism.