a person is like other mechanical things that are determined in their behavior such as a wind-up toy, a billiard ball, a puppet, or a robot, then people must not have free will. This argument has been rejected by compatibilists such as Daniel Dennett on the grounds that, even if humans have something in common with these things, it remains possible and plausible that we are different from such objects in important ways. Another argument for incompatibilism is that of the "causal chain". Incompatibilism is key to the idealist theory of free will. Most incompatibilists reject the idea that freedom of action consists simply in "voluntary" behavior. They insist, rather, that free will means that someone must be the "ultimate" or "originating" cause of his actions. They must be causa sui, in the traditional phrase. Being responsible for one's choices is the first cause of those choices, where first cause means that there is no antecedent cause of that cause. The argument, then, is that if a person has free will, then they are the ultimate cause of their actions. If determinism is true, then all of a person's choices are caused by events and facts outside their control. So, if everything someone does is caused by events and facts outside their control, then they cannot be the ultimate cause of their actions. Therefore, they cannot have free will. This argument has also been challenged by various compatibilist philosophers. A third argument for incompatibilism was formulated by Carl Ginet in the 1960s and has received much attention in the modern literature. The simplified argument runs along these lines: if determinism is true, then we have no control over the events of the past that determined our present state and no control over the laws of nature. Since we can have no control over these matters, we also can have no control over the consequences of them. Since our present choices and acts, under determinism, are the necessary consequences of the past and the laws of nature, then we have no control over them and, hence, no free will. This is called the consequence argument. Peter van Inwagen remarks that C.D. Broad had a version of the consequence argument as early as the 1930s. The difficulty of this argument for some compatibilists lies in the fact that it entails the impossibility that one could have chosen other than one has. For