 Why not? The reason, Kant says, is ultimately that the causes of these movements occur in time. Return to the theft example. A compatibilist would say that the thief’s action is free because its proximate cause is inside him, and because the theft was not an involuntary convulsion but a voluntary action. The thief decided to commit the theft, and his action flowed from this decision. According to Kant, however, if the thief’s decision is a natural phenomenon that occurs in time, then it must be the effect of some cause that occurred in a previous time. This is an essential part of Kant’s Newtonian worldview and is grounded in the a priori laws (specifically, the category of cause and effect) in accordance with which our understanding constructs experience: every event has a cause that begins in an earlier time. If that cause too was an event occurring in time, then it must also have a cause beginning in a still earlier time, etc. All natural events occur in time and are thoroughly determined by causal chains that stretch backwards into the distant past. So there is no room for freedom in nature, which is deterministic in a strong sense.