The new way of thinking about law, introduced by Immanuel Kant, has a surprising affinity with the philosophies of both Aristotle and Hobbes. For Kant derives his view of law from the requirements of moral integrity, but does so without appealing to either revelation or transcendent metaphysics. Kant has accordingly been acclaimed as the founder of the modern philosophy of law. Yet he has also been charged with having no philosophy of law.

Both reputations are plausible because Kant saw human beings as inhabitants of two wholly distinct worlds. On the one hand, their bodily existence makes them components of the natural, empirical world where all objects are moved by causes external to themselves. In this respect, human beings are mechanisms whose operation is determined by sensory stimuli in accordance with the laws that govern the natural world. But on the other hand, human beings are rational persons. They are not only capable of exercising “theoretical reason” to discover, as Newton had, the laws of the natural world, but they are also possessed of “practical reason,” which enables them to choose which purposes to pursue by means of utterances and actions without reference to contingent wants or circumstances. Human beings are consequently distinguished by the “freedom” to choose and to act as they “will.” Their frequent lack of power to achieve their purposes does not qualify this “freedom.” And their conduct cannot be said to be directed to their achievement of a single comprehensive end, such as “happiness.”