According to Immanuel Kant, all rational knowledge is either material or formal: the former considers some object, the latter is concerned only with the form of the understanding and of the reason itself, and with the universal laws of thought in general without distinction of its objects. Formal philosophy is called Logic. Material philosophy, however, has to do with determinate objects and the laws to which they are subject, is again twofold; for these laws are either laws of nature or of freedom.