ABSTRACT
Pages i-iii-The different branches of philosophy The three main branches of philosophy are logic, physics, and ethics. Of these logic is formal: it abstracts from all differences in the objects (or matter) about which we think and considers only the necessary laws (or forms) of thinking as such. Since it borrows nothing from our sensuous experience of objects, it must be regarded as a wholly non-empirical or a priori science. Physics deals with the laws of nature, and ethics with the laws of free moral action. These two philosophical sciences deal therefore with objects of thought which are sharply distinguished from one another.
