According to Rationalists (such as Descartes), all knowledge must come from the mind. Rationalism is concerned with absolute truths that are universal (such as logic and mathematics), which is one of the strengths of this position. It's weakness lies in the fact that it is difficult to apply rationalism to particulars (which are everywhere in our daily life!) because it is of such an abstract nature.
According to Empiricists, such as John Locke, all knowledge comes from direct sense experience. Locke's concept of knowledge comes from his belief that the mind is a "blank slate or tabula rosa" at birth, and our experiences are written upon the slate. Therefore, there are no innate experiences. The strength of the empiricist position is that it is best at explaining particulars, which we encounter on a daily basis. The weakness of this position is that one cannot have direct experiences of general concepts, since we only experience particulars.
Noticing that rationalism and empiricism have opposing strengths and weaknesses, Kant attempted to bring the best of both positions together. In doing so he came up with a whole new position, which I will soon explain.
Kant claimed that there are 3 types of knowledge. The first type of knowledge he called "a priori", which means prior to experience. This knowledge corresponds to rationalist thinking, in that it holds knowledge to be...