Immanuel Kant was a philosopher responsible for a revolution in philosophy. Kant is an idealist as well as a rationalist philosopher. He tried to conciliate two kinds of schools of thought: the rationalists and the empiricists. For Kant some ideas are innate like the idea of space for example. Without it philosophy wouldn’t be possible at all as well as sciences.
To Kant there are two kinds of knowledge: the a priori knowledge and a posteriori knowledge. The former is concerned with direct predication from the subject for example ‘All bachelors are single’ or a ‘triangle has two angles equal to 90 degrees’.