Because Space and Time are forms of pure sensitivity as the Critical one of the Pure Reason of Kant? What copernicana revolution in sciences is called, Kant proceeded in the philosophy. In this walked, Kant he substituted the realistic hypothesis, that admits that a reality in either given and the knowledge if adaptando it, registering the Real with passive spirit. The kantiana reply to this question it is the idealistic hypothesis, critical to the empiristas and racionalistas. In the kantiano idealismo, the spirit participates actively in the elaboration of the knowledge, that is, the Real intentionally is constructed. As it affirms in the Critical one of the Pure Reason, ' ' we do not know in the things seno a priori what we ourselves in it colocamos' '. To understand what it means a priori she is necessary to distinguish two classrooms from elements that are objects of the knowledge: the substance of that the objects are facts, at the same time the substance of the knowledge and the ones that depend on the proper citizen, constituting its form.
The substance of the knowledge varies of an object to another one, given a posteriori, depending to receive the impressions by means of the directions. The form is found in all objects for all the citizens, being a priori knowledge finding in the mind its accomplishment. A priori it is expression that indicates the necessary condition for the knowledge of non-separable form. All necessary proposal is a tautology is based only on the laws of the reason. The reason is the universal and necessary source of all the proposals. For example, the proposals of the mathematics are universal and necessary; the relations of cause and effect also. The Critical one of the Pure Reason is a species of inventory of the forms a priori of the spirit while college of the knowledge.
In the college of the knowledge, this is received through sensitivity or college from the intuitions or by the agreement, also called college of the concepts, according to kantiana terminology. In this context, the space and the time are forms a priori of sensitivity, or either, pure intuitions. This wants to say that the space and the time are the characteristic ways for which the spirit perceives the things, where all the things is inserted. The space is the form of the external direction; the time, the form of the internal direction. Space and time are the pure forms of the sensible intuitions in general. That is: all perception is organized under the forms of the espacialidade or of the secular succession, all representation of any object is representation of something given in the space and the time, them two pure forms of the intuition. It occurs that differences exist enter the knowledge a priori. To clarify this difference she is necessary to distinguish the analytical and synthetic judgments between. Analytical it is the judgment that only explana a concept without adhesion of any newness, as for example, ' ' all the bodies are extensos' '. All the bodies have a specific size and nothing it is added of new. On the other hand, synthetic it is a judgment that adds some thing to the concept conceived for a citizen. Example: ' ' this body is pesado' '. This addition of predicate is called of a priori synthetic judgment. One understands that if the intuition is pure the synthesis is a priori.