Critique of Pure Reason

Intuition is the direct cognition of an object. It is opposed to conception (the making of concepts) in that it is receptive to the outer world, not active upon it. Human intuitions, Kant claims, are always sensible, that is, of sensation. There are two essential forms all our intuitions require: space and time.

The “Transcendental Logic” is the longest and most involved part of the Critique. It is the science of the rules of the possible use of the capacity of understanding. The understanding is a faculty of the mind, which, for Kant, involves the active capacity of the mind to form concepts (through general categories) in conjunction with our intuitions of objects. Transcendental logic is a field of philosophical study that details the nature of the faculty of understanding so that we have knowledge of all its functions and limitations.

Presentation (from the German word Vorstellung, often translated as “representation”) is the most general way of an object’s appearance before consciousness. All presentations are of appearances, not things “in themselves.” One of Kant’s projects in the Critique is to understand the various ways objects appear before consciousness and how those presentations ought to be classified.

The doctrine of the schematism is one of the most enigmatic in the Critique. It details the rules via which the categories of the understanding are consistently applied to objects of experience. It proceeds from the understanding through the capacity of the (productive) imagination to sensible experience of the world. Its function is necessary for consistent and constrained experience of objects.

Sensibility is the capacity of the human mind to be affected by given objects. It deals with the human ability to receive data from the outside world, through the sense organs, for instance. The forms of sensible intuition (space and time) are the absolute limits within which all objects are given.

The so-called “thing-in-itself” is the transcendental object, which exists beyond any human experience of it. It is impossible to have any direct awareness of these things (if they even exist) because all human perception is necessarily of appearances before consciousness. The “thing-in-itself” is a (problematic) object of the noumenal realm, whereas all human experience takes place within the phenomenal realm of appearance.