Critique of Pure Reason – Transcendental Aesthetic

A short preface of terms from the Transcendental Logic

Though not apart of the Transcendental Aesthetic, some of the terms found in the Transcendental Logic make it easier to understand the the chapter. For Kant, knowledge is derived from two fundamental sources of our mind:


Received representations, or that which refers to objects immediately.


The catagorisation of representations.

In the former the object is given to us, while in the latter the object is thought of by us. Intuition and concepts therefore constitute the elements of our knowledge. Both are needed to have knowledge. Without intuition, concepts would be empty and void. Without concepts, intuition would be unintelligible to us. Both are either pure or empirical.


This refers to something containing sensation.


When no sensation is mixed with the representation.


The effect produced by an object upon the capacity for representation.

Pure Intuitions and Pure Concepts contain only the mechanisms in which  intuitions and concepts can occur. They are possible a priori. Empirical Concepts and Intuitions meanwhile are possible a posteriori.


The receptivity of our mind to receive representations.


The facility of producing representations by ourselves, or the spontaneity of knowledge.

Kant further distinguishes between two more categories.


The science of the rules of sensibility in general.


The science of the rule of understanding in general.

Introduction to the Transcendental Aesthetic

Intuition only takes place insofar as an object is given to us. This is only possible for human beings when the mind is affected in a certain way. Objects are given through the means of our sensibility. Sensibility makes it possible to have intuitions. These intuitions are thought through the understanding, and from the understanding they arise there as concepts. Here are a few more terms:


Undetermined object of an empirical intuition.


An appearance that refers to an object through sensation.


The mechanisms which allow appearance to be ordered in certain relations.

While the Matter is a posteriori, the Form is a priori. Representations are Pure when no part of them belong to sensation. Pure Intuition refers to the pure form of sensibility i.e. the innate mechanisms which allow us to receive representations. Our ability to perceive phenomena exists a priori. The science of all principles of a priori sensibility Kant calls the transcendental aesthetic.

Metaphysical Exposition of the Concept of Space

Via the means of the outer sense, we represent to ourselves objects outside of us. This is done in their shape, size or an object’s relation to another. Inner sense meanwhile refers to how the mind is able to recognize itself and its inner state. Our inner determinations are represented in relations of time. For Kant, time cannot be intuited externally any more than space than can be intuited as something within us.


A distinct (though not comprehensive) representation of what belongs to a concept.

Kant argues that space is not an empirical concept which has been derived from outer experiences. For it to be possible to distinguish a number of sensations outside of myself, I must be able to differentiate where they are positioned. Otherwise, I could not distinguish between one representation and another as everything would be a meaningless blur. Space must already have a basis in our understanding, in order to position and distinguish sizes, shapes, distances, etc. Space is also necessarily an a priori representation which maps all outer positioning of objects. It is impossible to think of a representation which has no space, though we can think of space without objects. Space is then the condition of the possibility of appearances. It is a pure intuition, which allows us to make sense of the world outside ourselves and the objects we become acquainted with in its realm. It is also represented as an infinite given magnitude in our experience.

Transcendental Exposition of the concept of space

By Transcendental Exposition, Kant argues that the explanation of a concept is a principle, in which the possibility of other synthetic a priori knowledge can be understood. For this purpose (1) knowledge of this kind actually flows from a given concept and (2) that this kind of knowledge is only possible under the presuppositions of a given mode of explaining the concept. Kant uses the example of geometry, which explains the properties of space synthetically yet through the means of a priori. For Kant, Space must start as an intuition and not a concept. His reasoning for this is that it is impossible to obtain propositions in this regard which go do not beyond the concept. The intuition must be however prior to any conception of the object and must therefore be pure, not empirical. His reasoning for this is that all geometrical propositions are connected with the consciousness of their necessity.

If there was only two objects in an empty space for example, it is necessary that they would be an equal distance from each other, no matter how far they were apart from each other.

Conclusions from the above concepts

Space does not represent any property of the thing in itself. It is nothing more than the mechanism which allows appearances to occur in the outer senses. It is only through a human standpoint, i.e. our first person subjective perspective, which we can talk about space. It does not show us the things in themselves, but only their appearances which we perceive in our mind.

Metaphysical Exposition of the Concept of Time

Time is not an empirical concept that is derived from experience, for neither simultaneity nor succession would enter our perception if the representation of time did not underlie them a priori. Time is also a necessary representation that underlies all our intuitions. It is a priori. The succession of events in time cannot be derived from experience, but is a priori.

Conclusions from these concepts

Time is not something that exists in itself, or which adheres to an objective determination. It is a purely subjective phenomenon made by our own understanding. It is nothing more than the form of the inner self i.e. our intuitions of ourselves and our inner states. It is not determined by outer appearances of things. It is also the formal a priori condition of appearances in general. While space is restricted to the realm of outer appearances, time is not. It mediates between the inner and outer realms, unlike space which is confined purely to the outer realm. We do not view our self as an object in space, yet we do view our selves in a succession of events in time. If we were to take away the space found in the outer realm however, time becomes nothing because time only has objective validity in respect of appearances.


Alterations are only possible in time, and therefore must be something real. Time is real, but it is not an object. Rather it is a way of representing objects to yourself. It shows what is empirically real but it does not show the absolute realness outside itself. Time and Space are two sources of knowledge which are shown to be synthetic, via not being bound to a single concept. They are ways of putting concepts and intuitions into context. They are also a priori, by not being found in the empirical world but instead, being functions of understanding it.

General Observations of the Transcendental Aesthetic

Appearances cannot exist in themselves, but only through us. The appearance of a body does not exist in itself, it is rather a representation of a thing which exists in us. Kant argues even if Space and Time were things in themselves, many of the phenomena we experience through them would still be a priori synthetic, like geometry.

Consciousness of itself, is simply the representation of the ‘I’. This ‘I’ requires inner perception. In the faculty of becoming conscious of oneself, it must seek to apprehend what is in the mind and only through this can it gain an intuition of itself. Objects that appear are not illusions for Kant, for it is through ourselves and our innate mechanisms that make the world intelligible, in which we give objects an ascription i.e. something that is actually given.