As we have seen last time, Kant’s problem in the Critique of Pure Reason is that of the possibility of synthetic a priori judgements. We have discussed what synthetic a priori judgements are and why they are important. How does Kant continue from here on out? Kant’s plan is to examine knowledge. He recognises two sources that are fundamental to knowledge: sensibility and understanding. Knowledge requires us to experience objects and to think about the objects we experience. This experience is given by our senses; we see, hear, taste, smell and feel. By thinking we apply concepts to the things that we experience. We can judge that what we see is a pen, that this pen is blue, and so on. In the Critique, Kant examines these two sources of knowledge separately. The transcendental aesthetics examines sensibility; the transcendental logic examines understanding. 

What is transcendental aesthetics?

Where did Kant get his title from? What is transcendental aesthetics? Let’s start by going over aesthetics. In this context, aesthetics has nothing to do with arts. Rather, Kant used the word aesthetics in a sense which it has now lost. Aesthetics, in this context, refers to sensation and sensitive perception. Therefore Kant thought it would be an appropriate name for the part of his book which deals with sensibility and perception. 

What about the word transcendental? Kant's goal was to establish a transcendental philosophy. Such a philosophy relies on knowledge that is not empirical nor is it rationalist speculation. Transcendental knowledge is concerned with the necessary conditions for the possibility of experience. Therefore, transcendental philosophy is concerned with the possibility of a priori knowledge. For example, Kant will establish in the transcendental aesthetics that space and time are conditions for the possibility of experience and that they are necessary in order to have mathematics and physics. Transcendental philosophy should put limits on human knowledge. This should ensure that we will not try to understand more than is possible.

Kant’s vocabulary

It is very important to understand Kant’s vocabulary before diving into the transcendental aesthetics:

1. Sensibility. According to Kant: “The capacity for receiving representations (receptivity) through the mode in which we are affected by objects, objects, is called sensibility.” Sensibility is the passive faculty that receives data from the world. It lets things appear to us. For example, if we see a red apple, our eyes see a colour. The eyes passively receive a representation.

2. Intuition. According to Kant: “In whatsoever mode, or by whatsoever means, our knowledge may relate to objects; it is at least quite clear that the only manner in which it immediately relates to them is by means of an intuition.” This means that intuition is an immediate relation between knowledge and an object. If we go back to the red apple, the actual seeing of the red apple is an intuition. I have a visual intuition of a red apple. However, this intuition is pre-conceptual. I have not yet applied any concepts (“red”, “apple”, “round”) to what I see. 

3. Phenomenon. “The undetermined object of an empirical intuition is called a phenomenon.” This means that in the example mentioned above, it is the apple that is the phenomenon. But as it is given in intuition, this apple is not yet understood as an apple.

A priori forms of sensibility

The goal of the transcendental aesthetics is to show that space and time are a priori forms of sensibility, also called pure intuitions. Kant argues that there must be pure intuitions in order for synthetic a priori judgements to be possible in mathematics, physics and geometry. 

For example, we know that geometry has synthetic a priori knowledge. This has been established in the introduction. We know that this knowledge is a priori because it is necessary and universal. We know that this knowledge is synthetic because it does not merely explain concepts but also goes beyond them. What is this knowledge founded on?

Firstly, because this knowledge is synthetic, we can rule out understanding as its sole foundation. Understanding, on its own, cannot go beyond the concepts it thinks of. There is nothing in understanding which can justify combining one concept with another. This justification comes from sensibility. By seeing that my pen is blue, I can now justify the judgement “my pen is blue”. What we are looking for is not a concept but an intuition. Secondly, because this knowledge is a priori, its source also has to be independent of experience. If its source was experience, then the knowledge would also have to be a posteriori. 

What is space?

Because the analysis of space and time follows the same structure, I will only focus on the analysis of space in this blog post. Kant's argumentation goes as follows: for geometry to have synthetic a priori knowledge, space must be so and so, and since geometry does have synthetic a priori knowledge, space is just as I described.

Kant first argues that space is not empirical. Space is not derived from experience; rather, it is a pure form of intuition. The main argument is that space is not an object among other objects. I can see an apple, a pen and a book, but I can not imagine that I see space next to these items. What I can see is an empty space, but this is not space as such. We might object that while space is not an object among other objects, space is still empirical because it is derived from experience. According to this argumentation, by having experiences and seeing distances and spaces between objects in experience, we can derive a concept of space from these experiences. Kant refutes this argumentation because these experiences of space already presuppose that space is given as a pure intuition. Space is not derived from these experiences; rather, it is what founds these experiences. And to further show that space is not determined by the relations between objects, Kant adds another argument. It is possible to represent a space without objects, an empty space, but it is not possible to represent an object without space. This means that space makes it possible to represent objects. I cannot represent an object outside of space. It’s simply impossible! However, it is possible to represent a space without objects. This means that space can not be determined by objects. Therefore, space is a priori.

Secondly, Kant argues that space is not a concept; rather, it is an intuition. This is because we can only represent one single and unique space. This singularity is supposed to guarantee that it is an intuition and not a concept. According to Kant, whenever we think of multiple spaces, we think of space inside one unique space. For example, my room is a space in my house, my house is a space in the street, but eventually, all spaces are part of space. This space is one and unique. Kant has a second argument for the intuitivity of space: it’s infinitely big. This means that space can not be a concept because concepts do not have sizes.

Transcendental idealism

Transcendental idealism is part of Kant’s theory of experience. The idea is that we do not experience things as they are in themselves but only as they appear to us. Those appearances are given to us in space and time, but things in themselves, independent of the mind, are not in space and time. Isn’t this absurd?

Kant doesn’t think so. What pushes Kant to this transcendental idealism is the fact that space and time are pure intuitions. Space and time therefore are not derived from the world. If space and time are a priori intuitions, then there is no reason to assume that space and time actually exist outside of our minds. If space and time do not exist outside of our minds, that means that things, as they are in themselves, are not determined by space and time. Space and time form how we have experienced things in our minds, but they do not exist outside of our minds. 

 

 

Reading Kant is difficult. If any of the terms used in this post are not clear, be sure to check out my glossary.