Kant Has Shifted My World from the Metaphysical to the Practical

It's so much harder than I think to write something about Kant's philosophy. My level of English writing capability is also not as good as I thought. So instead of trying to write a full (or even brief) introduction to Kant's influential ideas, I should just use the simplest English to record my understanding and feeling about Kant's transcendental idealism.

Firstly, Kant proves the certainty of the external world, by pointing out the relationship between existence, time and space. He believes that existence is spatiotemporal, meaning that existence must be measured by time (i.e. when does it exist and for how long), and time can only be experienced against something external to us. Our consciousness alone, without body and any outside material objects, cannot experience time directly. Therefore, a material world must exist outside of me.

Secondly, Kant combines rationalism and empiricism by examining two elements of human perception: sensibility and understanding. In order to be aware of/ acquainted with a particular thing, our mind must use both of the two elements. And each element has two sides. Sensibility involves the intuition of a particular thing in space and time, and the intuition of space and time. Understanding involves the concept of a particular thing and the concept of a 'thing'. The use of both sensibility and understanding is necessary for human perception to be possible. So basically, before Kant, rationalism stresses the use of understanding and empiricism emphasises sensibility. But now Kant has sythesised both traditions into his transcendental idealism.

Lastly, the consequence drew from the second point is that our perception of the world relies on our intuition of space and time, and our concept of substance. These fundamental ideas preceding all other knowledge are what rationalists termed the a piori knowledge, meaning they must first exist in our mind before experience. However, time and space and other a piori knowledge are essentially human features that are products of the mind. These a piori ideas are not things, and therefore are not experienced by material object. Therefore, it leads to a significant consequence: the world could be divided into two: first is the world we experience or the phenomenal world; second is the world of things-in-themselves or the noumenal world which we have not and will never be able to gain any knowledge from.

This means a world to me. Since I'm naturally inclined to wonder the nature of the world (I even second Plato's allegory of the cave), Kant's philosophy has shifted my mind from the mystical metaphysical realm back to reality. He doesn't just say it's meaningless to think about metaphysics, instead he believes that even if there is a world of truth beyond human conception, this world is unknowable because of the nature of human perception.

Immanuel Kant is said to be one of the most influential figure in the history of western philosophy. I can see the face of philosophy has changed since Kant. Philosophers no longer linger in metaphysics. The center seems to have been shifted to more practical areas, such as ethics, philosophy of language and philosophy of science. This also happens to me on an individual level. What remains compelling to me is practical things in this phenomenal world. We're certain that the outside world is real. Even if this 'real' only exists in our experienced world, it's the only knowable world left to us. So I should learn everything practical to improve my life and everyone else's. Therefore, much of the most valuable knowledge now exist outside of philosophy, such as healthcare, medicine, fitness, cooking, technology, etc.

A list of practical knowledge in philosophy for your reference:

Traditions:

Existentialism

Pragmatism

Phenomenology

Branches:

Ethics

Philosophy of language

Philosophy of science

Philosophy of education

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