Immanuel Kant: Dare to Think
By: Steven Gambardella
Tags: Culture, Philosophy, Psychology, Science, History

Hume’s Fork

To make his point, Hume had made a distinction between two kinds of judgements. Analytic and Synthetic.

Some judgements we make about things are logically contained in the concept of those things.

For example, “a triangle has three sides” and “a bachelor is an unmarried man”. We could also say “all physical things occupy space.” Those statements are true by definition — self-evidently true — and are not necessarily taking our knowledge about the subject further. They are logically true.

To Hume, these “analytic” statements were useless; they say nothing about the world at all. They are “tautological”: they are true in all instances. An example of a tautology would be “the runner will win or not win the race”, another would be “A=A”.

There are also those far more common statements that can be verified by observation. “The cat is on the mat” is true or false based on our observation as to whether the cat is on the mat. Hume described these as “synthetic” since the meaning of the statement is not self-evident.

These statements are the only meaningful statements to Hume. They are a posteriori, which means logically true after experience. For example, for the cat to be on the mat we must experience this state of affairs before we know it is true.

Both types of statement, “analytic” and “synthetic” were mutually incompatible to Hume, later philosophers described this as “Hume’s Fork”. Hume’s fork dictated that analytic statements are always a priori, and synthetic statements are always a posteriori.

This all seems like a dry exercise in logic. Pointless, right? But think of these types of statements as being like “pixels” of experience. These logical propositions are the tiny building blocks that make up our knowledge of the world.

The world in all its richness, beauty and variety avails itself to us in logic.

As the twentieth-century philosopher Ludwig Wittgenstein wrote, “The world is the totality of facts, not of things.”

Hume had maintained that the law of causality was synthetic and therefore a posteriori: we were just guessing that events caused other events after the fact of experiencing the events.

We could not know that fire could produce heat before experiencing a fire for certain. To prove it, we would have to set a fire and test the temperature of the air.

If a fire could guarantee heat a priori (before we experience it), it would have to be analytic, and that was not the case. The idea that fire always gives off heat is a “metaphysical” idea that Hume rejected as meaningless.

Hume wrote of metaphysical statements:

“Let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.”

Kant spent twelve years thinking about this problem. Working with the logical system that Hume had developed, he discovered something profound about how we know the world.

Having spent all those years thinking about the objections Hume raised about philosophy and metaphysics, it took Kant only a matter of months to write The Critique of Pure Reason in 1781.

In this book, Kant described a third type of statement which he called “synthetic a priori”. A statement falling into this category would be “a straight line between two points is the shortest.” The statement is not by definition true, but it is universally (always) true in the same way that “all unmarried men are bachelors” is true.

The statement’s truth is not self-evident from the statement itself, it is “synthetic”. But its validity is still prior to our experience of a straight line, it’s “a priori” — logically true before it’s experienced.

In other words — and here is the glorious moment for Kant — we know innately that this statement is true. In finding this new type of statement, Kant crossed Hume’s fork:

Kant found this to be the case for the most fundamental aspects of our knowledge. Mathematical and geometrical propositions were the same. “Five things added to three things give us eight things” or “5+3=8” is a synthetic a priori statement.

Kant maintained that Synthetic a priori propositions are the basis for knowledge, they are the pixels of experience that depend on human intuition. Our experience of the world, Kant maintained, is a mix of experience and rational intuition.

Transcendental Idealism

These experiences, Kant asserted, are woven together through twelve categories of understanding: the way our senses interpret and order the world. These categories include “quality”, “quantity”, “relation” and “modality”.

Think about the statement “five things plus three things gives us eight things”. There is nothing in that statement that is self-evident, our intuition of “quantity” is required to make sense of that statement, as it is when we pick up fruit in the market or count the money in our purse.

Together these categories form the framework of how our minds process experience and produce knowledge. They are not part of our experience — we do not see, feel or hear “quantity” itself, for example — yet we could not have experience without them. Kant described them as predicates of objects in general, not specifically.

In this sense the categories are “transcendent” — they are beyond knowledge insomuch that they actually structure knowledge itself.

Think of it this way: you cannot see your eyes, nor hear your ears because these organs themselves mediate those senses. The categories are like those sense organs — they are aspects of the intellect that make understanding possible.

Kant produced a framework for knowledge that our experience of the world is sense data mediated through our minds. The categories of our intellect exist prior to experience and structure our sense perceptions as we experience the world.

The world outside of our senses cannot be known. “Things-in-themselves” — the source of our sense data that cause our sensations — cannot be accessed outside of our experience.

Kant called his system “Transcendental Idealism”. Causation, space and time are intuitions of our minds. Kant argues that we are cognizant of objects not as they are in themselves, but only the way they appear to us through the categories. “Idealism” is the philosophical belief that reality is inseparable from the mind of the beholder.

Knowledge is not produced solely by experience, nor is it produced solely in the mind. Our knowledge of the world is sense data from the world, structured by our mind.

He believed he had effected a Copernican Revolution in philosophy. He wrote, “I venture to assert that there is not a single metaphysical problem that has not been solved.”

While most philosophers since may disagree, Kant is perhaps the most influential Western philosopher since Aristotle.

Working from his simple logical discovery, he developed enormous ideas around virtually every important question of philosophy that are influential to this day. How should we govern ourselves? (politics), what is beautiful? (aesthetics); what is good? (ethics).