Immanuel Kant (1724–1804) was the first of the German Idealists. His most well-known work is Critique of Pure Reason. In this book, Kant sets forth his philosophy, called critical philosophy.

What Lies Beyond

Kant was interested in metaphysics, which is what lies beyond our ability to perceive. We only get tantalizing flashes of the metaphysical world. According to Kant, we can never really grasp the true nature of the material world. Things such as the soul or the existence of God were unknowable and unprovable. They were matters of faith. Kant was influenced by the philosopher David Hume and by the scientist Sir Isaac Newton, even though the former said that nothing is real and we cannot grasp it anyway, and the other “proved” the laws of gravity and other scientific “realities.”

Science Versus Faith

Kant, who had more or less been a follower of Liebniz, read a book by David Hume in middle age and claimed to have awakened from a “dogmatic slumber.” Hume's view that there were no certainties in life and that we were all merely a mishmash of sensory impressions rattled old Kant, a fusspot old bachelor and apparently a rigid creature of routine. He sought to make sense of it all and resolve the seeming conflict between science and faith, an age-old philosophical dilemma.

One thing that even the most skeptical philosopher could agree on is that two plus two equals four. For the most part, mathematics was regarded a constant in a chaotic universe. Kant sought to do nothing less than reconcile the conflicting philosophies of rationalism and empiricism.

In his book Critique of Pure Reason, Kant defined two types of judgments, the analytic and the synthetic. The analytic judgment is one where the truth can be determined within itself; that is, the definitions of the words within the statement of truth affirm the truth. The famous example of this is “All black houses are houses.” Of course, a black house is a house. An example of a synthetic truth is simply “The house is black.” This needs to be determined by the action of looking at the house in question to see if it is indeed black.

Two other ways of judgments are what Kant called a priori and a posteriori. These are simply the Latin words for “before” and “after.” “All black houses are houses is an a priori judgment — you do not have to see the houses to know this. “The house is black” is an a posteriori judgment — you have to see the house to determine its color.

Two more terms in this Kantian point-counterpoint are Transcendental and Empirical. Transcendental would be a priori knowledge — it is a given, and you just know it to be true. Empirical is a posteriori knowledge — you need to observe it to ascertain its truthfulness.

Following this logically, there would be one column of analytic, a priori, and transcendental, and another column of synthetic, a posteriori, and empirical. Kant sought to take one from Column A and one from Column B and see what he came up with. Through mixing and matching, Kant found that some combinations were illogical, but he liked the notion of the synthetic a priori. This concept would be nothing less than a Universal Truth arrived at through a scientific method.

Reality

Kant proposed that reality is not an ordered universe waiting to be perceived by the human mind. Rather, the human mind takes the chaos out there and orders and structures it into the reality that we perceive. Time and space as we understand them are not concepts external to us; they are intrinsic mechanisms that enable us to make sense of reality. We create our own reality not out of mental illness or egotism; it is simply the way of things.

Reality, if we were to see it without the filter of our own mind and perception, would be something like a preschooler's scribbling in crayon. In other words, it's a nebulous jumble in which we would be unable to maneuver, and that would probably drive us mad.

Kant speculated on the nature of the noumenal, or metaphysical, world. He looked at the otherworldly realms from an optimistic standpoint. Kant believed we had regular intuitive hints to the nature of the noumenal world. The feeling of awe on a starry night, a spiritual sense of oneness with the cosmos is one such clue. Kant believed that there was a God, a universal justice, and immortality to be found on the “other side.”

As a result, Kant posited that humankind does not receive all his knowledge from sensory experience alone, as the Empiricists claimed. Nor does he comprehend things through reason alone, as the Rationalists firmly maintained. This was a revolutionary thinking in the history of philosophy, and Kant influenced almost every philosopher that followed. His immediate heirs, the other German Idealists, although deeply affected by Kantian thought, revised, modified, and disagreed with him.