In my previous post I mentioned Immanuel Kant but didn’t get around to discussing him. Over a period of twelve years, Kant, a German philosopher, developed the ideas that he would commit to writing in the now-famous work, Critique of Pure Reason (to be followed by two other “Critiques“). In part, what motivated Kant was his reaction against David Hume’s skepticism. Obviously his writings were extensive, but this post will focus on one aspect of his ideas that seems to me to be fairly straightforward.According to Kant, there is a distinction between a thing in itself and a thing as we perceive it with our senses. As he put it, “I have no knowledge of myself as I am, but merely as I appear to myself.” The real world, the things in themselves or noumena, are perceived through our senses and that perception is a phenomenon that is distinct from the thing itself. In other words, “Though the noumenal holds the contents of the intelligible world, Kant claimed that man’s speculative reason can only know phenomena and can never penetrate to the noumenon.”
The problem for Kant’s Critique of Pure Reason is very similar to the problem that we earlier identified with Hume. Kant claims he knows something about the real world, but the thing he claims to know is that human beings cannot know anything about the real world. As Geisler/Turek put it “In effect, Kant says the truth about the real world is that there are no truths about the real world.
The law of noncontradiction rears its head again. Kant cannot claim both that the real world cannot be known and that it can be known. If it’s impossible to penetrate to the thing itself with our senses, then Kant has no basis for claiming that the thing itself is truly different from the thing as it is impressed on us by our senses. If the phenomenal and the noumenal are indistinguishable, then they must be just as indistinguishable for Kant as they are for anyone else.