The Noumenal World and the Phenomenal World
Immanuel Kant is one of the most famous philosophers of the Enlightenment. One of his most celebrated works is the Critique of Pure Reason where he explains his view of the world and how we come to know things about it. In order to really understand Kant you need to understand what he was arguing against and, to put it simply, he was arguing against skeptics who said that when you perceive things you are never really perceiving the actual thing itself but instead you are only perceiving the ideas in your head of what that thing is like. As such, the skeptics argue, because there is sort of a gap between the world and the image inside your head, that image of what the world is like could be completely different to what the world is really like. Kant disliked this and wanted to prove that although we do not have direct access to the world as it really is, the ideas in our head are reliably based on what the world is really like outside.
In the simplest sense, Kant says that there are two different worlds. The first world is called the noumenal world. It is the world of things outside us, the world of things as they really are, the world of trees, dogs, cars, houses and fluff that are really real. However, Kant says, our minds are created in such a way that we cannot comprehend this world as it really is. Instead what we perceive is like an altered version of this world which Kant called the phenomenal world. The phenomenal world is the world that we perceive or to put it another way, the view we have of the world that is inside our heads. Diagrammatically, it might look a bit like this:
So why doesnít information come cleanly into our heads from out there in the real world? Why do things get messed up on the way in? Kantís answer is that a number of axioms, assumptions or rules (which he also called schema) are hard wired into our minds and they interact with the real (noumenal) world to help create the phenomenal world that exists inside our heads. In a sense these axioms or rules are like a filter between our minds and the real world, a bit like a man who is wearing sunglasses. The sunglasses are like the schema and they alter the way that the world really looks to create the world that exists inside our heads, as such the man with the sunglasses on will see things as blacker or darker than they really are.
The important point is that our perceptions of the world donít just come out of nowhere, they are caused by the world outside and so we are perceiving a world that really exists, but what that world looks like to us is a bit different to what that world is really like. The problem, however, is that while you can take off the sunglasses to see how bright things really are, you can never take the rules, axioms, assumptions or schema out of your mind in order to find out what the world outside of your head is really like. So Kant creates an unbridgeable gap between the world out there as it really is, the noumenal world, and the world as we perceive it, the phenomenal world inside our heads.
In his Critique of Pure Reason Kant lists the 12 different axioms, assumptions or schema that he thinks make up the filter between our minds and reality. These filters arenít like sieves that remove bits and pieces of information, instead they are like concepts that we use to organise the information we receive from the world, concepts that we just canít help believing in. Some of these concepts are that there is such a thing as time, such a thing as space and such a thing as causality. We can assume, therefore, that the real world is timeless, spaceless and has no causal links in it Ö but it is impossible for us to actually visualise or understand this world because the concepts of time and space are such an integral part of the way we think that we just canít imagine what a world without them would be like.
In a sense, although the examples above concentrated on seeing, this is actually a bit misleading. Kant isnít really trying to make a point about the unreliability of perception, he is actually getting at something a bit deeper. Kant is essentially saying not that our perceptions are wrong, but that the way reason acts on our perceptions alters them irrevocably and thus it is our reason here that is acting as the filter and altering the way we view the world. Thatís why his axioms and assumptions are more related to concepts of reason (e.g. causality) than they are to elements of perception (e.g. blue, hot, sweet, etc)
So why is this relevant to TOK? Well, TOK is a subject that concerns itself with the pursuit of knowledge and whether we are justified in claiming to know what we think we know. Kant, it seems, gives us access to a real world of truths, facts and certainties but doesnít allow us to ever know what those truths really are.