How do I know what is true and what is false? This is a surprisingly deep question, and surprisingly few people ever think much about it. Or then again, perhaps it isn't surprising. Whether we are aware of it or not we all have mental machinery humming along that helps us make the countless choices we need to make. Most of us instinctually recognize that messing with this machinery might cause a person's life to break down. Indeed, I have seen it happen -- people can literally think themselves into craziness. But on the other hand not understanding how we make decisions leaves us helpless to our own machinery. Your unconscious machinery might have problems, and sometimes, like in the case of the young woman choosing to live or die this makes a great deal of difference. If we want to lead a deep, rich fulfilling life it is necessary to make sure that our underlying assumptions (our mechanism) is sound. And one of the key assumptions that we need to examine is how we sort data into knowledge - how do we decide if we believe something is true or not?
Think about what is going on when you argue with someone. Presumably, we argue with people to get them to see our point of view, and hopefully convert them. Amazingly, it occasionally works, but why? How are they persuaded to change their mind? It turns out we all have an innate sense of logic. This is the basis for our reasoning. You can make a logical argument to me, and if I happen to be in a rational mood I might recognize the truth of your words.
You find this truth by turning inward and thinking about it. Some rational part of us just recognizes truth. This is a very powerful faculty – it is how we conquered the planet. Possibly the purest expression of pure reason is mathematics. That discipline is based on proofs. For convenience most of us in school just skipped over the proofs and went straight to using the results, but, in principle, learning Mathematics is a process of self-discovery. Mathematicians don't believe in the proofs because someone else told them to. Instead, they believe them because they have stepped through the proof in their own head, and gone over it and over it until they find that they recognize the truth in it. When we study math proofs we go through an accelerated, significantly cleaned up re-creation of the history of mathematics. That is, we are re-creating the same mental discovery process inside ourselves as the original mathematicians - no wonder it is so hard! But the beauty of studying math this way is that you don’t have to take someone else’s word for it – you find the truth inside yourself.
In the same way, philosophers like Kant try to be as rigorous as possible in their arguments. That is why philosophy books are usually so hard to read – they are meant to mimic mathematical proofs. But the beauty of this approach is that you verify the truth of what the philosopher has to say in your own head. Just like working out a mathematical proof, you work (and work) with the philosopher’s ideas constantly checking your internal sense of Truth to see if you have a match. In that essay we read of his, Kant was trying to prove that all moral decisions could be based on purely rational thought alone. His hope was that all moral decisions could be approached using the same beautiful internal machinery that we use for math proofs. There would be no need to rely on arbitrary religious authorities; the truth would be self apparent to anyone willing to think about it deeply and logically enough.
I believed this. In some ways I still do. The beauty and elegance of this approach is deeply appealing to my rational side. We all have a powerful sense of logic that can help guide us. It is imperative that we learn to use it – too few people seem to know how to think deeply. But it is not our only source of truth. We have other faculties we can turn to in addition to pure reason. Rationalists can get confused about this. Science is partly to blame for this. It has had incredible success in explaining the world. The problem is, we have almost had too much success. The tendency is to try and explain everything through scientific, rational methods. Many people take the position that they won't believe anything that cannot be scientifically or logically proven. I think for many this has lead to arrogance and a certain mental laziness. What we forget is that as powerful and wonderful as human reason is, it is just one source of truth. There are many questions in our life where it is inappropriate to think about just rationally. The young woman deciding on whether to commit suicide or not is a dramatic example, but there are many others.