Wednesday, September 07, 2005

What is knowledge?

[Here's the beginning of the email. I'm cutting off the first paragraph. I know, I know, you're thinking, "Hey, if you cut out the first paragraph, then how can this be the beginning of the email?" You have a point there. Okay, lemme rephrase myself. This is the beginning of most posts of this email. How's that?]

What I want to do is persuade you that logic applies to the real world, that it is necessary, that it is objective, that knowledge is possible, and that language is adequate to convey true information. Sounds pretty ambitious, eh? It is, because technically speaking, I can’t prove logic. (Actually Aristotle has an interesting "proof" of the law of non-contradiction.) To prove something, you have to infer it from things that are known. The laws of logic are rules of inference, so they themselves can’t be inferred without begging the question. Luckily for me, though, I don’t really need to prove logic because you already believe it. Everybody believes in logic, they just don’t realize it. All I need to do, then, is cause your intuition to rise to the surface so that you’ll realize that you already believe in logic.

We know different things in different ways. There are basically four different ways we can know things, and they vary in degree of certainty. But before I discuss how we know what we know, I should give a definition of "knowledge" so you’ll know what I’m talking about. People tend to use a different definition of "knowledge" when they talk about religion or abstract ideas than they do when they use it in their daily lives. When I was in high school, I somehow came to believe that knowledge was not possible. My argument was basically that we only have degrees of belief, but since our belief was never 100% without any degree of doubt, then we don’t have any knowledge. Although I held this idea when thinking abstractly, I was inconsistent in the fact that in my every day life, I still claimed to know some things. If somebody asked me, "Do you know what time it is?" I wouldn’t say, "No, I don’t, but I believe it’s 4 o’clock." Sometimes when talking to my friends, I would catch myself saying, "I know what you mean." In my day to day life, I was using a different definition of knowledge than what I was using when thinking abstractly. The definition I was using turned out to be the way philosophers ordinarily use the word. Knowledge is justified true belief.

That probably needs to be unpacked a little, so I’m going to borrow some analogies from David Sosa, one of my philosophy teachers at UT Austin, to show what I mean. Let’s say David plays the lottery, and he picks his numbers himself. For whatever reason, he becomes convinced that he’s going to win. He doesn’t just hope he’s going to win, he actually believes it. And then lo and behold, he wins! Now, did he know that he was going to win? Probably not, and the reason is because he had no justification for thinking that he was going to win. So it isn’t enough that we believe something which is true to claim that we know it. We must also be justified in holding the belief. David had no real justification for thinking he was going to win. He was just lucky. On the other hand, suppose David is on a jury, and the prosecution presents what appears to be an irrefutable case for the guilt of the man on trial. In that case, David is well-justified in proclaiming the man guilty beyond a reasonable doubt. But what if later DNA evidence frees the man? Can we say that David knew he was guilty? No, and the reason is because you can’t know something that isn’t true. It isn’t enough that your belief is justified, it must also be true. So knowledge is justified true belief.

[After reading this, I noticed I left something out. I said that "Knowledge is justified true belief." I talked about "justified" and about "true," but I didn't talk about "belief." Maybe I left it out because it seemed to banal a point. But it's important. Before you can claim to know something, you have to at least believe it. If a person claims to know that something is true but does not believe it to be true, then he's contradicting himself.]


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