on Nov 3rd, 2007An introduction to Knowledge Theory
In our day to day lives we claim knowledge of many things. You know what horses raced last weekend, you know what horses are racing next weekend and sometimes you might even say you know which horse is going to win next weekend. Have you ever said you knew something and later found out that you were wrong? Would you in hindsight use the word know when you later found out you were wrong? If you say no, then we have begun to form a definition of what knowledge is.
The three race related items I listed above are to begin with beliefs. You can not know something without believing it. We have also pointed out that what you know has to be true, you can’t know something false. You can believe something false but you can not know it. So does knowledge mean a true belief? When we ask that in a philosophical sense we are asking if the parts of that definition are both necessary and sufficient. When defining knowledge, say something is necessary is to say that you can not have knowledge without that part. So in our definition so far belief is necessary because we said you can not know something that you do not believe and truth is also necessary because you can not know something that is not true. Are belief and truth though sufficient to define knowledge. That is to say is every example of a true belief knowledge or is there a third criteria for knowledge (or even a fourth and fifth).
The problem with true belief is that I can believe that my horse is going to win next week and it might even be true that my horse is going to win next week but do I “know” that my horse is going to win next week? Most of us I would guess would say no, I don’t know the outcome of a race before it happens. So belief and truth are both necessary conditions of knowledge but they do not appear to be sufficient conditions of knowledge. So what is missing from my definition of knowledge, what third (or fourth and fifth) thing can I add to get a definition of knowledge? The traditional answer has been justification. I have to have justification for why I believe my horse is going to win and I have to be correct my horse is going to win (and of course believe that my horse is going to win) before we can say that I know my horse is going to win. Philosophers have traditionally called this definition of knowledge “Justified True Belief” (K = JTB).
I might say I am justified in believing that my horse is going to win because I know somebody is going to drug all the other horses next weekend. That looks like justification to me, and if it is true that my horse wins it looks like I could say that I know my horse is going to win next weekend.
Justified True Belief was the dominate theory of and definition of knowledge from the time Plato lived until 1963. That is a pretty good run for a theory, even in philosophy. If you stay tuned in, tomorrow I will tell you what happened in 1963 that changed over 2000 years of epistemology and hopefully touch on why knowledge theory is important to us.