Knowledge is Justified True Belief. What this means is that for you to know something, you have to believe it, it has to be true, and it has to be justified (through deductive reasoning, I think). Now what I mean by true here, is the absolute "truth", not a subjective truth. This in itself can be argued and it is argued against, like you guys are doing right now. But I'm pretty much using Plato's defintion and opinion, so this whole thing is assuming that there is a universal truth (feel free to argue against it, this is philosophy after all). So in other words, "knowledge" cannot be subjective, only beliefs.