Knowledge is commonly regarded as true belief, but it’s actually belief with certainty.
Knowledge is a mindstate, and we are aware of our own mindstates. If whether we know something depends on things outside our mindstate, then we can never know whether we know something. Yes, you can come to more or less accurate knowledge by means of evidence, reason and other faculties, but knowing something is already believing it to be true, so if it has to be true objectively too then there must always be doubt, because the justifications for believing it’s true have *already* been made by virtue of it being knowledge. So the doubt that it may not be knowledge must exist *outside* of the justification for its being true. That means it must always be there, thus we can never know if we know something, thus we can never know of our own mindstate.
Knowledge must be a mindstate because we assess whether we know something, in order to report “yes, I know that” or “no, I don’t know that” by looking inward, in a similar way to how we assess whether we believe something. One could argue that what we’re assessing is whether we *believe* we know something, but to propose that we never actually know what we know or don’t know would be an offense to common sense and absurd. Common sense isn’t always right, but the meaning of a word, such as the word ‘to know’, is defined by common usage.
People say that doubt is the lack of certainty, because they imagine that certainty is the absolute elimination of all other possibilities, so if any of those other possibilities linger, then there’s doubt. But that’s not how it is. We can never have absolute knowledge anyway, and certainty is a willful choice. Certainty is a state of mind, and doubt is the entertainment of some particular other possibility. Doubt is not the absence of certainty, certainty is the absence of doubt. Yes, certainty as the absence of doubt is compatible with the view of certainty as the absolute elimination of all other possibilities, but it is not the case that doubt is the absence of certainty, any more than heat is the the absence of cold. Yes, you can be certain and wrong.
You may want to argue that certainty is not only a state of mind, but that it does or can refer to objective truth. However, certainty applies to possibilities, it’s assigning a 100% probability to one possibility and 0% to all others. That’s the intention of the word–otherwise you wouldn’t call it certainty, you’d call it truth. In objective reality, there is no context for this because there are no other possibilities other than what exists. If anything is certain outside of mental attitudes, then everything is certain, because whatever is, is with 100% probability, and that would, of course, make the word useless. Neither is certainty a relationship between belief and reality, as some people claim truth is, because that would lead to the idea that we can never be sure of when we’re certain of something (in the sense that there would always be a reasonable doubt), which again defies common sense.
—excerpt of a conversation in IRC—
<beaky> if anything i feel its made me dumber 😀 i thought knowledge was justified true belief, but then gettier problems
<beaky> so i dont really have knowledge
<inhahe_> personally i think knowledge is essentially a state of mind. though it’s kind of used simultaneously to mean belief that happens to be true. i think it has two meanings and the two meanings are commonly conflated
<inhahe_> hence the confusion over teh definition of knowledge