07a. The Meaning of Knowledge. Part 1/2.
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But do you know what it means to know something? We've spent quite a bit of time discussing beliefs and knowledge, but we haven't really been specific about what we mean when we talk about those things. Thankfully, philosophers love a good definition.
They have very specific and lucid ideas in mind when they use terms like know or believe or proposition or justification. And, about ten minutes from now, you too will know what you're really saying when you use those words. But, just because these terms have been defined, doesn't mean that philosophers aren't still arguing over them. Because you know, that's how philosophers do. Their definitions might seem kind of obvious at first, but the more you think about them, the more nuanced they turn out to be.
Like, is having knowledge of something the same thing as being correct? Or, if you believe something to be true, and it is true, does it matter if your belief in it is justified? And can you be right about something without really trying? Answers to these questions and more await you, as well as cats!
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So you've heard this already: Philosophers love a good argument.
But you've figured out by now that philosophers argue in a different way than, like, kindergarten kids, or Internet trolls, or other people who confuse “arguing” with sniping back and forth or just thinking up witty comebacks. Nope.
Philosophers have all kinds of rhetorical devices at their disposal that they can use to advance an idea, or call into question the ideas of their interlocutors. So in order to hold your own in a philosophical debate, you're gonna have to know the difference between two things that sound like exactly the same thing: an assertion, and a proposition. And you'll need to be able to tell whether someone actually knows what they're talking about, or if they just believe what they're saying might be true. For example: The sentence I'm saying right now is an assertion. An assertion is a linguistic act – either spoken or written – that has a truth value. And despite what it might sound like, truth value isn't a measure of how right something is. It's just the state of being either true, or false, or indeterminate. All declarative sentences have truth values. Declarations that assert something about the past or present are either true or false.
And assertions about the future are indeterminate, at least when they're expressed, because no one knows if they're right or not yet. For example, I'm gonna assert that “This cat will pee on my desk before the end of the show.” That assertion has a truth value, but it's indeterminate, because the show's not over yet. We're just gonna have to wait and see. Now, all of this contrasts with other kinds of linguistic acts, like questions, which don't assert anything.
“This is a cat” is an assertion, as opposed to “Is that a cat?,” which is a linguistic act, but not an assertion. But the substance of what you assert has a name, too. The content of your assertion is your proposition. It's the underlying meaning of what you're saying. So even though an assertion itself can change, depending on say, what language it's spoken in, its meaning doesn't change just because its outer packaging does.
Like, “This is a cat” and “Este es un gato,” both assert the same proposition. And a proposition is true if it asserts a claim that corresponds to reality. The proposition when I assert “This is a cat,” is true if the object of the “this” is in fact a cat, and false if it is anything other than a cat. Like, “This is a cat.” It's worth pointing out that attitude counts, too, when you're asserting something.
A speaker's mental state toward the proposition they're making is their propositional attitude. If I say, like, “This is a cat,” but I actually believe it to be a rat and I'm trying to fool you, then philosophers would say that I have a propositional attitude of disbelief. Whereas, if I think I'm speaking truthfully, I have a propositional attitude of belief.
And of course, you're not going to get very far as a philosopher unless you understand the classic definition of belief itself. Based on the lingo you've learned so far today, belief is just when you take a propositional attitude of truth. I believe that this is a cat, if I think it's true – that is, if my attitude is that the assertion corresponds to reality. And even if I'm wrong -- even if there were an aardvark on my desk, or if there weren't a cat on my desk at all, which there isn't anymore -- if I really thought there was a cat on my desk, that would just be my belief. My propositional attitude, in other words, is what determines if I have a belief.
What all this means is that I, like everyone else, can have false beliefs. Simply thinking something doesn't make it correspond to reality, which is what's needed for truth. But of course, the fun of arguing is showing off what you know to other people, or at least producing really clever evidence to support your case. So, this raises the question of what it means to actually know something, in the philosophical sense. The traditional definition of knowledge is that it's a justified true belief.
Note that there are three separate components here. So, I have knowledge that this is a cat if: I first believe i's a cat And also that it is in fact a cat – that is, my belief corresponds to reality and is therefore true. And finally, I can be said to have knowledge about this cat if my belief is justified – meaning, I have some sort of legitimate evidence to support my belief. Now, we've already defined truth and belief.
Justification is simply evidence, or other support, for your belief. If you remember back to episode 2, you'll recall that premises offer justification for conclusions. And justification can come in a variety of forms. Most often, it comes about through testimony – just taking someone's word for it. Not all testimony is strong, or trustworthy, of course. But if it comes from someone who's an expert on the topic in question, you might consider the testimony to be reliable. And the fact is, most of what you know about the world, you learned through testimony.
You took your teachers' word for it when they were teaching you stuff, and the same goes for every book you've ever read and every news report you've ever seen. They're all just forms of testimony, which you accepted as justification for your knowledge, and your beliefs.
