Gettier Cases: You Don't Know That

Can we imagine a case where you believe something, you're right, and you've got good reason to believe it - and yet you don't know that thing? We certainly can. Let's say you're a teacher at a high school, and the principal drives a very conspicuous car: a pink Ferrari. You show up to work one morning and see the pink Ferrari in the car park. In the staff room, another teacher asks you whether the principal's at work today.

"Yes," you say. "I saw his car."

As it happens, the principal is at work - but the pink Ferrari in the car park is, by pure chance, not his car but somebody else's. Did you know that the principal was at work?

By any reasonable standard, seeing an identical car to his in the car park would constitute good reason for your belief. And he is at work, after all! But intuitively, we don't want to say that you knew it.

Here's one reason why. If you had been informed that the pink Ferrari was not the principal's car - perhaps the other teacher replies "yes, I saw the car too, but it has a slightly different numberplate" - you would have changed your mind. In order to know something, it seems like there ought to be no true piece of information out there that, if you knew it, would make you decide you were wrong.

This kind of case is called a Gettier case after the first person to formulate one, Edmund Gettier. The general principle is to propose a situation where you have a true belief, but your justification for believing it happens by sheer chance to be wrong. Gettier cases pose serious problems for people who think knowledge is "justified true belief". Can a better definition of knowledge be found? Can the JTB definition of knowledge be altered to accommodate the Gettier cases? There's no consensus in philosophy right now, but I'll outline some competing theories next post.

What We Talk About When We Talk About Knowledge

So we accept that knowledge (or at least the possibility of knowledge) exists. Now what? Now we try to establish what we know about knowledge, starting with its conditions. What are we talking about, precisely? Let's unpack a particular claim of knowledge.

I know the Eiffel Tower is in Paris.

What do I mean when I say this? In other words, what would have to happen for me to be wrong? Well, at the most basic level I appear to be saying that I personally think that the Eiffel Tower is in Paris. If I believed that it was in Berlin, say, then I would be lying when I said I knew it was in Paris. So I am making a claim about what I believe. We can generalize this and say that knowledge requires belief.

I'm not just talking about my belief, though - otherwise I would have said 'believe' instead of 'know'. I'm making a claim about the outside world, in particular about the architecture of Paris. If I believe that the Eiffel Tower is in Paris, but I happen to be wrong, then I don't really know it, do it? The concept of 'wrong knowledge' is incoherent. So we can say that knowledge requires both belief and truth.

Now we are getting somewhere. If I know something, that must mean that I believe it and that it is true. But is this sufficient? Suppose that I have no acquaintance with any facts about Paris, or the Eiffel Tower in general. In fact, I only heard about the Eiffel Tower (which I dimly imagine to be a rifle-thin copy of Saruman's lair from the Lord of the Rings) a few minutes ago, when it came up in conversation. Feeling intellectually outgunned, I jump into the conversation with a wild guess: The Eiffel Tower is in Paris! Do I believe it? Let's say yes, since I'm the kind of person who very quickly develops certainty for no reason. Is it true? Yes, by sheer luck I've picked the right city. But do I actually know that the Eiffel Tower is in Paris?

Of course not. So there must be a third component of knowledge; some reason to think that your true belief is true. I must have some kind of justification for believing that the Eiffel Tower is in Paris. Photos, for instance, or multiple references in books and films. Knowledge, then, requires (at least) three things: that you believe a certain thing, that that belief is correct, and that you have good reason to hold that belief. This is what philosophers call "justified true belief", or JTB, and it was considered a full definition of knowledge for considerably more than a thousand years.

Is it, though? Can you think of a case where the three conditions - justification, truth and belief - are all met, but the belief still does not count as knowledge? If you can deduce it yourself (I certainly couldn't), then you'll find my next post on epistemology trivial.

Discussing Knowledge

To sceptical outsiders, the philosophical investigation of knowledge (epistemology, that is) might seem like an argument over nothing. Can't we simply answer the biggest question - "what is Knowledge" - with a link to an online dictionary or, failing that, a brief explanation of semantics and the nature of context? In other words, 'knowledge' means nothing on its own; its meaning is derived from the sentence in which it sits. You can draw out general senses from this and list them in a dictionary: "being aware of a fact", "familiarity with a concept", "practical skill in a certain area". Capital-k Knowledge has no existence unless it's defined, and the definition is essentially arbitrary; that is to say, almost every possible definition is equally valid.

This is wrong! To see why it's wrong, consider a field of discussion with obvious value, like car mechanics. It's obvious that there's meat there, that there's something of interest to be studied. However, try defining 'car' or 'engine' properly. The same problems that come up when you define 'knowledge' are here as well. Isn't 'car' used in different ways by different people? What counts as an engine? Can you construct an elegant definition that rules out trucks and buses without ruling out actual cars? Ought broken cars and engines count, and if so, where do you draw the line? And so on. Nevertheless, it's still possible to learn how to fix an engine without once touching the tricky philosophical problem of definition.

We drive our knowledge around every day: trivially, whenever we tell other people things. If you make a surprising claim about reality, you're likely to be asked 'how do you know that?' Whether you're a philosopher or not, you need to be able to answer that question - and, in order to do that, you need to have some vague idea of what it means to know anything in the first place.