Introduction

What is Epistemology?

Arguments That You Don't Have Very Much Knowledge

There are a number of philosophical arguments that purport to show that you don't have any knowledge--or at any rate, that you don't have very much knowledge.

1. One of these arguments goes as follows: Knowledge requires absolute certainty. And for most propositions, you can't be absolutely certain that they're true. You might be wrong about them. After all, sometimes people turn out to be wrong even about things they were completely confident of. So for all propositions of that sort, since you can't be absolutely certain that they're true, you can't know that they are true.

2. A second argument that you don't have very much knowledge goes as follows: Consider the possibility that none of the things you perceive right now are real. It's all an illusion. Maybe it's just a dream, or maybe you're a brain in a vat, being force-fed experiences through some neural hook-up, like the characters in The Matrix. If you were just dreaming all this, or if you were a brain in a vat, then everything would seem the same. So how can you know that it's not a dream? How can you tell whether the world you see around you is real or just an illusion?

   A skeptic is someone who doubts whether we have knowledge of a certain sort. For instance, a skeptic about the external world is someone who doubts whether we have knowledge of the external world. That's the kind of skeptical challenge posed in The Matrix, and which we will be focusing on in this class.

   There are also skeptical challenges to your knowledge of other minds, your knowledge of the future, of the past, of right and wrong, knowledge on the basis of other people's testimony, knowledge of unobserved scientific phenomena, knowledge of what your own words mean, knowledge of mathematical facts, and more.

3. Here's a third argument that you don't have very much knowledge. Suppose you have a lottery ticket, and the chances of winning are only 1 in 15 million. The odds that your ticket will lose are very high. But it doesn't seem like you know that your ticket will lose. After all, if you did know that (e.g., if you knew that the lottery was fixed and that some other ticket was already selected to be the winner), then why would you buy a ticket? Plus, if you did know that your ticket will lose, because the odds of its losing are so high, then by parity of reasoning you should be able to know of every losing ticket that it will lose. But then you'd be able to say which ticket would win! And of course you can't do that. So it seems wrong to say that you know your ticket will lose.

   Notice that this isn't really affected by how high the odds are that your ticket will lose. Even if the odds that you will lose are 15 billion to 1, it still seems wrong to say that you know your ticket will lose. As long as there's any chance at all that your ticket will win--no matter how small--then it doesn't seem like you can know you won't win.

   Now, the argument continues, the same is also true for our ordinary beliefs, about matters other than lotteries. As long as there's any chance at all that those beliefs are mistaken (or any chance at all that we're brains in vats...) then it doesn't seem like we can know those beliefs to be true.

In this course, we will spend a lot of time thinking about these arguments, especially the second argument.

To begin with, though, let's first try to get a bit clearer about the very notion of knowledge.

Knowledge and Justification

So to know P requires more than just believing P, and happening to be right. In addition, it seems like you have to have a REASON to believe P, or EVIDENCE in favor of P, or some JUSTIFICATION for believing P. (We will treat all these notions as synonymous.)

At the start of class, I said that epistemology is the study of the questions: What is knowledge? and: Can we have any? Because of the observation we just made, epistemology is also very much concerned with the questions: What is it reasonable for us to believe? and: What is the connection between reasonable or justified belief and knowledge?

As we'll see this term, it is controversial just what "justification" or "reasonable belief" amounts to, and what the connections are between justification and knowledge.

Let's make one distinction right now, to avoid trouble later on.

• One question is whether you have practical justification for believing something. Some beliefs are particularly useful to have, or have a good "pay-off." For instance, Pascal argued that it's rational to believe in God because the expected "pay-off" of having that belief (going to Heaven) is so high. William James discussed a case where a climber gets stuck in the Alps and has to jump across a crevasse. Suppose that it's more likely that the climber will succeed if he believes that he will; and suppose the climber knows this. Then, James argues, what it's rational for the climber to do is to form the belief that he will succeed. Having this belief will make his life better off. Pascal and James are arguing that these beliefs are ones we have practical justification for accepting.

• Another question about justification has to do with whether your beliefs are supported by good evidence, which makes them likely to be true. When your beliefs are supported in this way, we say that they are epistemically justified. Pascal's and James's arguments do not show that belief in God or the climber's belief that he can successfully jump the crevasse are epistemically justified. Those arguments don't do anything to show that those beliefs are likely to be true. (Although the climber is more likely to jump the crevasse if he believes he can, that does not mean that he is very likely to do so. Perhaps believing that he will succeed only raises his chances from 5% to 10%.)

The connections between epistemic justification and practical justification are philosophically very interesting, and these are questions that epistemologists sometimes investigate. But most often, when epistemologists talk about "justification," they mean to be talking about epistemic justification. And that is the notion we will be focusing on in this class. I said before that it seems like knowing that P is true requires you to have justification for believing P. What I meant was: it seems like it requires you to have epistemic justification for believing P. It seems like you can only know that P if your belief that P is supported by good evidence, which makes it likely to be true. (Of course, as I said, the connections between knowledge and justification are controversial. We will be discussing those controversies as the term progresses.)

So at first glance, even if Pascal's belief in God and the mountain climber's belief that he can jump the crevasse are rational in one sense (they are better off, or practically justified in having those beliefs), that does nothing to show that these beliefs count as knowledge. Pascal's argument does not enable him to know that God exists. The mountain climber's reasoning does not enable him to know that he can successfully jump the crevasse.

Knowledge and Truth

Notions like "predicting" and "believing" and "reporting," on the other hand, are not factive notions. If I predict that P is the case, it does not follow that P really is the case.

Now, how about the notion of knowledge? "Knowing that P" seems to be another example of a factive notion. It doesn't make any sense to say:

In fact Sue is guilty of stealing the car, but the jury knows that she is innocent.

If you said that, it would sound like you were contradicting yourself. It'd be okay to say:

In fact Sue is guilty of stealing the car, but the jury thinks it knows that she is innocent.

But it seems like, for the jury to really know that Sue is innocent, it has to be the case that Sue is innocent. You can't know things which are false. You can only seem to know them, or falsely think that you know them.

So this is one important fact about knowledge. If you know that P, it follows that P is true.

Nonetheless, there is an important difference between what's true, on the one hand, and what we know or can know to be the case, on the other. Sometimes I will use the adjective "objective" to emphasize this. I will talk about things being objectively true, or objectively false. What I mean by that is that those things are true or false independently of what anybody believes or knows about them. For instance, the mountains in Tibet don't care very much about whether we exist or about what we know. They would still have the heights they do no matter what we believed about them. So the claim that Mt. Everest rises 3600 m. above the plateau of Tibet is a good example of a claim that's objectively true. It's true independently of what any of us know or believe or have evidence for believing.

As soon as you start talking about "objective truth," that starts to make some people uncomfortable. They'll say: "Oh, so you think you have some superior perspective to everybody else?" No, just because a person talks about objective truth, it doesn't follow that he thinks he has a superior perspective. So long as it makes sense for Mt. Everest to have a certain height, independently of what people know or believe about its height, then it's legitimate for us to talk about objective truth here. We needn't also claim that we know what Mt. Everest's height is, or that we are better placed to know what Mt. Everest's height is than other people are. Those are further claims, and they would require further argument and defense.

Another thing people sometimes say, when you start talking about "truth," is: "Well, that may be true for you but it's not true for me." What do they mean by this? Sometimes it seems okay to talk about something's being true for one person but not for another person. For instance, if I say, "Coffee tastes good," you might respond, "That may be true for you but it's not true for me." In other words, coffee tastes good to me but it doesn't taste good to you. That doesn't sound so bad. But what could it mean to say, "It may be true for you that Mt. Everest rises 3600 m. above the plateau of Tibet, but it's not true for me"?

Perhaps the people who say this just mean, "You may believe that Mt. Everest is 3600 m. tall, but I don't believe it." If so, then they've certainly chosen a misleading and obscure way to express themselves.

But let's suppose the people who say "That may be true for you, but it's not true for me" want us to understand them literally. They really do think that claims about Mt. Everest's height are true for some people but false for others. What could they possibly mean by that?

Perhaps they've studied special relativity in their physics class and they're saying it because they think they're travelling at a different velocity than I am. But let's ignore special relativity for the time being. It doesn't change the basic point we're discussing here; it just forces us to discuss a more complicated example. To keep things simple, let's just take it for granted that we're all travelling at the same velocity.

On the view we're considering, Mt. Everest has two different heights. One is its height for me, and the other is its height for you. And if I change my mind about what Mt. Everest's height is, then its height (its height for me) will change. Who would have thought I had so much power! And I guess if none of us existed anymore, then Mt. Everest would have no height.

Look, that is a possible view. Some philosophers have argued for it. But that doesn't mean it's very plausible, or that it's worth taking very seriously. Philosophers have also argued, at various times, for the following views:

• Only one thing exists, and it has no parts.
• I am the only thing which exists.
• Time does not exist. Nothing ever changes.
• No people exist, including me. I do not exist, and you do not exist.
• Numbers do not exist.
• Numbers do exist, in fact they are the only things which exist.

and all sorts of other crazy views. When you come across crazy views like these, I hope you will have your guard up. It's OK to discuss and investigate what the arguments for these crazy views might be. Often that can be philosophically illuminating. But I hope that you will want to see a really damn good argument for a crazy view like these, before you'll be tempted to accept it. (And if you think you have a really good argument for a view like these, I hope that you'll scrutinize it especially closely.)

So, too, some philosophers have argued for views that deny there are any objective truths. They deny that what's true is independent of what we know or can know to be true. We will discuss these views in a few classes (when we read Bouwsma's article, and some passages from van Inwagen's book--you can look ahead at the van Inwagen, if you like...) But for now, let's work with the assumption that there is a difference between what's true and what anyone believes or knows to be true. There is a fact of the matter about what Mt. Everest's height is, independently of what you or I or anybody else believes about its height. (Physics junkies can substitute: a fact of the matter about what Mt. Everest's height is, relative to such-and-such a reference frame, independently of what anybody believes its height is, relative to that reference frame.)

Perhaps philosophical argument will convince us that this natural view is incorrect. But that will be our starting point.

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