Fall 2002

Theory of Knowledge Introduction

What is Epistemology?

At a first pass, Epistemology is the study of the questions: "What is knowledge?" And "Do I have any?"

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: 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 the past, the future, mathematical facts, and unobserved scientific phenomena; challenges to your knowledge that other people have minds, and to whether you can ever rely on their testimony; and more. There are even challenges to whether you can know what your own words mean.

2. Here's another 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 should 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 it doesn't really matter how good 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 true also for our ordinary beliefs, that have nothing to do with lotteries. 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 those propositions, since you can't be absolutely certain that they're true, you can't know that they are true.

   For instance, it looks and feels to me as if I have hands; so I believe that I have hands. Of course there's some chance that I'm making a mistake. Maybe I'm just hallucinating hands, or maybe I'm a handless brain plugged into the Matrix. I think those things are very unlikely, but I'm willing to say there's some small chance that they're true. So according to the reasoning we've been considering, it follows that I can't really know that I have hands.

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

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