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Oh Yeah, What Do YOU Know?

Spotted: Nick Cage at M.S.G. Panda

Sitting in the food court at the local mall, you see Nicolas Cage in line at M.S.G. Panda, ordering a plate of sweet and sour pork. You get excited about spotting a celebrity and tell your friend. He takes a look, smacks you in the arm and exclaims, That's not Nicolas Cage! It's Dr. Van Engan.¹ You respond, No it's not! It's Nicolas Cage. I know it is, to which your friend replies, Well, if it's Dr. Van Engan, then it's not Nicolas Cage. So, how can you be so sure it's not Dr. Van Engan?

Thinking about the fact that you really have a poor view of the guy in line — you're not that close and, besides, you've seen a lot more of his back than his face — you admit that you don't know it's not Dr. Van Engan. But, still, you continue to insist that it's Nicolas Cage. I know it's Nicolas Cage, you tell your friend.

It really is Nicolas Cage, so your belief is true. But can you really say you know it's Nicolas Cage? You admit that you don't know it's not Dr. Van Engan, and you realize that, if it is Dr. Van Engan, then it's not Nicolas Cage. So how can you claim to know that it's Nicolas Cage? Since you don't know it's not Dr. Van Engan, isn't your claim to know that it's Nicolas Cage obviously false?

Closure, and Not the Personal Kind Either

This story exhibits a principle you probably believe, even if you've never thought about it. It's called the closure principle, and it should be obvious that it's true.² The closure principle is important for at least the following reason: If it were false, deductive reasoning would be completely irrelevant to knowledge.

Closure
If Jones knows A, and Jones knows "A" entails "B," then Jones knows B. However, if Jones knows "A" entails "B" but doesn't know B, then Jones doesn't know A, either.³

If you agree that, in the above scenario, "you" really don't know that it's Nicolas Cage in line at M.S.G. Panda, it's probably because you agree with the closure principle. The Nick Cage story exemplifies the closure principle. Here are a few more examples of the closure principle in action:

If you know London is in England and you know "London is in England" entails "London is not in Thailand," then you know London isn't in Thailand.

If Eddy knows "Spiro Agnew is a man" entails "Agnew is a mammal," but Eddy doesn't know that Agnew is a mammal, then Eddy doesn't know that Agnew is a man.

If Screech knows Zack Morris is going steady with Kelly Kapowski, and Screech knows "Zack's going steady with Kelly" entails "A.C. Slater isn't going steady with Kelly," then Screech knows that A.C. isn't going steady with Kelly.⁴

Does Bo Really Know Football?

The closure principle is kinda like the Pythagorean theorem. It's one of those things that, upon a little reflection, seem undeniably true. But the closure principle can be wielded by the skeptic to argue that, contrary to what you and I and almost everybody on earth thinks, nobody (other than God) really knows anything.

Here's how the skeptic might wield the closure principle against the belief that we know things.

Betty and Bo are leaving the theater where they just finished watching The Matrix. On the drive home, Betty announces that nobody knows anything. Bo gives Betty an incredulous look and claims to know that he used to play football. Betty responds to Bo's incredulity as follows:

"Think about it, Bo. How do you know you're not trapped in the Matrix, being deceived to think you used to play football? How do you know all of the experiences you're having right now aren't hallucinations caused by the Matrix? And how do you know your memories aren't a product of the Matrix too? The Matrix could easily make you think you used to play football. Because the memories you're having right now are perfectly compatible with the memories you could have if you were trapped in the Matrix, you really have no way of knowing that your memories aren't a product of the Matrix.

The same goes for your present experiences. Because they could all be products of the Matrix, you have no way of knowing that they aren't products of the Matrix. If I claim that you are in the Matrix, there's no way for you to disprove me. So you don't really know that you're not in the Matrix. But if you don't know you're not in the Matrix, and if the Matrix could deceive you into thinking that you used to play football, then you really don't know that you used to play football."

Here's the gist of the argument Betty just presented Bo.

(1) If Bo knows he used to play football, and Bo knows "I used to play football" entails "I am not trapped in the Matrix being deceived to think I used to play football," then Bo knows he's not in the Matrix being deceived to think he used to play football.

(2) Bo does not know he's not in the Matrix being deceived to think he used to play football.

Therefore,

(3) Bo doesn't know he used to play football.

So, What Do You Know?

Betty's argument is obviously valid. If (1) and (2) are true, then so is (3).

(1) is just an instance of the closure principle, so denying (1) isn't a very appealing option. But (2) seems true, too. After all, Bo can't point to a single memory or experience he wouldn't be having if he were in the Matrix. So it seems like Bo doesn't really know he used to play football

The problem is, Bo's situation puts you, the reader, in a tough spot too.

Take, for example, the belief that you are reading a TrueU article right now. Consider the claim that, in reality, you're trapped in the Matrix, being deceived to think you're reading a TrueU article. How would you respond to this claim? Can you do any better than Bo?

Granted, it doesn't seem like you're trapped in the Matrix right now. But this, of course, is beside the point. If you were trapped in the Matrix, it would seem like you weren't trapped in the Matrix, since the Matrix is specially designed to deceive you into thinking you're not in the Matrix.

How, then, is your belief that you're reading a TrueU article any different than your belief (above) that you see Nicolas Cage standing in line at M.S.G. Panda?

You know that, if the guy is line is really Dr. Van Engan then the guy in line isn't Nicolas Cage. You also admit you can't rule out the possibility that it's Dr. Van Engan. But if you can't rule out the possibility that it's Dr. Van Engan, then how on earth can you continue to claim to know it's Nick Cage? Your claim to know that it's Nick Cage seems obviously false.

But you also know that, if the Matrix is deceiving you into believing that you're reading a TrueU article, then you aren't really reading a TrueU article. And you see that you can't rule out the possibility that you are in the Matrix. (After all, you can't point to a single experience you wouldn't be having if you were in the Matrix.) So, how on earth can you claim to know that you're reading a TrueU article? And if you can't claim to know this sort of thing, then what can you claim to know? After all, what could you possibly have more evidence for than that, right now, you're reading a TrueU article?

Because you can't rule out the possibility that you are a prisoner of the Matrix, being deceived to think you're living the life you think you're living, it seems that you can't really know anything.

Reader, Read On!

OK, so, I'm actually not very impressed by the above argument, and I'm happy to concede that you, the reader, actually know a lot. (And we've never even met!) But this argument does present us with a puzzle, doesn't it? And not just a trivial puzzle, either. If we can't know anything, then we can't, for example, know that God exists. How, then, can we be justified in telling people that they ought to believe in God?

C O F F E E  S H O P

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If we can't know God really exists, are we justified in telling people to believe in Him?

Join the discussion!

I'm going to respond to this argument in my next article. As it turns out, the closure principle can be wielded against the skeptic more effectively than it can be wielded by the skeptic. But I'll tell you all about that in a month. Till then, happy philosophizing.