Global Skepticism

We have looked at several arguments for external world skepticism—the view that we cannot know anything about the external, mind-independent world.

Here, we will look at two arguments for global skepticism—the view that we cannot know ANYTHING AT ALL! [Note that some form of these actually date at least back to Sextus Empiricus (~200 AD), who attributes them to Pyrrho of Ellis (~300 BC).]

1. Infinite Regress: (Excellent video here.) Imagine that my friend tells me, “Chad, I know your future. You will die tomorrow.” I will definitely ask, how? How do you know that? What reason do you have for believing this? But, imagine that they reply, “No reason. I just started talking and that’s what came out.” I would definitely conclude that they did NOT actually know that I was going to die, right? (and probably also that they are not a very good friend)

But, what if, instead, they DID supply a reason? “How do I know that you will die? Because I know that an anvil is going to fall on your head at noon.” Still, I will press: How do you know THAT? NOW what is your reason? “No reason,” they reply. “I just said that bit about the anvil on a whim.” Again, I will conclude that they did not really know that I was going to die.

But, even if they DO supply a reason, if they do not have any reason for believing in THAT piece of the evidence, I will still conclude that they did not have knowledge; and so on. In short, it seems like, in order to have knowledge, there will need to be an infinite regress of reasons! But, an infinite regress of reasons is impossible. Therefore, if justification requires this sort of structure, then knowledge is impossible.

Logically, there are two other possible structures that justification could have, which do NOT involve an infinite regress:

Circular reasoning: For instance, imagine that my friend says:

(1) “I know that you will die tomorrow at noon.” How do you know? (2) “Because an anvil will fall on you.” How do you know? (3) “Because you will be walking right underneath it at noon, right when the rope snaps.” How do you know? (1) “Because that’s when you will die tomorrow, at noon.” And so on.

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Here, my friend is reasoning in a tight circle. But, you can surely see that they still have not supplied any real justification for their belief! Claim (1), which needs to be justified, ends up serving as its own justification! Some other examples of circular reasoning:

One link: A because A … I like pizza. Why? Because I like it. …

Two links: A because B because A … I need to eat. Why? Because I’m hungry. Why? Because I need to eat. …

The original example above had three links: A because B because C because A …

As you can probably guess, adding more links in the circle will not help. A statement can never serve as evidence for ITSELF no matter HOW many steps we add in between. In short, circular reasoning cannot give rise to knowledge.

Foundationalism: Perhaps my friend could eventually arrive at some bedrock assertion which is NOT supported by a further reason, or evidence, but is somehow still justified?

But, it is difficult to see how this could be—because, ultimately, our exchange will have to be something like: But, why do you believe THAT? “No reason. It’s just one of those bedrock beliefs that don’t need reasons.” And that could never be satisfying. (Right?)

Self-Evident Truths: But, many philosophers believe that there ARE some truths like this. We call them ‘self-evident’ truths. They don’t NEED justification since it’s just OBVIOUS to us that they’re true. For instance, or .

Problem: But, how do we know when a proposition is self-evident? When it really really SEEMS true? But, it really really SEEMS true that there are external objects—and, if we’ve learned anything in this course it is that surely this is a claim that DOES need further justification! Furthermore, lots of claims have seemed self-evident in the past, but are now rejected; e.g., ‘All events must have a cause’ (which many physicists will say is false—the Big Bang is a counter-example, for instance).

In short, we need some justification for thinking that a proposition is self-evident. We will need to be able to identify some feature that it has, which other propositions lack. But, then, the identification of that feature will itself be our REASON for believing it—so, by definition, it will not be a foundational truth. In short, foundational justification (like infinite and circular) just seems impossible. In sum, since our beliefs are neither justified by an infinite chain, a finite chain, or a circle (the only three possibilities), none of our beliefs are ever justified at all!

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2. The Problem of the Criterion: Huemer tells us to imagine that you have a magic 8- ball. You ask it questions. Does 2+2=4? “Definitely,” it says. Will the sun rise tomorrow. “It’s extremely likely,” says the 8-ball. Imagine that all of your beliefs are formed in this way. (For an even simpler version, imagine flipping a coin to answer yes or no questions.) Do you KNOW that 2+2=4? Have you formed KNOWLEDGE? Seemingly not.

Why not? Because the process by which you formed these beliefs does not seem to be of the right sort. Imagine that someone raises doubts about your belief-forming process. “No, it’s totally reliable!” you say. “Look: I’ll ask the 8-ball. Are you reliable?” …“Absolutely,” it says.

For obvious reasons, this is not conclusive. You cannot consult the 8-ball to see whether the 8-ball is reliable! But, now consider how YOU form beliefs. You use your faculties of reasoning to form beliefs. But, how do you know that you are justified in accepting the beliefs that are produced by this faculty? To answer that, you must consult your faculty of reasoning! This is ‘The Problem of the Criterion’:

The Problem of the Criterion: How do we determine when we have knowledge (or justification), and when we do not? What are the criteria for determining this?

In order to for a belief to be justified, you must have good evidence that the faculty by which this belief was formed is reliable. As Huemer puts it, “I am justified in accepting a belief by method M only if I first know that M is reliable.” But, in order to do that, you would need to already know INDEPENDENTLY which beliefs are true and which beliefs are false; i.e., you would need to COMPARE the verdicts produced by your cognitive faculty with the TRUTH. If our comparison shows that the faculty produces ALL (or nearly all) true beliefs, then we will be justified in deeming it reliable, and trusting its verdicts. But, to do this, we would have to use exactly the same faculty!

Contrast this with the 8-ball method, where you easily judge it to be a bad method, because you have used a DIFFERENT faculty—namely, your faculty of reasoning—to see that the 8-ball will very frequently give the wrong answers. But, you can’t step outside of your faculty of reasoning to see whether or not your faculty of reasoning frequently gives the wrong answers. (Or, if you DO have some other, independent faculty, we could only be justified in that IT is reliable if there were still some THIRD, independent faculty to judge it… And so on. We’re off on an infinite regress.)

In short, none of our beliefs can ever be justified because I have no way to determine whether the process or mechanism which produces them is reliable.

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3. Skepticism is Self-Defeating: Both of the above arguments claim to support the conclusion that NO belief is EVER justified—not a single one of them! But, then, the skeptic is committed to the conclusion that no one can ever be justified in believing:

Skepticism is true.

If NO beliefs are EVER justified, then this includes belief in the premises or reasons which the skeptic presents on behalf of her position, as well as the belief in skepticism itself. In other words, skepticism is self-defeating!

Reply: Socrates is famous for saying, “The only thing I know is that I know nothing.” (In fact, the closest he comes to saying this is this: “I do not think I know what I do not know.” Apology, 21d) That would be a dumb thing to say. “I know that I know nothing” is a logically contradictory statement. But, that’s not what the skeptic is claiming. We’re just saying something closer to what Socrates ACTUALLY said. Something like:

“I do not know a single thing.”

Rebuttal: The charge that skepticism is self-defeating is not the claim that it asserts a logical contradiction. Rather, the charge is that belief in it could never be JUSTIFIED!

Reply: But, the skeptic can play the game of reasoning—after all, YOU the reader understand all of the skeptic’s premises. We can force YOU toward the conclusion of skepticism and then, having climbed the ladder, “kick the ladder away” so to speak.

Rebuttal: You can’t appeal to the READER’S understanding of the premises or their justification, or your own PAST SELF’s understanding. The fact remains: You, the skeptic, PRESENTLY are not justified in believing that skepticism is true, nor any of the premises which yielded that conclusion.

Reply: Perhaps the ONLY justified belief is the belief that all OTHER beliefs are justified.

Rebuttal: First, neither of the two arguments for global skepticism that we just looked at build in any kind of exception. Both arguments entail that ALL beliefs are unjustified.

Second, this would be a completely ad hoc and arbitrary exception. (The fallacy committed here is called “special pleading”.)

[Note that this charge that skepticism is self-defeating, if successful, applies only to those global versions which say that ALL of our beliefs are unjustified. External world skepticism, on the other hand—i.e., the claim that only our beliefs about EXTERNAL, MATERIAL OBJECTS are unjustified—remains unscathed. It is not self-defeating.] 4