Some Responses to Skepticism

Here, I explain what’s wrong with three arguments for skepticism in epistemology.*

[ *Based on Skepticism & the Veil of Perception, ch. 8. ]

The kind of skepticism at issue claims that we have no justification for any contingent propositions about the external world, and possibly about anything. I’ve discussed what’s wrong with the brain-in-a-vat argument elsewhere ( 1 ) ( 2 ), so let’s leave that one aside. Here, I’ll talk about three other arguments for skepticism.

1. The Regress Argument

1.1. The argument

Some beliefs are justified by reasons (other beliefs that support them), in which case those reasons may be justified by further reasons, and so on. This leads us to ask what might be the overall structure of the series of reasons for any given belief. The skeptic argues:

1. The series of reasons for a belief may have one of three structures:

   1. Circularity (some belief stands in its own evidential ancestry),

   2. Infinite regress (every reason has a reason behind it, with no repetition),

   3. Foundations (or a finite, linear structure; the series has an ultimate starting point, for which there are no reasons).

2. Circular reasoning cannot generate justification.

3. An infinite regress is impossible.

4. Foundational structures also cannot generate justification, for

   1. A belief is justified only if there is some reason for it, and

   2. If a belief is not justified, then it also cannot provide justification to any other beliefs.

5. Conclusion: No belief is ever justified to any degree.

1.2. Reply

You probably know which step in that is wrong: it’s #4, and in particular 4a.

But if a belief isn’t justified by a reason, in what way is it justified? The answer is that a belief may be justified by a type of experience, specifically, by appearances, which are the mental states you report when you say something “seems” or “appears” to you to be the case. In the case of the external world, we have sensory experiences by which the external world appears to us to be certain ways. In the absence of specific grounds for doubt, it’s reasonable for us to presume that things are the way they seem. ( 1 ) ( 2 )

What is supposed to be wrong with that answer? There’s supposed to be a dilemma: either (a) you know that you have the appearance, or (b) you don’t know this.

(a) If you know you have the appearance, then that’s another justified belief that serves as a reason, and then we have to ask how that is justified. If the answer is that you have another appearance (the appearance of an appearance), then the regress continues.

(b) If you don’t know that you have the appearance, then, skeptics say, the mere existence of the appearance (unbeknownst to you) can’t make any difference to what you’re justified in believing.

This is a very weird way of thinking, and “do you know you have an appearance” is a very weird question. These “appearance” states are conscious mental states, so it would not be sensible to describe them as happening “unbeknownst to you”. But it also isn’t as if you have to form some distinct belief state about your experiences. Not all awareness has to be beliefs or conceptual representations. The experience alone directly justifies a belief with a content entailed by the content of the experience; it doesn’t have to first go through a belief about the experience.

2. The Reliability Argument

2.1. The argument

We have a limited number of cognitive faculties or belief-forming methods. E.g., there’s the method of “observation using the 5 senses,” the method of “deduction from previously-existing beliefs”, the method of “memory,” etc. A method is said to be “reliable” if it would generally produce true beliefs, if used repeatedly.

The skeptic argues:

1. All beliefs are formed using some method.

2. To acquire a justified belief that P using method M, you must first have justification for thinking that M is reliable.

3. Method circularity cannot generate justification.

   1. This would be where you use a method to verify its own reliability, or use two methods to verify each other’s reliability, etc.

4. There can’t be an infinite series of methods.

5. So justification is impossible.

2.2. Reply

The false step has to be #2. (2) seems plausible when you think about certain methods, such as the method of “consulting the Magic 8-Ball”. When you use that method, you have to have evidence that the 8-ball is reliable. This is what you might call a non-foundational method; it is supported by further reasoning.

But some methods are foundational, in that one may rationally start with these methods. The foundational methods, in my view, all consist of presuming that things are the way they appear in the absence of specific grounds for doubt. But if you think there are some other foundational methods, that’s okay for present purposes.

Suppose there is some way to acquire justified beliefs; it doesn’t matter what it is. Let’s call that way “M”. Premise 2 entails that M is actually not a way to acquire justified beliefs, since premise 2 implies that, rather than merely using M, one must instead use the following more complicated method: first, verify that M is reliable; then believe the propositions that M produces.

This cannot be correct, because we already stipulated that M is a way to acquire justified beliefs. By definition, it cannot be that anything more is required. So premise 2 is close to incoherent; or rather, it just by itself entails that there are no methods to acquire justified beliefs.

2.3. Epistemic circularity

So you do not in general need to first verify that a method is reliable before acquiring justified beliefs using it. Nevertheless, suppose I want to know that my foundational belief-forming methods are reliable. Surely I should be able to learn that. Surely, for example, we now know that the five senses are generally reliable, deductive reasoning is generally reliable, etc. None of these things, obviously, is 100% reliable. But equally obviously, they are over, say, 90% reliable. (I certainly hope that fewer than 10% of your sensory experiences are hallucinations.)

How can one know such things?

It looks like the answer has to be: through epistemic circularity. I.e., you can use a method to verify its own reliability, or use two or more methods to verify each other’s reliability. This must be the answer, since

(i) given the extreme breadth of the term “method”, all beliefs, even foundational beliefs, count as being formed by some “method”;

(ii) there clearly aren’t an infinite series of methods (there might in fact be just five methods: observation, introspection, memory, intuition, and reasoning).

Since I know, e.g., that observation is generally reliable, and I could only know this through epistemic circularity, it must be that epistemic circularity is sometimes acceptable, in that it produces knowledge.

Note: premise circularity is not acceptable. This is where an argument contains the conclusion as one of the premises, or one of the premises is justified by the conclusion.

However, “epistemic circularity” is not premise circularity. Epistemic circularity includes cases where a rule of inference is used in inferring that that rule is cogent, as well as cases in which a belief-forming method is used in the process of determining that that same method is reliable. This is not viciously circular, given that one does not, in fact, need to verify the reliability of the method in order to form justified beliefs using that method.

3. Hume’s Argument

3.1. The argument

Hume’s argument for external-world skepticism assumes indirect realism (see arguments for IR here). It went something like this:

1. We are only ever directly aware of our own ideas and impressions. (Or: our own sensory experiences.)

2. If (1) is true, then we can know about the external world only if we can know that certain impressions are signs of certain kinds of external objects.

3. The only way to know that A is a sign of B is to observe instances of A followed by instances of B.

4. So we cannot know about the external world.

   1. Comment: We can’t observe instances of external objects being followed by certain sensory impressions, because, allegedly, we never actually observe the external objects. We only ever observe one side, the mental items, so there’s no way of knowing what might cause these mental things.

3.2. Reply

The false step is #1. As discussed earlier, in perception, we are directly aware of external phenomena.

How do we know about external objects, then? We have justified, true beliefs about them, with no defeaters. The way we have these justified beliefs is that we have sensory experiences representing external objects, whereby those objects seem present to us. We (usually) have no specific grounds for doubting the appearances; thus, we are justified in believing that certain external objects are present. We do not have to construct arguments that our sensory experiences are signs of external objects.

. . .

In conclusion: Skeptics are confused. Don’t be a skeptic.