History

Let’s start with some history. Skepticism has roots in classical antiquity. A trilemma by Agrippa (2nd century AD) is one of the earliest formulation of the skeptical challenge. Since every belief is produced by a method or source (say, memory, perception, experiments, divine inspiration, etc.), there are three ways to justify the reliability of a method:

1. to appeal to the method itself (circularity)

2. to appeal to another method (infinite regress)

3. admit the method cannot be justified (basic)

No one of these options seems to be promising.22 Each option, however, could be developed into a broader epistemological research program: coherentism (embracing circularity), infinitism (embracing infinite regress), foundatioanlism (embracing the fact that some beliefs are basic).

Skepticism saw a resurgence in the 16th and 17th century in Europe, in part because of endless religious disagreements and conflicts. The philosopher Montaigne (1533–1592) saw the challenge clearly:

If I cannot give reasons for why I think my methods are reliable, then it is not clear how my committments to those methods can be understood as rational. And that, in turn, raises the question of how even changing your mind about which methods to trust can be a rational process, as opposed to something more like religious conversion. (p. 45)33 There are two problems here. Problem 1: how do we justify the reliability of a method we rely on (say empirical observation)? Problem 2: if we decide to change our method of inquiry (say from trusting divine revelation to performing scientific experiments), how can we rationally justify this change?

The most well-known response to skepticism was given by Descartes (1596–1650):

the foundation of knowledge, for Descartes, is our priviledged access to the contents of our own minds… He looked within himself and found the idea of perfection….So if anything causes the idea of perfection, it must itself be something perfect…and so a perfect being—God—must exist. And if he exists, and is perfect, then he would not deceive us. So what is clearly and distinctly perceived must really be true. (p. 48)44 This is a very quick summary of Descartes’ Meditations on First Philosophy.

Descartes’ method consists in following the guidance of clear and distinct ideas. But the justification of this method runs into a circle (which was the first lemma of Agrippa’s trilemma).55 The circle is this: we need to establish the existence of God to ensure that we can trust ideas that appear to us as clear and distinct, and we need to rely on clear and distinct ideas to establish the existence of God.

Perhaps, Descartes’ response to skepticism failed because it was too ambitious–it aimed to identify a method that would deliver infallible knowledge. But what about a more modest method—say trust your observations and generalize from them, called the method of induction? Induction can only deliver probable beliefs, but that might be enough. So, can we can justify induction against the skeptical challenge? We cannot even do that, as Hume (1711–1776) taught us:

Hume is suggesting that we don’t even have any reason to believe it is probable that bread will nourish us tomorrow, that our breaks will stop our car, that the sun will rise tomorrow. We have no reason for it because we possess no noncircular reason to believe in the principel of induction. (p. 50)66 Can you reconstruct more precisely Hume’s skeptical argument against induction?

Contemporary relevance

What is the relevance of the skeptical challenge today? To appreciate its relevance, it is better to view skepticism as a challenge directed against our ability to provide reasons, rather than identify reliable methods.77 To motivate this shift—from identifying reliable methods to providing reasons—imagine you are engaged in a debate with someone who believes the earth is flat, denies the efficacy of vaccines, or rejects the theory of evolution. What kind of non-circular reasons could you invoke to convince them that they are wrong? See the long example on pp. 53-54 about a young earth creationist. Then, the skeptical challenge can be put as follows:

You can defend a fundamental epistemic principle under challenge only if you can give a reason for that principle. Fundamental epistemic principles can be shown to be true only via circular arguments. Circular arguments can’t be used to give reasons for believing anything. If I don’t trust your methods, and therefore accept your principles, your reassuring me that they are reliable because employing them tells you so won’t impress me. Nor should it. (p. 56)

Here the problem is not so much whether a given method is reliable. Rather, the problem is this: how person \(A\) can rationally persuade person \(B\), where \(A\) follows a method \(M\) which \(B\) does not follow. Persons \(B\) must be rationally persuaded about method \(M\) by person \(A\) via noncircular reasons which \(B\) can (and should) recognize as reasons for relying on method \(M\). The skeptic holds there is no way to answer this problem–that this is an impossible task.

If the skeptic is right, two alarming consequences follow: (1) Disagreement over fundamental epistemic principles cannot be rationally resolved (p. 56). (2) It is hard to see how changing our own minds about fundamental epistemic principles can be rational (p. 57).

Tradition

Tradition is important in many respects. Even scientific practice is grounded in tradition: scientists train other scientists. The problem arises when tradition itself is used as a justification of tradition, making tradition the only ultimate ground of justification. Then, tradition would become unassailable and unchangeable:

The obvious questions to ask the conservative traditionalist is, How do you know which tradition to follow? (p. 65)

Two philosophers are relevant in this respects. First, Rorty defines “Reason” itself as a form of Western tradition:

there is nothing to my use of the term “reason” that could not be replaced by “the way we Western liberals, the heirs of Socrats and the French revolution conduct ourselves”…all reasoning, both in physics and ethics, is tradition-bound. (p. 67) 88 Rorty (2000), Universality and Truth in Rorty and his Critics (ed. Brandom), Blackwell.

This raises a question. When the Western tradition is challenged, how can that challenge be answered? Rorty will likely reply that the challenge cannot be answered in a non-circular way—that is, without invoking principles of the Western tradition (i.e. Reason) itself. But here we are back to the first lemma of Agrippa’s trilemma.

Wittgenstein offers a different perspective (pp. 68-69):

If the true is what is grounded, then the ground is not true, nor yet false.99 Wittgenstein, On Certainty, n. 205

[O]ur doubts depend on the fact that some propositions are exempt from doubt, are as it were like hinges on which those turn.1010 ibid, n. 341

When two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and a heretic. I said I would “combat” the other man—but wouldn’t I give him reasons? Certainly, but how far do they go? At the end of reasons, comes persuasion. (Think of what happens when missionaries convert natives.)1111 ibid, n. 611-612

So, when reasons end, the “big stick” comes out.1212 A Lynch puts it: “You can’t just sit around and talk to the Nazis” (p. 69) Reason is replaced by persuasion, manipulation, power, brute force.1313 This is in line with Povinelli’s claim: the liberal who professes to be neutral, tolerant, open to reasons, is actually imposing, by brute force, a one-sided position onto others who disagree. But this capitulation to power is inconsistent with democratic politics:

Political claims on you cannot be justified, in a democracti conception of politics, by simply wielding or threatening brute force…Rather, I must try to persuade you that my view is rational. Only then do I treat you as an autonomous being, a being who is capable of judging waht to believe.

So, appeals to tradition runs into trouble: either Aprippa’s circularity problem comes up again (this seems the implication of Rorty’s position) or reason is ultimately grounded in persuasion, manipulation, power or force (following Wittgenstein), and this conflicts with the presuppositions of democratic politics.

Common sense

The philosopher Reid (1710–1796), a contemporary of Hume, answers the skeptical challenge by an appeal to common sense, understood as the set of epistemic principles that we cannot do without because of they way we are constituted as human beings:

there are some principles … which the constitution of nature leads us to believe, and which we are under a necessity to take for granted in the common concerns of life, without being able to give a reason for them; these are what we call principles of common sense. (p. 73)1414 Reid (1764), Inquiry Into the Human Mind

Three objections can be raised against this approach. First, the indispensability of a principle isn’t necessarily a reason for concluding that the principle is true.

Second—perhaps most importantly—the indispensability of a principle isn’t a reason that can be given in defense of the principle. In fact, Reid himself admits that we are not “able to give a reason” for the principles of common sense.1515 What would be the difference from mere faith in common sense, then?

If you say that it is self-evident that S is reliable because we all must take it for granted that S is reliable, then what do you do if someone challanges you on this “fact”? (p. 76)

The third problem is that common sense principles are generic. Common sense might tell us we need to trust observation. Very well, but disagreements that matter aren’t usually about whether we should trust observation. Disagreements are more fine-grained than that. They are about to what extent and in what circumstances we should trust observation.

The hard questions concern whether we shoud trust observation more or less than other sources of belief in specific context…the hard cases concern what I have called comparative fundamental principles. (p.77)1616 So, if neither tradition nor an appeal to common sense are an adequate response to skepticism, what do we do? We are left empty-handed. Lynch in his book has an answer. If you are curious, read chapters 5 and 6.