23

Epistemic Rules INTRODUCTION According to a very natural picture of rational belief, we aim to believe only what is true. However, as Bernard Williams used to say, the world doesn’t just inscribe itself onto our minds. Rather, we have to try to figure out what is true from the evidence available to us. To do this, we rely on a set of epistemic rules that tell us in some general way what it would be most rational to believe under various epistemic circumstances. We reason about what to believe; and we do so by relying on a set of rules.’ Although there is some controversy about exactly how these rules are to be formulated, we take ourselves to know roughly what they are. For example, we have a rule linking visual appearances to beliefs: (Observation) If it visually seems to you that p, then you are prima facie rationally permitted to believe that p. We have some sort of inductive rule linking beliefs about the observed to beliefs about the unobserved, an example of which might be: (Induction) For appropriate F’s and G’s, if you have observed n (for some sufficiently large n) F’s and they have all been G’s, then you are prima facie rationally permitted to believe that all F’s are G’s. We also have deductive rules, such as: (Modus Ponens): If you are rationally permitted to believe both that p and that If p, then q', then, you are prima facie rationally permitted to believe that q.2 These rules, and others like them, constitute what me may call our epistemic system. They represent our conception of how it would be most rational for a thinker to form beliefs under different epistemic circumstances. Let us call this the rule following picture of rational belief. It is a very familiar picture and has tempted many. As I shall try to explain later, its roots run very deep.3 Because we accept this picture, we take seriously a number of questions that it seems to entrain. For example, we recognize that, in addition to the rules that we actually use, there are other rules, different from and incompatible with ours, which we might have used instead. And this seems to raise the question: Are our rules the right ones? Are they the ones that deliver genuinely justified belief? These questions in turn raise a more fundamental one: In what sense could there be a fact of the matter as to what the right epistemic rules are? And if there is such a fact of the matter, how do we find out what it is? And what, in any case, entitles us to operate with the rules that we actually operate with? None of these familiar and compelling questions would make much sense in the absence of the rule-following picture of rational belief. Each of them presupposes that we rely on rules in forming rational beliefs. I find the rule-following picture, along with the questions that it entrains, as natural and as compelling as the next person. However, I have also come to worry about its ultimate intelligibility, a worry that I find myself unable to lay to rest. In this paper, I aim to explain the considerations that give rise to this worry. I have been talking about the rule-governed picture of rational belief. But rational belief is hardly the only domain in which rule-following has been thought to play a prominent role. The sort of generalist picture I have been sketching for epistemology has of course always loomed large in ethics. We find it very natural to think that, in our moral judgments, we are guided by a set of general moral principles that tell us what we have most reason to do under various practical conditions. Recent writers have complained about this generalist picture in ethics. They say that moral reasons are too holistic for there to be general principles that can tell us what it would be morally correct to do under varying practical conditions.4 That is not the sort of problem I have in mind for the generalist picture of rational belief. Rather, I will develop two other types of difficulty. The first concerns how to understand the notion of a "rule" as it is used in the rule-following picture. What exactly is it that we are being said to follow, when we are said to follow epistemic rules? The second difficulty concerns what it is to follow a rule regardless of how exactly a rule is construed. My worry here is closely related to the famous discussion of following a rule that was inaugurated by Wittgenstein and brilliantly expounded by Saul Kripke.5 Like Kripke, I think that there really is a skeptical problem about rulefollowing that can be derived from Wittgenstein's discussion. But my problem is not Kripke's. Unlike Kripke's problem, my problem arises in an especially virulent form for epistemic rules, as opposed to rules of other kinds. And it cannot be solved, as Kripke's problem can, by our helping ourselves to various forms of anti-reductionist conceptions of meaning or content. All of this is what I propose to explain in what follows. 1. WHAT DO WE FOLLOW: IMPERATIVES OR NORMATIVE PROPOSITIONS? Imperatives vs. Norms We talk interchangeably about epistemic rules and about epistemic norms. Are these the same sorts of thing or are there important differences between them? This is an area in which our language is sloppy and we are not often very explicit about what we mean. Take the word "rule." By and large, when Kripke talks about "rules" he is talking about general imperatival contents of the form: If C, do A! whereC’ names a type of situation and `A’ a type of action. On this construal, rules are general contents that prescribe certain types of behavior under certain kinds of condition. However, not everything that we call a rule in ordinary language conforms to this characterization. For example, we talk about the “rules of chess.” One of these rules is: (Castle) If the configuration is C, you may castle. This does not look like an imperative. Unlike an imperative, it seems truthevaluable. It looks more like something we should call a normative proposition or norm, for short. It is a norm of permission. In addition to the permissive norms, of course, there are norms of requirement: (First Move) At the beginning of the game, White must make the first move. Arguments for the Propositional Construal We need, then, to recognize a distinction between two different kinds of content-the imperatival and the propositional; and we need to clarify whether, in talking about epistemic rules, we are talking about contents of the one type or the other. When I gave a rough characterization of these rules above, I gave them a normative propositional formulation. There are at least three considerations that favor this construal. To begin with, epistemic justification is a normative notion. We would expect, therefore, that the contents that encode our conception of it would be normative contents. However, imperatives are not normative in any way. They are merely commands or instructions.6 If such commands or instructions do play a role in our epistemic systems, it is natural to think of them as having a derivative status-a status derived from the more fundamental normative propositions that encode our conception of epistemic justification. The second reason for favoring a propositional construal has to do with our need to distinguish between different kinds of action-guiding or beliefguiding rules. Thus, there are epistemic rules, prudential rules, aesthetic rules, moral rules and so forth. It is easy to distinguish among these types of rule in propositional terms, by building their identity into their propositional content. Thus, an epistemic rule would be a normative proposition of the following kind: If C, then S is epistemically permitted to believe that p. A prudential rule, on the other hand, would involve the concept of a prudential permission; and so forth. By contrast, it is hard to see how to get this differentiation on an imperatival picture. The trouble is that all imperatives are alike-they all assume the form If C, do A! And so the mere content of an imperative is incapable of telling us whether it’s an epistemic, prudential or moral imperative.7 A third reason for favoring a propositional construal of epistemic rules has to do with the need to capture not only requirements but permissions as well. The trouble, however, is that there looks to be a real difficulty capturing a norm of permission in imperatival terms. The difficulty, in a nutshell, is this: An imperative, by definition, tells you to do something, if a certain condition is satisfied. However, a norm of permission doesn’t call on you to do anything; it just says that, if a certain condition were satisfied, then performing some particular action would be alright. Thus, obviously, the norm of permission (Castle) cannot be expressed in terms of the imperative If configuration is C, Castle! because that would suggest that whenever the configuration is C one must castle, whereas the norm merely permits castling and does not require it. Could we perhaps express (Castle) as: Castle!, only if C. But this seems to want to embed an imperative in the antecedent of a conditional: If Castle!, then C and I don’t know what that means. Gideon Rosen has suggested another strategy for the imperativalist-using complex imperatives with disjunctive consequents.8 Thus, he suggests that the imperative that corresponds to an epistemic norm of permission of the form: (4) If for some e, f(e, h), then it is rationally permissible to believe h (on the basis of e) would be something more like this: (5) If for some e, f(e, h), then either believe h (on the basis of e), or suspend judgment about h. Now, I take it that “suspending judgment” about h isn’t simply: not believing h. If it were, then the imperative at (5) would amount to saying: If e, then either believe It or don’t believe h! which doesn’t say much of anything. Suspending judgment, then, requires something activeconsidering whether h and then rejecting taking a view on the matter. If that’s right, though, (5) now seems to call for you to do things that go well beyond what (4) says. According to (4), if a certain kind of evidence is available, then, if you believed It on its basis, that belief would be justified. (4) does not say that you should believe h; it doesn’t say that you should consider whether h; it doesn’t say that you should do anything. In other words, (5) is most naturally seen not as the imperatival counterpart of the norm of permission formulated in (4) but as the imperatival counterpart of the norm of requirement formulated in (6) If for some e, f(e, h), then you are required either to belief It (on the basis of e) or to suspend judgment on h. Would we do better with something more along the lines of (7) rather than (5)? (7) If for some e, f(e, h), then either believe h (on the basis of e) or don’t do anything (on the basis of e)! But this doesn’t seem right, either. Even without going into the details of what it might mean for someone to “not do something on the basis of e”, I hope it’s clear that, whatever exactly it means, if, in response to e, I scratched my nose on the basis of e, I wouldn’t have done anything that is in violation of the norm of permission issued by (4). There are, no doubt, many other proposals that could be considered, but I hope it is clear that there really is a problem capturing a norm of permission in imperatival terms. An imperative, however disjunctive its consequent, will require you to do something, or to refrain from doing something; but a norm of permission doesn’t say anything about anyone’s doing anything, or refraining from doing anything. It just says that, under the appropriate conditions, if one were to do something, doing that thing would be alright.9 Arguments for the Imperatival Construal These, then, are some of the considerations that push one in favor of a propositional view of rules. On the other hand, there is the following argument that pushes one in the opposite direction. Recall that the picture we are working with says that it is necessary and sufficient for a belief to be rational that it be held in accordance with the correct epistemic rules. In other words, we are working with: (RuleRatBel) S’s belief that p is rationally permitted if and only if S arrived at the belief that p by following the correct rule N. Now, suppose we take N to be an epistemic normative proposition of the form: (EpNorm) If C, then S is rationally permitted to believe that p. Now, EpNorm-the norm we are said to be following-says that it is sufficient for my being rationally permitted to believe that p that condition C obtains. However, the rule-following picture of rational belief (RuleRatBel) implies that it is not sufficient for my being rationally permitted to believe that p that C obtains-in addition, I need to have followed the rule EpNorm. If we put these two facts together, we get the following peculiar result: The only way to implement the rule-following picture of rational belief, with the rules construed as normative propositions, is to accept that the normative propositions that we are required to follow, in order to acquire rational belief, must be false epistemic propositions! To have rationally permitted beliefs a thinker is required to follow false epistemic normative propositions. And that is surely very odd. How could it be that, in order to arrive at genuinely rationally permitted beliefs, I must be armed with, and guided by, a set of false epistemic propositions about the conditions under which a belief would be genuinely epistemically justified? It is important to note two points. First, the problem here is structural. Whatever proposition we replace (EpNorm) with, we will face some version or other of this false rules problem, because the rule-following picture will always insist on imposing a further necessary condition on rational belief beyond that recognized by the proposition that is said to constitute an epistemic rule-namely, the condition that that rule be followed.10 Second, this problem of false rules would not arise on the imperatival picture of epistemic rules, on which the rules are of the form: If C, believe that p! Since, on this conception, the rules themselves don’t make any claims, they can hardly conflict with the claims being made by the rule-following picture of rational belief (RuleRatBel) about the conditions necessary for rational belief. That constitutes a significant argument in favor of an imperatival construal of epistemic rules. The trouble is that, on such a construal, we would face all the other problems outlined above. This, then, is the first difficulty I wanted to raise for the rule-following picture of rational belief: it is very unclear what satisfactory answer we can give to the question: What sort of content can a rule be such that following it is necessary for a belief to be rational?11