One thing they have in common is that many philosophers find it easy to dismiss one or both of them. I think they are both suspected of, as critics of Cavell often call it, self-indulgence. People feel: well, I could do that, too, if I gave in to temptation and allowed myself to talk or think so outrageously. Once the suspicion is voiced, however, it seems silly. Which one of us is capable of talking or thinking the way either of them do? What is to be resisted is rather the temptation to reach for an easy way of dismissing thinkers, our own contemporaries, of such terrifying power.
Beyond that, two points stand out immediately, one about rational disagreement and one about ordinary language. The two cant really be separated, but I dont know how to develop them together, either, so Im going to start here with the first and hopefully get to the second in another post.
Both Lewis and Cavell are concerned to explain how a form of argument can be fully rational even though it doesnt (even ideally, in the long run, etc.) embody any guarantee that the parties will eventually agree.
This doesnt mean that they think agreement is wholly irrelevant as an aim in such cases. Cavell says that without the hope of agreement, argument would be pointless (Cavell, Claim of Reason, 254, my emphasis). Lewis, similarly, describes the general point of argument, or at least debate, as follows: each of two debaters tries to get his opponent to grant him to join him in presupposing parts of his case, and to give away parts of the contrary case (Scorekeeping in a Language Game, Phil. Papers 1:239). But the argument has been worthwhile even if the hope is frustrated, and so the lack of definite procedures for reaching an agreement is no defect in the rationality of the method. (Both think there are such procedures in at least some other cases.)
The target form of argument is not the same: for Cavell, it is moral argument; for Lewis, philosophical argument in general, one may gather, but the only examples he ever discusses in detail are debates over ontic parsimony (Holes, Phil. Papers 1:9). (Although Holes is co-authored with Stephanie Lewis, I assume that everything in it speaks for both authors.)
Cavell emphasizes that the failure of agreement in moral argument has been used to impugn its rationality, based in part on the premise that the rationality of an argument depends upon its leading from premisses all parties accept, in steps all can follow, to an agreement upon a conclusion which all must accept (CoR, loc. cit.). Lewis doesnt emphasize the corresponding fact about ontic debates, but he might and he knows that he might. What Cavell quotes Stevenson as saying, namely that disagreements in science are disagreements in belief, whereas disagreements in ethics are disagreements in attitude (CoR 259, citing Stevenson, Foundations of Ethics, 7), was said first by Carnap, and, at first, only about ontology, rather than about ethics.
What does an argument accomplish when it doesnt, and wouldnt even when all was said and done, result in agreement? Argle has said what we accomplish in philosophical argument: we measure the price (Lewis, Introduction to Phil. Papers 1, p. x). That is either the same as, or very similar to, what Cavell says about the process of questioning a claim to moral rightness in the course of a moral argument.
assessing the claim is, as we might now say, to determine what your position is, and to challenge the position itself, to question whether the position you take is adequate to the claim you have entered. The point of the assessment is not to determine whether it is adequate, the point is to determine what position you are taking, that is to say, what position you are taking responsibility for and whether it is one I can respect. (CoR, 268)
The last clause strikes a note which is not mostly heard in Lewis, namely the possibility that the argument will leave us no longer on speaking terms. I want to say more about this in my next post on this topic, on ordinary language (it has to do with the tragic outcome that we find we cannot speak for one another). But Lewis does consider the stakes in ontic debate to be that high, at least among academics (note that academic is normally a term of disparagement for Cavell, but not for Lewis). This is clear, for one thing, from the elaborate care which Argle and Bargle take, in Holes, to avoid such an outcome, and for another thing from the care which Lewis himself takes to remain in conversation with a wide array of competing philosophers (Armstrong, Plantinga, Van Inwagen, Lycan, Reutley, etc.), while at the same time tacitly excluding others. (After a single response, in Convention, to Must We Mean What We Say?, Cavell is among the excluded.) More explicitly: Lewis holds that the main or, at least, only fully sufficient reason that debate is allowed to continue in academic philosophy is the tacit treaty by which various schools of thought agree not to prefer one over the other in hiring. But the treaty clearly doesnt extend to any school whatsoever: Maybe, Lewis suggests, the treaty is limited to respectable schools of thought, as opposed to ratbag notions (Academic appointments: Why ignore the advantage of being right?, Papers in Ethics and Social Philosophy, 199 n. 7). Lewis says there that I dont come to respect your position by coming to give some credence to it (he respects Graham Priests hard-line paraconsistency even though he considers it certainly and necessarily false). He doesnt say exactly how I might come to respect it. But how else, if not by the methods of Argle and Bargle?
The difference between moral argument and ontic debate must be important, but it is difficult to assess just how. Cavell says a lot about the contrasts and similarities between ethics and epistemology, but he remains enough of a good logical positivist to hold that To say a dispute is about a matter of fact is exactly to say that there are certain ways of settling it (CoR, 259). Lewis disagrees:
If you say flatly that there is no god, and I say that there are countless gods but none of them are our worldmates, then it may be that neither of us is making any mistake of method. We may each be bringing our opinions to equilibrium in the most careful possible way, taking account of all the arguments, distinctions, and counterexamples. But one of us, at least, is making a mistake of fact. Which one is wrong depends on what there is. (Introduction to
Phil. Papers 1, p. xi)
The result is that, as far as I know, Cavell never discusses at all the type of argument which for Lewis (after Convention) is always paradigmatic of philosophy.
Lewis, on the other hand, does discuss moral argument, as well as other types of philosophical argument, including epistemological argument, semantic argument, and (obviously, from the above quotes) argument about the methodology of philosophy itself. But it is unclear whether or how these other types of argument are supposed to resemble ontic debate. In Scorekeeping, Lewis imagines a discussion which looks a lot like one of the sample moral arguments from The Claim of Reason. To put it in Cavells form:
A (a corrupt politician): You see, I must either destroy the evidence or else claim that I did it to stop Communism. What else can I do?
B (rudely): There is one other possibility you can put the public interest first for once!
A: I cant do that. (cf. Scorekeeping, 247)
Lewis says about this, first, that As initial statement may be true while his final one is mistaken, because Bs rude reply (the term rude is Lewiss, repeated several times) shifts the boundary between relevant and ignored possibilities, and the boundary, once shifted outward, stays shifted (ibid.). He then goes on to compare this to the case of a commonsensical epistemologist who claims, truly, to have infallible knowledge that the cat is in the carton, but then must concede defeat when the skeptic replies, You might be the victim of a deceiving demon. Again, the skeptic succeeds in shifting a boundary which the commonsensical epistemologist cannot then move back. Then Lewis adds:
We get the impression that the sceptic, or the rude critic of the elected official, has the last word. Again this is because the rule of accommodation is not fully reversible. For some reason, I know not what, the boundary readily shifts outward if what is said requires it, but does not so readily shift inward if what is said requires that. Because of this asymmetry, we may think that what is true with respect to the outward-shifted boundary must be somehow more true than what is true with respect to the original boundary. I see no reason to respect this impression. Let us hope, by all means, that the advance toward truth is irreversible. That is no reason to think that just any change that resists reversal is an advance toward truth.
This sounds vaguely related to Cavell, especially in the concern about reversibility.1 It also sounds quite un-Cavellian, especially in its confidence that the skeptic has succeeded in establishing a context which justifies the objection.
Its hard to know what more to say without understanding exactly what Lewis thinks has gone wrong, in both cases, such that we must (by the rules of ordinary language!) have the impression of a last word, but an impression which nevertheless is not respectable. Toward the truth about what do we hope to advance in such cases? Not toward the truth about what is strictly, absolutely possible: Lewis has an answer to that, and an answer according to which the politician and the commonsensical epistemologist are wrong (there is a possible world at which a counterpart of the politician puts the public good first, and a possible world at which a demon deceives a counterpart of the epistemologist into believing that the cat is in the carton, or rather into having a corresponding belief). Rather, toward the truth about what is morally or epistemically possible for us. And is it still true, in such cases, that, although neither of us makes a mistake of method, and although we continue then to disagree, what there is will make at least one of us wrong? But isnt the question here precisely one of method: a question of which arguments, distinctions, and counterexamples need to be considered, and which can or should be ignored? And so wont what there is, if it makes us wrong, eo ipso make us mistaken in method? Or, to put it the other way around: what is the standard by which Lewis calls the critic rude and the skeptic (p. 245) a player of language games? Suppose as I believe most of us, including Lewis, would want to suppose that the rude critic does force an advance towards truth, whereas the skeptic does not. By what standard is Lewis nevertheless implicating them in a common error (or worse)?
I think we would have to answer such questions before deciding whether the clear success of Lewiss skeptic is inconsistent with the unclear failure of Cavells, and also whether Cavells worries over the difference between the epistemological case and the moral one could find any echo in Lewis.
1 Lewis does not touch, here, on another Cavellian theme, the stability of the conclusion. Elsewhere he makes equilibrium apparently, stable equilibrium the prime goal of philosophical thought: If our official theories disagree with what we cannot help thinking outside the philosophy room, then no real equilibrium has been reached. Unless we are doubleplusgood doublethinkers, it will not last (Introduction, x).