Tuesday, August 18, 2015

The Certainty Norm of Assertion

In a well-known paper, Jason Stanley argues against the knowledge norm of assertion, in favour of a certainty norm of assertion. As Jason notices, knowledge-denying Moore-paradoxes like (1) aren't the only Moore-paradoxes in town; certainty-denying conjunctions like (2) seem similarly paradoxical:

  1. Jason works at Yale but I don't know that Jason works at Yale
  2. Jason works at Yale but it's not certain that Jason works at Yale

Jason thinks that knowledge doesn't entail certainty, and so a knowledge norm of assertion can't explain what's wrong with assertions of (2). Instead, he opts for a certainty norm of assertion, that's meant to explain both.

The argument I thought I remembered from the paper was that the certainty norm was strictly stronger than the knowledge norm. The certainty norm explains (2) in the obvious way (just like the knowledge norm explained (1)); and it explains (1) by invoking the entailment of knowledge by certainty. If I don't know that Jason works at Yale, it's not certain, so I can't assert the first conjunct. But today I read the paper again, and that's definitely not the argument. Certainty, in the sense Jason discusses, does not entail knowledge.

The relevant notion of certainty here is 'epistemic certainty', according to which 'one is certain of a proposition p if and only if one knows that p (or is in a position to know that p) on the basis of evidence that gives one the highest degree of justification for one's belief that p'. (p. 35) Since certainty does not entail knowledge, on Jason's view, it is not quite clear to me how a certainty norm explains the infelicity of (1). Of course one can't know both conjuncts in (1), but I don't see why why one couldn't have certainty in both conjuncts. Here is Jason's attempt to deal with the issue:
Consider the proposition that there are no large Jewish elephants in my bedroom. This may have been an epistemic certainty for me five minutes ago, even though I did not know that there were no large Jewish elephants in my bedroom. I did not know that there were no large Jewish elephants in my bedroom, because I did not believe it, and I did not believe it simply because it didn't occur to me ever to entertain that possibility. Nevertheless, in this case, if I had entertained the propsition that there are no large Jewish elephants in my bedroom, I would have known it. The reason this counterfactual is true is because it is an epistemic certainty for me that there are no large Jewish elephants in my bedroom. So the fact that a proposition is an epistemic certainty for a person does not entail that the person knows that proposition. If a proposition is an epistemic certainty for a person at a time, then it does follow that the person is in a *position to know* that proposition. Being in a position to know a proposition is to be disposed to acquire the knowledge that the proposition is true, when one entertains it on the right evidential basis. Since epistemic certainty entails possession of this dispositional property, utterances [like (1)] are odd. (p. 49)
The thought seems to be that if something is certain, then if one asserts it, one must know it. But it doesn't follow from his explanations of these notions that this must be so—couldn't something be asserted without being entertained on the right evidential basis? Suppose for instance that p is certain for me, but I don't know p because I am ignoring my overwhelming evidence for p, and basing my belief that p on some bad evidence. Couldn't it be, in this case, that it's also certain for me that I don't know p? I think it seems plausible that I might—my evidence, which, suppose, includes some sort of introspective access to the source of my belief—might overwhelmingly establish that I don't know that p. But if so, the certainty norm predicts that 'p but I don't know that p' should be assertable.

Thursday, August 06, 2015

Assertability without Assertion

I think there are cases where one doesn't assert something, but one wouldn't be in violation of any norms of assertion if one did. Probably you can think of lots of cases like that. For instance, suppose that Helen is having a conversation about sloths and their habits. Suppose that she has whatever arbitarily high epistemic access you like with respect to the fact that urinate only once a week, but chooses not to mention this fact, preferring in this instance to listen to the other people speaking instead. If she had asserted it, this would have amounted to an expression of her knowledge or better (certainty, maybe), and it would have given knowledge to her interlocutors, who would have celebrated this fact as relevant and interesting. But she keeps it to herself instead.

I think this is a pretty mundane kind of case—it happens all the time. (There are other kinds of cases with the relevant feature too—imagine a case where one does the wrong thing by refraining from asserting. One may—indeed, ought—to assert, but doesn't.) But I also think it's a counterexample to Rachel McKinnon's 'Supportive Reasons Norm', which she suggests is the central norm governing assertion.

Here is the Supportive Reasons Norm (given on p. 52 of Rachel's recent assertion book):
One may assert that p only if
(i) One has supportive reasons for p,
(ii) The relevant conventional and pragmatic elements of the context are present, and
(iii) One asserts that p at least in part because the assertion that p satisfies (i) and (ii).
My case of Helen is a counterexample because Helen may assert that sloths urinate only once a week, but fails to satisfy condition (iii), since she doesn't make the relevant assertion at all, let alone for a particular reason. In general, that condition will ensure that the permissibility of the assertion entails that the assertion is made. Since it's not true we're only permitted to assert the things we do assert, I don't think condition (iii) is part of a proper characterization of what one may assert. (It is much easier to think something like it may have a role to play in a characterization of when a given assertion is a proper one. Perhaps that's what Rachel had in mind.)