Joe Salerno

The paradox of knowability is a logical result suggesting that, necessarily, if all truths are knowable in principle then all truths are in fact known. The contrapositive of the result says, necessarily, if in fact there is an unknown truth, then there is a truth that couldn't possibly be known. More specifically, if p is a truth that is never known then it is unknowable that p is a truth that is never known. The proof has been used to argue against versions of anti-realism committed to the thesis that all truths are knowable. For clearly there are unknown truths; individually and collectively we are non-omniscient. So, by the main result, it is false that all truths are knowable. The result has also been used to draw more general lessons about the limits of human knowledge. Still others have taken the proof to be fallacious, since it collapses an apparently moderate brand of anti-realism into an obviously implausible and naive idealism.

Lewis/Stalnaker semantics has it that all counterpossibles (i.e., counterfactual conditionals with impossible antecedents) are vacuously true. Non-vacuism, by contrast, says the truth-values of counterpossibles are affected by the truth-values of the consequents. Some counterpossibles are true, some false. Williamson objects to non-vacuism. He asks us to consider someone who answered ‘11’ to ‘What is 5 + 7?’ but who mistakenly believes that he answered ‘13’. For the non-vacuist, (1) is false, (2) true: (1) If 5 + 7 were 13, x would have got that sum right (2) If 5 + 7 were 13, x would have got that sum wrong Williamson is not persuaded by the initial intuitiveness of such examples: ... they tend to fall apart when thought through. For example, if 5 + 7 were 13 then 5 + 6 would be 12, and so (by another eleven steps) 0 would be 1, so if the number of right answers I gave were 0, the number of right answers I gave would be 1. (2006) That’s the whole argument—much of it implicit. Alan Baker’s critique (2007) of Brogaard and Salerno (2007) prompts us to say something less abbreviated about a less abbreviated form of Wiliamson’s argument. Then we further develop our (2007) counterfactual analysis of essense

At the center of the debate between contextualist versus relativist semantics for epistemic modal claims is an empirical question about when competent subjects judge epistemic modal disagreement to be present. John MacFarlane’s relativist claims that we judge there to be epistemic modal disagreement across the widest range of cases. We wish to dispute the robustness of his data with the results of two studies. Our primary conclusion is that the actual disagreement data is not consistent with relativist predictions, and so, that the primary motivation for relativism disappears. Our study differs from a related study by Knobe and Yalcin :1–21, 2014) in that we focus directly on the question of genuine disagreement, as opposed to a question about truth or the appropriateness of retraction. Some of our findings agree with theirs about relativism. We uncover new lessons along the way, including that there are widespread situation effects of epistemic modal discourse; idiosyncratic features of the vignettes significantly influencing judgments about epistemic modal disagreement. We reflect with mixed feelings on the prospects for contextualism to accommodate our findings.

In his presidential address to the APA, Alvin Plantinga argues that the only sensible way to be an anti-realist is to be a theist. Anti-realism (AR) in this context is the epistemic analysis of truth that says, "(AR) necessarily, a statement is true if and only if it would be believed by an ideally [or sufficiently] rational agent/community in ideal [or sufficiently good] epistemic circumstances." Plantinga demonstrates, with modest modal resources, that AR entails that necessarily, ideal epistemic circumstances obtain. As it is a contingent matter whether ideal epistemic circumstances obtain, Plantinga concludes that an anti-realist should be a theist. In this paper, we show that counterfactual analyses of truth as epistemic are instances of a more general problem of philosophical analysis. More specifically, without a radical revision of the logic, counterfactual analyses of truth as epistemic cannot avoid perpetrating some version of the conditional fallacy. Even so, we argue, anti-realists are not committed to the necessary existence of ideal epistemic circumstances and therefore need not be theists.