(a) The plain story: John is in a furniture store. He is looking at a bright red table under normal lighting conditions. He believes the table is red.
Q: Does John know that the table is red?
(b) The more detailed story: John is in a furniture store. He is looking at a bright red table under normal lighting conditions. He believes the table is red. However, a white table under red lighting would look exactly the same to him, and he has not checked whether the lighting is normal, or whether there might be a red spotlight shining on the table.
Q: Does John know that the table is red?
Many epistemologists find it easier to attribute knowledge, rather than mere true belief, to John in case (a) than in case (b),36 despite the fact that, we may suppose, there no difference in
John's epistemic situation between (a) and (b). Case (b) merely draws attention to a counterfactual aspect of John's situation that is unmentioned, but nevertheless present, in case (a). Although many of them regard it as a mistake, something approaching a consensus has emerged amongst epistemologists that we are, as a matter of fact, more reluctant to attribute knowledge when unrealized possibilities of error are mentioned, and so made salient, than we are when such possibilities go unmentioned. For ease of exposition, we will refer to cases like (b) as 'mentioned-error-possibility cases' (hereafter 'MEP-cases'), cases like (a) as 'non MEP- cases', and the phenomenon of interest the 'error-salience phenomenon'.
For some time the existence of the error-salience phenomenon was taken for granted by epistemologists. Recently it has been put to empirical test. Do non-philosophers share philosophers intuitions about MEP and non-MEP cases? Initial studies suggested a negative answer (Buckwalter 2010, Feltz and Zarpentine 2010). More recent studies, however, have found some evidence for the phenomenon. For example, Schaffer and Knobe (2012) presented participants in an experiment with variations on Keith DeRose's (2009) bank cases, in which Hannah asserts to her partner that the bank is open on Saturday. Some participants were given vignettes in which the possibility of error was made salient. Others were given vignettes where this possibility was not made salient. Participants were then asked to rate their degree of agreement or disagreement with the statement: 'Hannah knows that the bank
will be open on Saturday'. Schaffer and Knobe found that participants presented with the non MEP-case were more inclined to agree with the statement than those presented with the MEP- case, to a statistically significant degree. Alexander, Gonnerman, and Waterman (forthcoming) found the same with Nagel's (a) and (b) cases. Further confirmatory work is needed, but from here on in we will assume along with the rest of the participants in the debate of interest that error-salience is a real and robust phenomenon.
The error-salience phenomenon has played an important role in recent debate about the semantics of the word 'knows'. Contextualists hold that the truth conditions of sentences of the form 'S knows that p' are context-sensitive. One popular way of cashing out this idea is that the context partially determines the epistemic standard S needs to meet in order for the sentence 'S knows that p' to be true in that context. Contextualists have claimed to find vindication for their view from the error-salience phenomenon.37 If contextualism is true, it is
perfectly consistent to claim that 'John knows that the table is red' in non MEP-cases like (a) and 'John doesn't know that the table is red' in MEP-cases like (b). The standards required for it to be true to say that 'John knows that the table is red' are higher, the thought goes, in (b) than they are in (a), because an error possibility has been made contextually relevant in (b) but not (a). DeRose (2005) is quite explicit about the error-salience phenomenon being a central motivation for contextualism:
"The best grounds for accepting contextualism concerning knowledge attributions come from how knowledge-attributing (and knowledge-denying) sentences are used in ordinary, non-philosophical talk: What ordinary speakers will count as ‘‘knowledge’’ in some non-philosophical contexts they will deny is such in others" (2005: 172)
By contrast, the error-salience phenomenon seems, prima facie, to pose a challenge to invariantists who hold that 'knows' does not have a contextualist semantics. If the truth- conditions for sentences of the form 'S knows that p' aren't shifty in the way that contextualists suggest, then why are people's knowledge attributions shifty? Invariantism appears to be at odds with actual usage. And this, one might think, is a mark against it. (DeRose 2009, et al.)
Against this background, some invariantists have sort to motivate a certain kind of error-
theory about the error-salience phenomenon. Their strategy is to develop hypotheses about the psychological mechanisms that produce the phenomenon whereby it is the result of well- known heuristics and biases, and then argue that these psychological explanations of the phenomenon show that it does not undermine invariantism. So we see Hawthorne (2004) and Williamson (2005) suggesting that the phenomenon is the result of the influence of the availability heuristic, Nagel (2010) arguing that it is the result of epistemic egocentricity, and Gerken (2013) arguing that it is the result of an epistemic focal bias.
My interest here is not primarily in the debate between invariantists and contextualists (though see §5 for some remarks on the prospects of appealing to psychological explanations to defend classical invariantism). Rather I am first and foremost interested in understanding what psychological mechanisms give rise to the error-salience phenomenon. The proposal put forward here is that the influence of the simulation heuristic might at least partially explain it. In the next section I introduce the heuristic and make the case for its ability to explain the phenomenon.