ABSTRACT
Contextualism is the view that knowledge ascriptions – utterances of sentences containing the word “knows” – express different propositions in different contexts of utterance. Consider these examples:
low: Hannah and Sarah are discussing whether the bank is open on Saturdays. Hannah recalls it was open on a previous Saturday. She says, “I know that the bank is open on Saturdays.” Sarah agrees.
high: Laura and Sarah are discussing whether the same bank is open on Saturdays. Sarah says, “Hannah has been in there on Saturday before.” But Laura replies, “Banks can change their opening hours. Hannah doesn’t know that the bank is open.” Sarah agrees. 1
Assume the bank is open. The thought is that Hannah’s knowledge ascription and Laura’s knowledge denial are both true, even though we can specify that Hannah’s epistemic position is the same in both cases (for dissent, see Brown 2006; Nagel 2008; Rysiew 2001). The contextualist explanation is that their respective uses of “knows” have different semantic values. 2 Let’s say that an utterance of “S knows that p” is true in a context c iff S’s evidence rules out all of the alternatives in which not-p that are relevant in c, where different sets of alternatives are relevant in different contexts (see Blome-Tillmann 2014; Ichikawa 2011; Lewis 1996). 3 The alternative in which the bank has changed its opening hours is relevant in high (Laura and Sarah take it seriously), but isn’t relevant in low (Hannah and Sarah don’t consider it). So Hannah’s use of “knows” refers to a property the possession of which would allow Hannah to rule out one set of alternatives, whereas Laura’s use of “knows” refers to a property the possession of which would allow Hannah to rule out another set. Because (let’s assume) Hannah has the former property but not the latter, Hannah’s knowledge ascription is true, whereas Laura’s is false. 4