What Liars Can Tell Us About the Knowledge Norm of Practical Reasoning

Abstract

If knowledge is the norm of practical reasoning, then we should be able to alter people's behavior by affecting their knowledge as well as by affecting their beliefs. Thus, as Roy Sorensen (2010) suggests, we should expect to find people telling lies that target knowledge rather than just lies that target beliefs. In this paper, however, I argue that Sorensen's discovery of “knowledge‐lies” does not support the claim that knowledge is the norm of practical reasoning. First, I use a Bayesian framework to show that in each of Sorensen's examples, knowledge‐lies alter people's behavior by affecting their beliefs. Second, I show that while we can imagine lies that target knowledge without targeting beliefs, they cannot alter people's behavior. In other words, knowledge‐lies actually work (i.e., manipulate behavior) by targeting beliefs or they do not work at all.

Lying as a scalar phenomenon

“…The picture is complex: as Bazzanella (2009: 78) points out, "the different degrees of intensity in lying result from the complex interplay of various layers and parameters". Some philosophers (Chisholm & Feehan 1977;Fallis 2011;Staffel 2011) contend that the intention to deceive, as well as the effects of deception, can be graded. Several pragmatic parameters determinant for lying also have scalar features, such as relevance (Wilson & Sperber 2002;Van der Henst et al 2002), felicity, and the relations between the interactants (like social relations, and respective trust) (Bazzanella 2009).…”

Can You Lie Without Intending to Deceive?

“…Finally, according to Sorensen (), a knowledge‐lie is a statement intended to block knowledge that the very statement is false but which is not meant to convince the hearer that it is true. Sorensen's proposal is contentions and has quickly attracted strong challenges contesting both his conception and the examples that he offers (Fallis ; Staffel , forthcoming; Lackey ). I discuss knowledge‐lies and propose a novel account elsewhere (Krstić ) .…”

Knowledge‐lies re‐examined

“…With their lies, Sorensen (, p. 608) argues, they are preventing Crassus from learning who Spartacus is; but, excluding Antoninus, none of them intends to deceive him about who they are. Furthermore, again excluding Antoninus, each slave intends to prevent Crassus from knowing that his assertion ‘I am Spartacus!’ is untrue (one of the captured slaves really is Spartacus), but not to make Crassus believe that he (i.e., the slave asserting ‘I am Spartacus!’) is Spartacus (see Fallis, , p. 359, n. 32; Staffel, forthcoming).…”

“…According to Sorensen (, p. 610) ‘an assertion that p is a knowledge‐lie exactly if [it is] intended to prevent the addressee from knowing that p is untrue but is not intended to deceive the addressee into believing p .’ That is to say, a knowledge‐lie is a statement intended to block knowledge that that very statement is false (Fallis, , p. 362). Sorensen argues that the slaves did not intend to make Crassus believe what they asserted and that thus none of them intended to deceive the general – intending to deceive, Sorensen takes it (also, Mahon, ; Carson, , pp.…”