Julia Staffel

This paper investigates the relationship between two evaluative claims about agents’ de- grees of belief: (i) that it is better to have more, rather than less accurate degrees of belief, and (ii) that it is better to have less, rather than more probabilistically incoherent degrees of belief. We show that, for suitable combinations of inaccuracy measures and incoherence measures, both claims are compatible, although not equivalent; moreover, certain ways of becoming less incoherent always guarantee improvements in accuracy. Incompatibilities between particular incoherence and inaccuracy measures can be exploited to argue against particular ways of measuring either inaccuracy or incoherence.

Sorensen offers the following definition of a ‘knowledge-lie’: ‘An assertion that p is a knowledge-lie exactly if intended to prevent the addressee from knowing that p is untrue but is not intended to deceive the addressee into believing p.’ According to Sorensen, knowledge-lies are not meant to deceive their addressee, and this fact is supposed to make them less bad than ordinary lies. I will argue that standard cases of knowledge-lies, including almost all the cases Sorensen considers, do in fact involve deception, contrary to what Sorensen claims. And while there are cases of non-deceptive knowledge-lies, such cases are deviant, either because it is only incidental that the knowledge-preventing assertion is a lie, or because it is only incidental that the lie doesn't deceive. Here's an example of a knowledge-lie: Dr Head is considering firing Dr Appendix because of his weak research. But he doesn't want to fire Appendix unless he knows that Appendix's research isn't good, and so he consults Dr Heart. Head knows that if Appendix's research is good, then Heart will tell the truth and say so, whereas if Appendix's work isn't good, then Heart may or may not …

In this paper I am concerned with the question of whether degrees of belief can figure in reasoning processes that are executed by humans. It is generally accepted that outright beliefs and intentions can be part of reasoning processes, but the role of degrees of belief remains unclear. The literature on subjective Bayesianism, which seems to be the natural place to look for discussions of the role of degrees of belief in reasoning, does not address the question of whether degrees of belief play a role in real agents’ reasoning processes. On the other hand, the philosophical literature on reasoning, which relies much less heavily on idealizing assumptions about reasoners than Bayesianism, is almost exclusively concerned with outright belief. One possible explanation for why no philosopher has yet developed an account of reasoning with degrees of belief is that reasoning with degrees of belief is not possible for humans. In this paper, I will consider three arguments for this claim. I will show why these arguments are flawed, and conclude that, at least as far as these arguments are concerned, it seems like there is no good reason why the topic of reasoning with degrees of belief has received so little attention