Andrew Peet

According to standard assumptions in semantics, ordinary users of a language have implicit beliefs about the truth-conditions of sentences in that language, and they often agree on those beliefs. For example, it is assumed that if Anna and John are both competent users of English and the former utters ‘grass is green’ in conversation with the latter, they will both believe that that sentence is true if and only if grass is green. These assumptions play an important role in an intuitively compelling picture of communication, according to which successful communication through literal assertoric utterances is normally effected thanks to our shared beliefs about the truth-conditions of the sentences uttered in the course of the conversation. Against these standard assumptions, this paper argues that the participants in a conversation rarely have the same beliefs about the truth-conditions of the sentences involved in a linguistic interaction. More precisely, it argues for Variance, the thesis that nearly every utterance is such that there is no proposition which more than one language user believes to be that utterance’s truth-conditional content. If Variance is true, we must reject the standard picture of communication. Towards the end of the paper I identify three ways in which ordinary conversations can be communication-like despite the truth of Variance and argue that the most natural amendments to the standard picture fail to explain them.

Most work in the epistemology of testimony is built upon a simple model of communication according to which, when the speaker asserts that p, the hearer must recover this very content, p. In this paper, I argue that this ‘Content Preservation Model’ of communication cannot bear the weight placed on it by contemporary work on testimony. It is popularly thought that testimonial exchanges are often successful such that we gain a great deal of knowledge through testimony. In addition, the testimonial knowledge so gained is thought to be informative: it closes off epistemic possibilities for the agent. However, in the literature on truth-conditional content, there is no theory of content that can underpin both of these commitments simultaneously if the Content Preservation Model is true. There is a minimal notion of content, which is commonly preserved in communication, but which is typically uninformative; there is a maximal notion of content, which is often informative, but which is not often preserved in communication; and, although there are moderate positions between these two extremes, these views cannot strike the right balance between informativeness and shareability. Thus, an epistemology of testimony that endorses the Content Preservation Model faces a dilemma: on the first horn, testimonial exchanges are rarely successful; on the second horn, testimonial content is rarely informative. I suggest that this dilemma motivates further exploration of alternative communicative foundations for the epistemology of testimony.

I argue for the Cooperative Warrant Thesis (CWT), according to which the determinants of testimonial contents in communication are given by the practical requirements of cooperative action. This thesis distances itself from conventionalist views, according to which testimony must be strictly bounded by conventions of speech. CWT proves explanatorily better than conventionalism on several accounts. It offers a principled and accurate criterion to distinguish between testimonial and non-testimonial communication. In being goal-sensitive, this criterion captures the role of weak and robust cooperation in determining the contents to which speakers testify or fail to testify. And, finally, it yields a principled explanation of why testimony entails the epistemic commitments that distinguish it as an epistemic source.