The epistemic pragmatics of presupposition effects
Authors:   , Müller Misha 
Published: March 2024

This thesis is devoted to the processing and accommodation of presuppositions in the light of Relevance theory. I emphasize from the start that presuppositions were left aside early on by Relevance theory and need to be reintegrated into the theory, in the light of recent, often major, contributions from this tradition. The first part outlines the different categories of presuppositions considered, ranging from semantic presuppositions to discursive presuppositions. With regard to semantic presuppositions, I present the main approaches and debates, highlighting the problem of the extreme heterogeneity of this category. As for discursive presuppositions, I provide specific identification criteria for this pragmatic category and identify three distinct levels in which this category is involved: first-order presuppositions being background inferences in the absence of encyclopedic knowledge about concepts, second-order being background inferences based on encyclopedic knowledge about concepts, and third-order being background inferences relating to social hierarchies which enable a specific speech act. The second part argues that semantic and discursive presuppositions can be conceived as a homogeneous category once their pragmatic effects are closely examined. First, I argue that both semantic and pragmatic presuppositions are triggered by the presumption of relevance that each utterance communicates. While processing the foreground content of an utterance, the addressee enriches the meaning by building hypotheses about the reasons that motivate the utterance. Furthermore, I argue that presupposition effects are relatively less ostensive meanings that need to be taken into account by adding a third dimension to Sperber and Wilson’s (2015) diagram. Subsequently, I address the epistemic effects of presupposition accommodation. Building on the seminal work of Sperber et al. (2010) on Epistemic Vigilance, I reconsider presuppositions from a developmental perspective. I argue that presuppositions are "primary inferences", relevant to the acquisition of knowledge about the world, but that they are gradually relayed to the conversational background. Returning to presuppositions in adult populations, I argue that they contribute more to the acceptance of an utterance than to its comprehension, highlighting the many cases where the addressee encounters no difficulty in interpreting the utterance when the presupposition turns out to be lacking a referent or even to be false. However, I point out the paradox that such an approach raises when paying attention to the epistemic errors made in famous cognitive illusions, such as the Moses Illusion. Indeed, several experiments in psychology have shown that in some cases the addressee accepts an utterance as relevant while overlooking an obvious error. The third part addresses specifically the problem of accepting verbal contents that contain an obviously false presupposition. I present various approaches that have attributed to presuppositions a highly persuasive or manipulative power, either because they would allow for plausible deniability or because they would force the incorporation of new beliefs in an unconscious way. I highlight the limitations of these approaches, discussing numerous counterexamples, as well as experimental data that portray the phenomenon in a more nuanced way. Finally, I distinguish three types of accommodation, namely a) conscious accommodations, b) unconscious accommodations with epistemic effects and c) unconscious accommodations without epistemic effects. To conclude, I suggest a way of resolving the contradiction raised by the acceptance of obviously false presuppositions for the addressee's epistemic vigilance: first, drawing on the distinctions made between different types of accommodation, I point out that only a subset of them raise a problem for the addressee's epistemic vigilance, namely “unconscious accommodation with epistemic effects”. Secondly, I emphasize the optimal – and therefore imperfect – nature of processes dedicated to the verification of information. This allows us to reconcile the idea that humans accommodate false information despite their epistemic vigilance.