In a series of recent papers and a book, Warren (2015a-c, 2016, 2017, 2018, 2020) has offered an extensive defence of logical conventionalism. Warren (2020) expresses sympathy for deflationism about truth and suggests that deflationism and logical conventionalism should be combined for semantic and metasemantic theorizing. Against this view, I argue that logical conventionalism and deflationism are difficult to combine, and may even be incompatible. I first identify disquotationalism as the most attractive form of deflationism from a conventionalist point of view. Disquotationalism however takes the notion of truth to be exhausted in the first instance by the T-schema as relativized to a speaker’s own language. Truth ascriptions to sentences of alien languages must be based on translation or incorporation of those sentences into the speaker’s own language. Logical conventionalism, for various reasons, requires that we ascribe truth to sentences based on logics alien to our own. I argue that the deflationist’s methods of translation and incorporation are insufficient for this task. Incorporation fails due to well-known collapse results. Translation fails since different logics are not in general intertranslatable. Therefore, deflationism and logical conventionalism are difficult to reconcile. The paper concludes by arguing that the same problem arises even on a minimalist version of deflationism.
