From Discursive Practice to Logic? Remarks on Logical Expressivism

This paper investigates Robert Brandom's programme of logical expressivism and in the process attempts to clarify his use of the term practice, by means of a comparison with the works of sociologist and anthropologist Pierre Bourdieu. The key claim of logical expressivisim is the idea that logical terms serve to make explicit the inferential relations between statements which already hold implicitly in a discursive practice that lacks such terms in its vocabulary. Along with this, it is claimed that the formal validity of an argument is derivative on so-called material inference, in that an inference is taken to be logically valid only if it is a materially good inference and cannot be made into a bad inference by substituting nonlogical for nonlogical vocabulary in its premises and conclusion. We note that no systematic account of logical validity employing this substitutional method has been offered to date; rather, proposals by e.g. Lance and Kremer, Piwek, Kibble and Brandom himself have followed the more conventional path of developing a formally defined system which is informally associated with natural language examples. We suggest a number of refinements to Brandom’s account of conditionals and of validity, supported by analysis of linguistic examples including material from the SNLI and MultiNLI corpora and a review of relevant literature. The analysis suggests that Brandom’s expressivist programme faces formidable challenges once exposed to a wide range of linguistic data, and may not in fact be realisable owing to the pervasive context-dependence of linguistic expressions, including 'logical' vocabulary. A further claim of this paper is that a purely assertional practice may not provide an adequate basis for conditional reasoning, but that a more promising route is provided by the introduction of imperatives, as in so-called "pseudo-imperatives" such as "Get individuals to invest their time and the funding will follow". We conclude the resulting dialogical analysis of conditional reasoning is faithful to Brandom's Sellarsian intuition of linguistic practice as a game of giving and asking for reasons, and conjecture that language is best analysed not as a system of rules but as a Wittgensteinian repertoire of evolving micro-practices.