Formal and Informal Language

Paul Ricoeur suggested that more formal kinds of explanation and informal understanding are related to one another by the first playing a mediating role in the second, and used this in a very nice reconciliation of Aristotelian and Kantian ethics. From the formal side, the mathematician Haskell Curry — whose work has greatly influenced the theory of programming languages — argued in the 1950s that the ultimate metalanguage for all formal languages can only be ordinary natural language. Amid the tremendously rich development of formal languages in the 20th century, this point got somewhat lost, but more recently Robert Brandom’s expansion of Wilfrid Sellars’ work on material inference has provided a detailed account of how this works. The circumscribing role of informal natural language in all formal developments is related to the great Kantian insight of the primacy of practical over theoretical reason.