Bridge principles and combined reasoning

Abstract

Hume's well-known objection on the purported connections between 'is' and 'ought' in philosophical argumentation gave rise to a quarrel about the legitimacy of statements that bind factualities to norms. The idea of bridge principle has been inaugurated as statements which precisely crystallize principles of mixed reasoning. We critically examine the role of bridge principles within the context of combination of logics, emphasizing situations where such principles spontaneously arise with desirable and undesirable consequences for combined reasoning.