The Logical System of Frege's Grundgesetze: A Rational Reconstruction

Accepted for pubblication and forthcoming in Manuscrito; This paper aims at clarifying the nature of Frege's system of logic, as presented in the first volume of the Grundgesetze. We undertake a rational reconstruction of this system, by distinguishing its propositional and predicate fragments. This allows us to emphasise the differences and similarities between this system and a modern system of classical second-order logic.