Synechepedia

Notes on Girard’s The Blind Spot

Martin-Löf, Per, & Sambin, G., Intuitionistic type theory (1984), : Bibliopolis Napoli.

Reconciling Formal Foundations with the Infinite

The core problematic addressed in the work, that which intuitionistic type theory (ITT) is meant to be an answer to, is that of raising a firm formal foundation of mathematical reasoning which is consistent, complete over it’s domain, and capable of grounding reasoning over infinite domains.

Putting Form and Meaning Together

We will avoid keeping form and meaning (content) apart. Instead we will at the same time display certain forms of judgment and inference that re used in mathematical proofs and explain them semantically. Thus we make explicit what is usually implicitly taken for granted. When one treats logic as any other branch of mathematics, as in the metamathematical tradition originated by Hilbert, such judgments and inferences are only partially and formally represented in the so-called object language, while they are implicitly used, as in any other branch of mathematics, in the so-called metalanguage.

This practice of developing the meanings and use of judgment at the same time, expecting the one to inform the other through the process of the exposition and use is familiar and essential to the continental philosophical tradition.