Surprise Paradox

Joachim Breitner 🌐

July 17, 2016

This is a development version of this entry. It might change over time and is not stable. Please refer to release versions for citations.


In 1964, Fitch showed that the paradox of the surprise hanging can be resolved by showing that the judge’s verdict is inconsistent. His formalization builds on Gödel’s coding of provability. In this theory, we reproduce his proof in Isabelle, building on Paulson’s formalisation of Gödel’s incompleteness theorems.


BSD License


Session Surprise_Paradox