Events from 1931

Kurt Gödel publishes his Incompleteness Theorems, proving that any consistent formal system containing arithmetic is incomplete

John Childs (Columbia Teachers College): '[We] reject completely the hypothesis of choice. We consider the traditional doctrine of free-will to be untenable'

Pope Pius XI: 'Religious socialism, Christian socialism, are contradictory terms; no one can be at the same time a good Catholic and a true socialist'

CPUSA surveys American churches, finding 50 million church members and significant wealth

IBM introduces Type 600 series multiplying punch - first machine to perform multiplication automatically

von Neumann provides rigorous mathematical foundations for quantum mechanics

George David Birkhoff proves ergodic theorem - time average equals space average

DIVINE MERCY VISION TO ST. FAUSTINA - Jesus appears with red and white rays from heart - 'Paint an image according to what you see'

Pope Pius XI issues 'Quadragesimo Anno' on 40th anniversary of Rerum Novarum

Pope Pius XI declares St. Robert Bellarmine Doctor of the Church - defender of papal authority