 For Russell, the logicism project originated from the dream of a rock-solid mathematics, no longer governed by Kantian intuition, but by logical rigor. Hence, the discovery of a devastating paradox—later called ‘Russell’s paradox’—at the heart of mathematical logic was a serious blow for Russell, and kicked off his search for a theory to prevent paradox. He actually came up with several theories, but retained the ramified theory of types in Principia Mathematica. Moreover, the ‘logicizing’ of arithmetic required extra-logical patchwork: the axioms of reducibility, infinity, and choice. None of this patchwork could ultimately satisfy Russell. His original dream evaporated and, looking back later in life, he wrote: “The splendid certainty which I had always hoped to find in mathematics was lost in a bewildering maze” (1959: 157).