On the Composition of Principia Mathematica
They came to the supper table after a fruitless afternoon to find there Patrick Sarsfield, 1st Earl of Lucan, deceased 212 years previous but sitting before them nonetheless alive and smartly dressed.
On a fine June morning in 1906 Bertrand and Alfred breakfasted together, cleared the table, and began to write their Principia. Or tried to begin. But nothing came and so they went for a walk to talk and get things moving. Nothing came on the walk either, so they decided to spend the afternoon working separately and to compare notes at supper. Again, nothing came.
It went on like this for three weeks of growing despair and anxiety until July 12, the 215th anniversary of the defeat of the Jacobite army in the Battle of Aughrim, when they came to the supper table after a fruitless afternoon to find there Patrick Sarsfield, 1st Earl of Lucan, deceased 212 years previous but sitting before them nonetheless alive and smartly dressed. What ought a pair of English philosophers to do with a Jacobite ghost? Sit down! They sat.
The Right Honorable Sarsfield did not speak to the writers-block afflicted philosophical supper pals. In silence he handed them the top sheet from the small pile before him, which contained this:
And so it went for many weeks. Russell and Whitehead tried to write together. And failed. Tried to write separately. And failed. And having made the attempts and accepted the failures, they would reconvene to sup, and the Jacobite ghost would produce a new stack of pages attempting to establish a logical foundation for mathematics. And the stacks of pages continued until conclusion: “The paradoxes rest on the confusion between factual and assertive propositions.”1 Then Patrick Sarsfield, 1st Earl of Lucan, returned to the grave to await the resurrection of the dead and the life of the age to come, and A.N. Whitehead and Bertrand Russell published Principia Mathematica under their own names. They never spoke of the ghost to anyone, not even to each other, and neither read more than a few pages of the Principia. But vivid dreams of the Jacobite defeat at Aughrim haunted both men for the rest of their days.
If you don’t see the joke in this sentence, you can thank or blame your Logic teachers—you had some, didn’t you?—for never introducing you to the Mystical Path of the Logicians and its comedic double. Cf. Machiavelli’s concept verità effettuale and its antecedent, Dante’s veritates occultas et utiles.