In 1885, Paul Gauguin abandoned his wife and five children to pursue painting, later moving to the south seas to realise his dream. The resulting works—on display from the end of September at Tate Modern—are stunning. But does their beauty mean that Gauguin’s decision is less blameworthy than if he had left his family and then failed as a painter?

The philosopher Bernard Williams used a fictionalised version of Gauguin’s life to illustrate what he called “moral luck”: the idea that the way things turn out can affect their moral worth. Gauguin left his family in penury in the hope that he would become a great artist. He could not, Williams points out, have been sure this move would pay off. The only thing that could justify his decision was success itself, a justification that inexorably entailed luck.

Immanuel Kant would have considered “moral luck” an oxymoron. Kant insisted that