So, to clarify the matter to himself, he asks whether he would buy if he knew that the Democratic candidate were going to win, and decides that he would.
[2] Richard Jeffrey[2] and later Judea Pearl[3] showed that Savage's principle is only valid when the probability of the event considered (e.g., the winner of the election) is unaffected by the action (buying the property).
Blyth constructed a counterexample to the sure-thing principle using sequential sampling in the context of Simpson's paradox,[4] but this example violates the required action-independence provision.
However the formal definition of the principle, known as P2, does not involve knowledge because, in Savage's words, "it would introduce new undefined technical terms referring to knowledge and possibility that would render it mathematically useless without still more postulates governing these terms."
It is similarly targeted by the Ellsberg and Allais paradoxes, in which actual people's choices seem to violate this principle.