- (philosophy) the proposition that the universe began to exist last Thursday, with the appearance of age and history
- 2007 December 15, Donald R. Prothero, “The Nature of Science”, in Evolution: what the fossils say and why it matters, New York: Columbia University Press, →ISBN, page 9:
- Any memories you might have of the past were created in your head when you were created, just as the fossils were placed in the rocks to look as if they were from the ancient past. This idea is nicknamed “Last Thursdayism” by the famous philosopher Bertrand Russell as in “the world might have been created last Thursday—how would we know the difference?”
- 2009, William Powell, “Creation Theology”, in Philosophy of Scientific Creationism, New Delhi: Global Vision Publishing House, page 224:
- Last Thursdayism is a response to omphalism which posits that, by the same logic, the world might have been created last Thursday (or, by implication, any given date and time), but with the appearance of age: people's memories, history books, fossils, light already on the way from distant stars, and so forth.
Used as a response to claims of young-earth creationism that the Earth was created to look old, that, by the same logic, the world might have begun last Thursday.