In his 1905 philosophical analysis of humor, Jokes and Their Relation to the Unconscious, Sigmund Freud cites a classic Jewish joke: “Two Jews met in a railway carriage at a station in Galicia. ‘Where are you going?’ asked one. ‘To Cracow,’ was the answer. ‘What a liar you are!’ broke out the other. ‘If you say you’re going to Cracow, you want me to believe you’re going to Lemberg. But I know that in fact you’re going to Cracow. So why are you lying to me?’”
On the surface, the joke is a self-deprecating jab at the Jewish tendency to overthink things. But on a deeper level (and for Freud of course there is always a deeper level) the joke comments on the difficulty of discerning truth. He asks, “is it the truth if we describe things as they are without troubling to consider how our hearer will understand what we say?” Freud proposes that jokes like the one above “attack not a person or an institution but the certainty of our knowledge itself.” He is struck by how many jokes of this nature are Jewish ones.