Irving Kristol's most famous comment was probably that "a neoconservative was a liberal who had been mugged by reality." The obits for Kristol, who passed away yesterday, have tended to focus on his journey across the idelogical spectrum, and thus--like the above comment--invite the reader to speculate on what in fact makes us liberal or conservative. In Barry Gewen's nice New York Times obit, there appears another comment from Kristol, and I think that one's reaction to this remark is probably telling.
Liberalism led to “moral anarchy,” Mr. Kristol said, arguing the point with one of his wisecracking encapsulizations: “In the United States today, the law insists that an 18-year-old girl has the right to public fornication in a pornographic movie--but only if she is paid the minimum wage.”
If you find this witty (and, more importantly, rich with irony) you are probably a conservative. If you find it rather banal, you are probably a liberal.