"But the NYT chose a neo-Marxist rather than liberal path to make a very specific claim: that slavery is not one of many things that describe America’s founding and culture, it is the definitive one." Well, the author does know what liberalism is, but definitely does not know what Marxism is!<p>Marxism does have a good answer to the original question of the piece: "How can an enduring “ideal” — like, say, freedom or equality — be “false” at one point in history and true in another?" - Marxists argue that ideas can be progressive at one time, and become reactionary at a later stage of history. Ideas do not determine history, but are in general a reflection of class forces. When capitalism was progressive, in the founding days of the country, the ideas that upheld the system of private ownership were progressive ideas! The forces these ideas represent helped defeat monarchies and slavery. Today, advocates of the free market play the opposite role, of holding society back, because capitalism is in a deep crisis and socialism has become socially and technologically possible.