Ponnuru and Lowry have responded to critics of their American Exceptionalism piece, I see. I’ll just quote a bit from the end:

Victor Davis Hanson notes that one reason for American exceptionalism may be that we did not inherit from England “a large underclass of only quasi-free people attached to barons as serfs.” Sadly, a worse institution took root here, but never became part of the national psyche.

Thank goodness it never became a serious problem. It might have left scars.