Jack Trotter on 'The fall of a monument to states' rights', at Chronicles.
"Calhoun’s Disquisition is a dense and brilliantly argued thesis on the foundations of constitutional government. Slavery is mentioned in passing only once. At its heart is the view that if we locate the voice of the people only in numerical majorities, we are already well down the road to tyranny. Thus, he offered the concept of the 'concurrent majority'—that is, a majority achieved through the conflict of interests between the various parts of the national community. Such a majority would not result in perfect harmony, but in a reasonable compromise, in which the interests of all the conflicting parties are truly represented. Calhoun made no attempt to disguise the reality of power. 'Power,' he wrote, 'can only be resisted by power.' And the vehicle of that resistance can only be sovereign states."
See Calhoun, "The Concurrent Majority" from A Disquisition on Goverment, in Gateway to the Great Books (10 Vol., 1963) volume 7