But the larger premise--that intelligent people used to be scattered throughout the class structure, and are now concentrated at the top--is almost impossible to prove, simply because the mass administration of mental tests is such a recent phenomenon.
Smart people are not at the top. 
mnli hypothesis: Smart people are not at the top.  premise: But the larger premise--that intelligent people used to be scattered throughout the class structure, and are now concentrated at the top--is almost impossible to prove, simply because the mass administration of mental tests is such a recent phenomenon.