Take the issue of federal spending, for example. During FDR's presidency, the federal government grew exponentially in size. The federal government usurped traditional state power; it regulated minute details of Americans' everyday lives. The American governmental structure changed fundamentally -- yet no constitutional amendment justified that change. Instead, FDR claimed authority in the original text of the Constitution. The American people never had to face the fact that by approving FDR's program, they were altering the Constitution. FDR never had to face the political fallout of altering the Constitution.
Whether or not Americans acknowledged FDR's change, however, the change occurred. The constitutional structure fell out of kilter; federal power overrode state power, removing one of the key checks and balances designed to satisfy local communities and prevent federal dominance.
Would FDR's program have passed if he had proposed a constitutional amendment? Perhaps. But at least Americans would have recognized the sea change they were approving. Such recognition provides accountability -- it requires politicians to justify changing the greatest founding text ever written.
Whether or not Dr. Sabato's proposed amendments solve the problems of governance, his call for a new Constitutional Convention is an important one. To solve the problems of governance, we must stop pretending that the Constitution is all things to all people -- we must decide whether it ought to be challenged, and if so, where. The Founding Fathers would expect any proposed major governmental change to face up to the historic challenge.