Cerber is--rightly, I think--a little dubious regarding what appears to be Whittington’s "official" thesis--that Presidents have "always sought to pick justices who would, by the president’s lights, get the Constitution right." This surely underestimates the political considerations that have in part motivated some nominations. But by keeping our eye on the central responsibility of the judiciary and on the way in which Presidents should respect that role in their own choices, Whittington does us a service. Whatever roles "diversity" and "balance" may have in legislatures and in the choices made by individual voters, they ought to have no role in judicial nominations. We ought to want a Supreme Court that looks at the Constitution, rather than one that looks like America.
Update: Gerard Bradley has more, almost all of it much smarter than anything I said.