The Scottish Philosophy is no longer in good repute despite its proud reign in another day. Indeed, few, if any, schools of philosophy have been given such disdainful treatment by historians as Common Sense Realism; and few, if any, philosophers have had to suffer such ignominious re-evaluations as Thomas Reid and Dugald Stewart, who were once lionized as the founders of a great and enduring philosophical synthesis. Yet the very decisiveness of this reversal creates at least two challenging problems, one philosophical and the other historical. First, was the Scottish Philosophy as undistinguished as posterity has judged it to be? (To this I would answer with a qualified negative, but the subject is outside the purview of the present essay.) Second, why, when its ultimate rejection was so complete, did the Scottish Philosophy for over a century play such a large and variegated role in Western thought, being in its origins a forceful liberalizing religious movement, in France the near-official “middle-way” of the Restoration and July Monarchy, and in America the handmaiden of both Unitarianism and Orthodoxy? The account which follows is directed to this second question as well as to the factors in Scottish and American intellectual history which demonstrate the importance of asking it.