That quote comes from Deirdre McCloskey's Bourgeois Virtues and expresses in my mind the critical importance for political and social philosophy to be grounded in economics and economic history. McCloskey reiterates this point in her contribution to the symposium on John Tomasi's Free Market Fairness at BHL. Abstract discussions of "just" worlds, must be constrained by an institutional analysis of how we imperfect humans living in an imperfect world can nevertheless find ways to live better together. As McCloskey points out in her contribution at BHL as well as more fully in Bouregois Virtues, the meta-narrative of high liberalism is a false narrative. In fact, countering this meta-narrative was the point of my own first post over at BHL.
McCloskey is always a joy to read, and this contribution to the symposium is no exception. Put simply, the meta-narrative of high liberalism is wrong because the factual background assumed in the narrative is factually inaccurate. But you would only know that if you bothered to study seriously economics and economic history. Thus, perhaps the best remedy to the intellectual ills of high liberalism is to insist on the point made in the quote from McCloskey -- "We can't do with philosophical definition a job that needs to be done with factual inquiry."