As the editor of this volume notes, "One great benefit of these lectures is that they reveal how Rawls conceived of the history of the social contract tradition, and suggest how he saw his own work in relation to that of Locke, Rousseau, and Kant, and to some degree Hobbes as well" (pg. x). Rawls was reluctant to publish these lectures: "It was only after he was prevailed upon to publish his 'Lectures on the History of Moral Philosophy'...that he agreed to allow his lectures on the history of political philosophy to be published as well" (pg. xv).
Rawls says his goal in these lectures is to "try to identify the more central features of liberalism as expressing a political conception of justice when liberalism is viewed from within the tradition of democratic constitutionalism. One strand in this tradition, the doctrine of the social contract, is represented by Hobbes, Locke, and Rousseau; another strand, that of utilitarianism, is represented by Hume and J.S. Mill; whereas the socialist, or social democratic strand, is represented by Marx, whom I consider largely as a critic of liberalism" (pg. xvii). Rawls goes on to admit that his approach "do[es] not present a balanced introduction to the political and social philosophy" (pg. xviii).
The "Lectures on the History of Political Philosophy" are, more specifically, a history of modern contractual political philosophy. These lectures will provide added clarity to the tensions between his book A Theory of Justice and his Justice as Fairness: A Restatement. For example, Michael Sandel's, whose appraisal of Rawls works mostly off of "A Theory of Justice" alone, wrote in his book Liberalism and the Limits of Justice that Rawls offers "deontology with a Humean face" which entails, according to Sandel, that Rawls doctrine "justice is the first virtue of social institutions" a teleology based an a metaphysical notion of the self which is the exact thing Rawls wanted to avoid; Sandel says, "teleology to the contrary, what is most essential to our personhood is not the ends we choose but our capacity to choose them. And this capacity is located in a self which must be prior to the ends it chooses." Thus Sandel takes offense against Rawls' Kantian style distinctions like "original position," behind a "veil of ignorance."
However, with "Justice as Fairness" and other writings (e.g. Kantian Constructivism) Rawls became more clear that there is no noncircular argument for democratic ideas; he says in "Justice as Fairness: A Restatement," that, "since justice as fairness is intended as a political conception of justice as a democratic society, it tries to draw solely upon basic intuitive ideas that are embedded in the political institutions of a democratic society and the public traditions of their interpretation."
Rawls shows in these lectures on the history of philosophy how his philosophy is sufficiently historical and contingent to avoid much overworked metaphysics: "the same effect as that of a veil of ignorance may result from a combination of other elements. Thus, rather than exclude information, we can allow people to know whatever they now know and yet make the contract binding in perpetuity and suppose the parties to care about their descendants, indefinitely into the distant future. In protecting their descendent's as well as themselves, they face a situation of great uncertainty. Thus, roughly the same arguments, somewhat modified, pertain as with a thick veil of ignorance" (pg. 19; see also footnote 7 pg, 269).
These lectures, however, are not so much about Rawls' theory of justice. Rawls writes charitably about others throughout, when he does criticize it is insightful. These lecture notes are surprisingly detailed at times, with footnotes and full citations. A benefit for researchers will be the generous index at the book's end.