Rawls was a great admirer of John Locke (1632–1704). He admired Locke the thinker as one of the seminal figures in the social contract tradition. But Rawls admired Locke the person perhaps even more. At various points Rawls called him a truly great person. He commended Locke for his loyalty to the Earl of Shaftesbury, and especially for the “enormous risks to his life” he took in defense of constitutional government against royal absolutism. Locke, as Rawls tellingly put it, “had the courage to put his head where his mouth was” (LHPP 140).

Philosophically, Locke’s main influence on Rawls concerns the issue of legitimacy. Rawls took Locke to have identified with remarkable clarity the source of this problem: the fact that people are morally symmetrically positioned. In his Two Treatises of Government (Locke 1960 [1689]), Locke argued that all individuals are naturally free and equal, and that this means that no one has natural authority over anyone else. This gives rise to the problem of legitimacy. How can government, claiming precisely such authority, be justified?

Rawls also agreed with Locke about the major outlines of how this problem is to be solved. Both adopted a social contract approach. If political society can be seen as the result of a contract between all its members, then the terms of interaction that it imposes on them can be seen as agreed upon. Such agreement would render the exercise of political power importantly self-imposed and thus compatible with the status of all as free and equal. Rawls and Locke thus shared a vision of a fully legitimate society as one in which citizens are facing laws that they can regard as self-imposed. One concrete implication of this is that, for both Rawls (most explicitly in Political Liberalism) and Locke (most explicitly in A Letter Concerning Toleration (Locke 2010 [1689])), political authority must remain confined to what is of genuinely public concern. Religious matters, and other views about the good life, as such are thus categorically ruled out of the court of politics.