The trajectory of John Locke's impact in the eighteenth century has been traced in numerous ways by historians of philosophy. The most familiar approach has been to link him with Berkeley and Hume as part of a group which developed (and complicated) an empirical account of knowledge acquisition. This book describes an alternative triptych, connecting Locke with the third Earl of Shaftesbury and Francis Hutcheson. The argument between them focused on the problem of diversity and the question of whether any moral consistency could be located in mankind. Such a perspective explicitly joins their work with a number of current concerns in philosophy and politics, giving this study a dual purpose: to recover a neglected theme in intellectual history, in which a debate over the content of human nature and issues of cultural difference emerged during the English, Irish, and Scottish Enlightenments; and in conclusion, to explore the relationship between these arguments and some major dilemmas in contemporary thought.

Locke's decisive role was ensured by the publication of the Essay concerning Human Understanding (1690) and above all the opening book in which he supplied a critique of innate ideas and principles. In order to unseat the mistaken notion that human beings inherently recognise certain moral truths as well as the idea of the divine, Locke pointed out evidence of widespread cultural diversity: what one country embraced, another one abhorred. Some groups believed in God and others remained entirely atheist.