Aiming to construct a comprehensive analysis of Hume’s scattered linguistic references, it will be argued that the relevance of examining Hume’s characterisation of language relates directly to his claim that it is custom and convention, rather than autonomous reason or innate sentiment, which are principle means of shaping man’s social and moral character. As a result, references to language and language use by Hume served as a significant tool in illustrating and substantiating his more general theoretical claims regarding man’s social and moral character. Building upon the analysis of Hume, the thesis next turns its attention to an exploration of the influence of such linguistic assumptions on the moral theory of Adam Smith. While agreeing with many of Hume’s interpretations as to the character of language, it is clear that Smith did not share Hume’s faith in the ability of linguistic convention to serve as a reliable medium of moral guidance. Maintaining that Smith’s The Theory of Moral Sentiments and writings on rhetoric are at the centre of his thinking on language and language use, we will investigate how his characterisation of language is reflected in, and exercised influence upon, his conception of man’s morality and sociability. Perhaps the best example of the multifarious implications of language and language use in the presentation of man’s sociable and moral character amongst the theorists being discussed, Smith’s references to languages and language play a significant supportive role in the substantiation and dissemination of his theory. To highlight the influence of linguistic analysis on the period’s characterisation of morals, the final sage of the thesis explores the efforts of Thomas Reid to present a countervailing theory of morals from that of both Hume and Smith. Drawing upon Reid’s published works, private notes, and student lecture notes; the closing section examines Reid’s utilisation of a very different interpretation of the nature and role of language in his effort to challenge the forces of scepticism and moral relativism.