Thomas Reid
Scottish philosopher (1710–1796), born in Strachan, Aberdeenshire, into a family of Presbyterian clergymen, educated at the University of Aberdeen, where he later taught for years before succeeding Adam Smith in 1764 to the chair of moral philosophy at the University of Glasgow, and generally regarded as the founder of the so-called 'Scottish common sense school', a philosophical current that exerted decisive influence on both British and American academic philosophy for over a century. His fundamental work, An Inquiry into the Human Mind on the Principles of Common Sense (1764), undertook a systematic, rigorous critique of what Reid called the 'theory of ideas', the epistemological framework shared by Descartes, Locke, Berkeley and, above all, Hume, according to which the human mind has direct access only to its own ideas or internal representations, never to external objects themselves — a framework which, Reid argued, inevitably led, through an unrelenting logical process, to Hume's radical scepticism regarding the existence of the external world, personal identity and causation. Confronting this sceptical drift, which he considered philosophically coherent but existentially untenable and contrary to the common sense of any reasonable person, Reid defended direct realism: perception gives us immediate, non-inferential access to external objects themselves, not to mere mental representations of them, and this basic trust in the reliability of our natural cognitive faculties — perception, memory, testimony, reasoning — constitutes a set of rationally unavoidable 'first principles' that neither require nor admit further demonstration, being the foundation on which all subsequent philosophical inquiry must be built rather than something to be called into question by it. Reid also developed an influential theory of free moral agency grounded in this same common-sense realism, arguing against the determinism of Hobbes and others that our immediate experience of freedom of the will is likewise an undeniable basic principle of practical reason. His philosophy, although eclipsed during the nineteenth century by Kantian and Hegelian idealism, has undergone a notable contemporary philosophical rehabilitation as a direct precursor of the epistemology of direct realism and of the 'epistemological reformism' of twentieth-century analytic philosophy.