Thomas Brown (1778-1820), Scottish philosopher, was born at Kirkmabreck, Kirkcudbright, where his father was parish clergyman. He was a boy of a refined nature, a wide reader and an eager student. Educated at several schools in London, he went to Edinburgh University in 1792, where he attended Dugald Stewart's moral philosophy class. His attendance was desultory, and he does not appear to have completed his arts course. After studying law for a time he took up medicine; his graduation thesis De Somno was well received. But his great strength lay in metaphysical analysis, as was shown in his answer to the objections raised against the appointment of Sir John Leslie to the mathematical professorship (1805). Leslie, a follower of Hume, was attacked by the clerical party as a sceptic and an infidel, and Brown took the opportunity to defend Hume's doctrine of causality as in no way inimical to religion. His defence, at first only a pamphlet, became in its third edition a lengthy treatise entitled Inquiry into the Relation of Cause and Effect, and is a fine specimen of Brown's analytical faculty. In 1806 he became a medical practitioner in partnership with James Gregory, but, though successful in his profession, preferred literature and philosophy.

After twice failing in the attempt to gain a professorship in the university, he was invited, during an illness of Dugald Stewart in the session of 1808-1809, to act as his substitute, and during the following session he undertook a great part of Stewart's work. The students received him with enthusiasm, due partly to his splendid rhetoric and partly to the novelty and ingenuity of his views. In 1810 he was appointed as colleague to Stewart, a position which he held for the rest of his life. He wrote his lectures at high pressure, and devoted much time to the editing and publication of the numerous poems which he had written at various times during his life. He was also engaged in preparing an abstract of his lectures as a handbook for his class. His health, never strong, gave way under the strain of his work. He was advised to take a voyage to London, where he died on the 2nd of April 1820.

His friend and biographer, David Welsh (1793-1845), superintended the publication of his text-book, the Physiology of the Human Mind, and his Lectures on the Philosophy of the Human Mind was published by his successors, John Stewart and the Rev. E. Milroy. The latter was received with great enthusiasm both in England (where it reached its 19th edition) and in America; but recent criticism has lessened its popularity and it is now almost forgotten.

Brown's philosophy occupies an intermediate place between the earlier Scottish school and the later analytical or associational psychology. To the latter Brown really belonged, but he had preserved certain doctrines of the older school which were out of harmony with his fundamental view. He still retained a small quantum of intuitive beliefs, and did not appear to see that the very existence of these could not be explained by his theory of mental action. This intermediate or wavering position accounts for the comparative neglect into which his works have now fallen. They did much to excite thinking, and advanced many problems by more than one step, but they did not furnish a coherent system, and the doctrines which were then new have since been worked out with greater consistency and clearness.

Brown wrote a criticism of Darwin's Zoonomia (1798), and was one of the first contributors to the Edinburgh Review, in the second number of which he published a criticism of the Kantian philosophy, based entirely on Villers's French account of it. Among his poems, which are modelled on Pope and Akenside and rather commonplace, may be mentioned: Paradise of Coquettes (1814); Wanderer in Norway (1815); Warfiend (1816); Bower of Spring (1817); Agnes (1818); Emily (1819); a collected edition in 4 vols. appeared in 1820.

For a severe criticism of Brown's philosophy, see Sir W. Hamilton's Discussions and Lectures on Metaphysics; and for a high estimate of his merits, see J. S. Mill's Examination of Hamilton. See also D. Welsh's Account of the Life and Writings, etc. (1825); McCosh's Scottish Philosophy, pp. 317-337. The only German writer who seems to have known anything of Brown is Beneke, who found in him anticipations of some of his own doctrines. See Die neue Psychologie, pp. 320-330.