Dugald Stewart (1753-1828), Scottish philosopher, was born in Edinburgh on the 22nd of November 1753, the only surviving child of Matthew Stewart (1715-1785), who was Professor of Mathematics in the University of Edinburgh between 1747 and 1772, and Marjorie Stuart. Dugald Stewart was educated in Edinburgh at the high school and the university, where he read mathematics and moral philosophy under Adam Ferguson. In 1771, he went to Glasgow, where he attended the classes of Thomas Reid, and was particularly influenced by Reid's An Inquiry into the Human Mind on the Principles of Common Sense (1764). In Glasgow he boarded with Archibald Alison, author of the Essay on Taste, and a lasting friendship sprang up between them.
"What we commonly call sensibility, depends, in a great measure, on the power of imagination. Point out two men, any object of compassion; --a man, for example, reduced by misfortune from easy circumstances to indigence. The one feels merely in proportion to what he perceives by his senses. The other follows, in imagination, the unfortunate man to his dwelling, and partakes with him and his family in their domestic distresses.... As he proceeds in the painting, his sensibility increases, and he weeps, not for what he sees, but for what he imagines. It will be said, that it was his sensibility which originally aroused his imagination; and the observation is undoubtedly true; but it is equally evident, on the other hand, that the warmth of his imagination increases and prolongs his sensibility." (From Elements of the Philosophy of the Human Mind (1792).
After one session in Glasgow, the 19-year old Dugald was summoned by his father, whose health failing, to take over his mathematical classes in the University of Edinburgh. In 1775, he was elected Professor of Mathematics jointly with him. Three years later, Adam Ferguson was appointed secretary to the commissioners and was sent to the American colonies, and Stewart lectured as his substitute. Thus in 1778-1779 he also delivered lectures on morals.
In 1783, he married Helen Bannatyne, who died in 1787, leaving an only son, Matthew. In 1785 he succeeded Ferguson in the chair of moral philosophy, which he filled for a quarter of a century and made Edinburgh a centre of intellectual and moral influence. Students were attracted by his reputation from England, and even from the Continent and America. Among them were Sir Walter Scott, Sydney Smith, Lord Brougham, Dr Thomas Brown, James Mill, Sir James Mackintosh and Sir Archibald Alison, and two future Prime Ministers. The course on moral philosophy embraced lectures on political philosophy, and from 1800 onwards a separate course of lectures was delivered on political economy, then almost unknown as a science. In the aftermath of the French Revolution, Stewart's political teaching aroused suspicion of his disaffection from the constitution. The summers of 1788 and 1789 he spent in France, where he met Suard, Degerando, Raynal, and came to sympathize with the revolutionary movement.
In 1790 Stewart married again; Helen D'Arcy Cranstoun, who became his wife, was a lady of birth and accomplishments, and he was in the habit of submitting to her criticism whatever he wrote. They had a son and a daughter; the death of the former in 1809 was a severe blow to his father, and precipitated his retirement from active duties teaching. In 1809-1810, his place was taken by Thomas Brown, who in 1810 was appointed conjoint professor. When Brown died, in 1820, Stewart retired altogether from the professorship, which was conferred upon John Wilson, better known as "Christopher North." After 1809 Stewart lived mainly at Kinneil House, Linlithgowshire, which was placed at his disposal by the duke of Hamilton. In 1822 he was struck with paralysis, but recovered enough to enable him to resume his studies. He died in Edinburgh on 11th June 1828. A monument to his memory was erected on Calton Hill in 1831, designed by William Henry Playfair, modelled on the Choragic Monument of Lysicrates in Athens - fittingly, as it was Stewart who first compared Edinburgh to Athens, giving rise to its soubriquet "the Athens of the North".
The Dugald Stewart Building in Crichton Street, Edinburgh is named in his memory. Opened in 2008, it provides a forum for about 500 researchers in Informatics: Artificial Intelligence, Cognitive Science, Computer Science, and Systems Biology.
Stewart's publications include Outlines of Moral Philosophy (1793), Philosophical Essays (1810), and Philosophy of the Active and Moral Powers of Man (1828). His major publication, however, was Elements of the philosophy of the human mind which appeared in three parts; the first in 1792, the second in 1814 and the third in 1827.
Stewart's philosophical views were very similar to those of Reid. He upheld Reid's psychological method and expounded the "common-sense" doctrine. He was a thorough inductionist in philosophy and psychology but was sensitive to the realistic interpretations of Kepler and Galileo, for whom hypotheses were not simply instrumental devices. His work is thus a connecting link between naive inductivism and later technical views on scientific theory. His affinity for the mathematics led him often to analogies between the axioms of mathematics and the laws that govern human thinking.