Hume's fiercest early critic argued doubting the outside world is unreasonable
Thomas Reid, a Scottish minister turned professor, answered David Hume's scepticism by insisting that some beliefs, such as the existence of an external world, come before reasoning rather than out of it. For decades he was ranked above Hume himself, and he replaced Adam Smith in a Glasgow chair.
Reid was born in the manse at Strachan in Aberdeenshire in 1710; his mother, Margaret Gregory, was a first cousin of the mathematician James Gregory. He entered Marischal College in Aberdeen in 1723 and graduated three years later, was licensed to preach in 1731, and served as a Church of Scotland minister until King's College, Aberdeen, made him a professor in 1752. In 1758 he helped found the Aberdeen Philosophical Society, nicknamed the Wise Club.
His first book, the Inquiry, which grounded knowledge of the mind in common sense, appeared in 1764, and soon afterwards Glasgow appointed him professor of moral philosophy in succession to Adam Smith. He stepped down in 1781 to turn his lectures into two books, on the intellectual powers of man in 1785 and on the active powers of the mind in 1788, and he co-founded the Royal Society of Edinburgh in 1783. He married his cousin Elizabeth in 1740 and outlived all but one of their many children. He died in Glasgow in 1796.
The target of his philosophy was the theory of ideas shared by Locke, Descartes and their successors, the view that the mind perceives only its own ideas. Hume concluded we could never know what the external world contains; Berkeley held that it simply consisted of ideas. Reid countered with direct realism. Anyone who argues at all already presupposes principles such as that the other person is real and that nature's laws hold steady, and reason requires these rather than proving them. Refusing them, he suggested, was closer to madness than to rigour. His favourite illustration: when he imagines a centaur, what he imagines is an animal, and no idea is an animal, so the object of thought is the centaur, not an idea. He sent Hume an early draft of the Inquiry; Hume found it lively but faulted its method.
Reid also separated sensation from perception, arguing that we attend to the object perceived and overlook the process by which sensations yield knowledge of real things. He held that language grew from natural signs such as gesture and tone, which is why a child can learn to speak before it grasps meanings, and he saw the arts as a recovery of that natural language.
Source: Thomas Reid
