Thomas Reid was the founder of the Scottish "Common Sense" school of philosophy. A contemporary and critic of David Hume, he is best known for his staunch defense of common sense and trenchant opposition to the "way of ideas," the theory that the immediate objects of perception and other cognitive acts are always internal images or ideas, not external physical objects. His views exerted a good deal of influence until the mid-nineteenth century or so, when they began to be eclipsed by absolute idealism, pragmatism, and other philosophical movements, but they have been the subject of renewed interest from the 1970s on.

After being educated at Marischal College in Aberdeen, Scotland, Reid served for fifteen years as a parish minister in nearby New Machar. In 1752 he was appointed professor at King's College in Aberdeen, where he taught mathematics, physics, and philosophy, among other subjects...