Thomas Reid (1710-1796) was a central figure in the Scottish Enlightenment, and founded the Scottish School of Common Sense. He believed that common sense should lead philosophy, or it would be useless to the common man. He critisized the so-called ideal theory of other modern philosophy, such as John Locke, Nicolas Malebranche, René Descartes, Bishop George Berkeley, and especially David Hume, claiming that all of their theories are basically the same and that they are all wrong. He claimed that their theories led to the same conclusion, skepticism! This is alarming considering Descartes' obvious goal of debunking the skeptics. Reid proposed a system where the mind could be directly aware of the material world (direct realism). In this, Reid was highly influenced by the ideas of "Providential Naturalism."

Critisizing other philosopher is a common and humorous practice stretching from Aristophanes' The Clouds. Reid's most famous works inclode An Inquiry into the Human Mind on the Principles of Common Sense (1764), the Essays on the Intellectual Powers of Man (1785) and the Essays on the Active Powers of Man (1788).

Reid was born in Strachan, Kincardineshire and educated at Aberdeen's Marischal College (1723-1731), worked as a minister in the Church of Scotland (1731-1751), and was a professor (regent) at Kings College, Aberdeen (1751-1764). In 1740 Reid married his cousin, Elizabeth Reid, and they had nine children, only one of whom survived them.