Thomas Reid (1710-96), the Scottish natural and moral philosopher, was one of the founding members of the Aberdeen Philosophical Society and a significant figure in the Scottish Enlightenment. Reid believed that common sense should form the foundation of all philosophical inquiry. He criticised the sceptical philosophy propagated by his fellow Scot David Hume and the Anglo-Irish bishop George Berkeley, who asserted that the external world did not exist outside the human mind. Reid was also critical of the theory of ideas propagated by Locke and Descartes, arguing that it was incompatible with physical and experiential facts. For Reid, our senses demonstrate that the external world must exist, and this work is organised in chapters examining each of the senses in turn. The book, based on his lectures, was first published in 1764 when Reid was a regent professor at King's College, Aberdeen, and was reissued in 1818.

Thomas Reid (1710-1796) was a philosopher who founded the Scottish school of 'common sense'. Much of Reid's work is a critique of his contemporary, David Hume (1711-1776), whose empiricism he rejects. In this work, written after Reid's appointment to a professorship at the university of Glasgow, and published in 1785, he turns his attention to ideas about perception, memory, conception, abstraction, judgement, reasoning and taste. He examines the work of his predecessors and contemporaries, arguing that 'when we find philosophers maintaining that there is no heat in the fire, nor colour in the rainbow ... we may be apt to think the whole to be only a dream of fanciful men, who have entangled themselves in cobwebs spun out of their own brain'. Written by one of the Scottish Enlightenment's most important thinkers, this work brings to life the intellectual debates of the time.

Essays on the Active Powers of Man (1788) was Thomas Reid's last major work. It was conceived as part of one large work, intended as a final synoptic statement of his overall philosophy. The first and larger part was published three years earlier as Essays on the Intellectual Powers of Man (edited as volume 3 of the Edinburgh Edition of Thomas Reid). These two works are united by Reid's basic philosophy of Common Sense, which sets out native principles by which the mind operates in both its intellectual and active aspects. The Active Powers shows how these principles are involved in volition, action, and the ability to judge morally. Reid gives an original twist to a libertarian and realist tradition that was prominently represented in eighteenth-century British thought by such thinkers as Samuel Clarke and Reid's near contemporary and acquaintance, Richard Price.

Traditionally seen as an epistemologist, Reid has in much recent work emerged as a significant contributor to the philosophy of action and to ethics. This edition of the Active Powers will be of interest not only to historians of philosophy but also to philosophers working on the theory of action, on the problem of free will, and in moral psychology and meta-ethics.