Thomas Reid's Inquiry has long been recognized as a classic philosophical text. Since its first publication in 1764, there have followed no less than forty editions. The proliferation of secondary literature further indicates that Reid's work is flourishing as never before. Yet Reid scholars have been acutely aware of proceeding without the full textual evidence. There exist thousands of unpublished manuscript pages in Reid's hand, many of which relate directly to the composition of Inquiry. Furthermore, no account has been taken of the successive alterations made to the four editions published in Reid's lifetime. The present edition, therefore, aims to present a complete, critically edited text of the Inquiry, accompanied by a judicious selection of manuscript evidence relating to its composition. The volume contains an editor preface presenting the raison d'être for the edition followed by an introduction giving the central argument of the Inquiry by means of an historical and philosophical account of its formation; an account which also indicates the significance of the MSS contained in the section containing related documents. The critical text is based on the fourth life-time edition (1785), while the textual notes include bibliographical details and allusions, translations, references to secondary literature, and selected passages from Reid's MSS.