Thomas Reid's Inquiry (1764) stems from the philosophical problem of the relationship between the real world and the mind. Dissatisfied with the empiricists, Ried attempted to answer the skepticism of Geroge Berkeley, John Locke, and David Hume. Ried felt that the Ideal System of modern philosophy up to that point led to skepticism about the material world, skepticism which is not a useful result to the common man, and instead proposed direct realism. On a humorous note, this book is split up into chapters named after and based upon each of the five senses ("Of Tasting", "Of Touch", etc.), but a couple of the chapters, Ried says, describe senses of such similarity ("Of Tasting" is to "Of Smelling") or are of lead to a different type of philosophy ("Of Hearing" leads to linguatics) that he does not feel the need to go into them, and are only 3-7 pages long, while "Of Seeing" is over 100 pages in most editions!

Reid wanted to answer David Hume's A Treatise of Human Nature. Reid read Humes argument as starting with Isaac Newton's second rule of philosophising, like causes may be infered from like effects (which is a lot like ancient philosophy's maxim "nothing comes from nothing"). Hume goes on to show that enumerative induction would always end up being circular. Rene Descartes appeal to a perfectly good creator still requires reasoning, and we have no reason to rely on that much reasoning, so Hume argues, and Reid agrees, that argument fails.

But Hume's argument (indeed John Locke's and Bishop George Berkeley's amoung others do as well) leads to skepticism about the real world, an unpaletable solution to Reid. Reid's responce in the inquiry follows the basic precepts of Providential Naturalism. Noting that there must be a direct realism by the mind of the material world, Reid argues that any natural connection must be accounted for by some law of nature. If there is no such law yet known, either there is such a law that explains the connection that will be found in the future, or the connection itself is such a natural law. Reid goes on to say thatall of the law of nature are consequences of the will of the Creator. Ried concludes that in determining the laws of the human mind, man can understand the purpose of the existence of the mind, and thus himself. Hence truth is within reach of the philosophers. Ried caveats that if we are wrong about this, it is by design of the Creator, and we are hopelessly lost.