Plato's Allegory of the Cave and Reid's

Thomas Reid: The Scottish School of Common Sense Realism

Reid recognizes to some extent that Hume was not a total skeptic.

Indeed, he ingenuously acknowledges, that it was only in solitude and retirement that he could yield any assent to his own philosophy; society, like day-light, dispelled the darkness and fog of scepticism, and made him yield to the dominion of common sense. (Inquiry, Chapter I, Introduction, Section V; see Hume's Treatise, Book I, Part IV, Section 7)

Hume's inability to remain skeptical was taken by Reid to be an inconsistency on his part and a demonstration of the weakness of philosophical reasoning in the face of common sense.

Reid held that common sense will always win the contest with philosophy, "for, in reality, Common Sense holds nothing of Philosophy, nor needs her aid" (Inquiry, Chapter I, Introduction, Section IV). Indeed, it is philosophy that stands in need of the aid of common sense to keep it from falling into skepticism.

Philosophy . . . has no other root but the principles of Common Sense; it grows out of them, and draws its nourishment from them. Severed from this root, its honours wither, its sap is dried up, it dies and rots. (Inquiry, Chapter I, Introduction, Section VII)

On the other hand, it is easy to see why philosophers would be inclined to criticize a system that takes common sense as its starting point. The views of ordinary, non-philosophical people seem to be quite unreflective and indeed riddled with error. Philosophers have tended to view their task as being to rise above the common view of things and present a more lofty picture of the universe. Reid does not fall victim to this kind of criticism, however. His account of "common sense," as outlined in the Essays on the Intellectual Powers of Man, Essay VI, Chapter 2, was itself a philosophical one.

Reid begins by explaining what is "common" about "common sense." He thought that common sense is something which nearly all human beings have. The only ones who lack it are defective in some way, victims of "lunacy." A person who, through some natural mental defect, believes he is made of glass has departed from common sense. And a skeptical philosopher who does not believe that mind-independent bodies exist has similarly taken leave of common sense. The difference is that the philosopher abandons common sense not due to a mental defect, but rather due to the influence of metaphysical arguments. So Reid describes a skeptic as a victim of "metaphysical lunacy."

Self-evident beliefs can be divided according to whether they are about what is necessary (what is immutable, and whose contrary is impossible) or about what is contingent (what is mutable, and whose contrary is possible). Beliefs that are self-evident and necessary are called "axioms," and they include basic beliefs about mathematics. Such beliefs are infallible. "The light of truth so fills my mind in these cases, that I can neither conceive nor desire anything more satisfactory" (Essays on the Intellectual Powers of Man, Essay II, Chapter XX). Among the self-evident beliefs about necessary truths are the following:

· Of grammar: every complete sentence must have a verb.

· Of logic: no proposition can be both true and false.

· Of morals: no one ought to be blamed for an action he could not prevent.

· Of metaphysics:

· Sensible qualities and thoughts must have a subject.

· Whatever begins to exist must have a cause which produced it.

· We can infer with certainty from marks or signs of intelligent design in the effect that its cause designed it intelligently.

A further distinction can be drawn in the domain of contingent self-evident beliefs. Some are quite general while others are particular. Reid called the former "first principles," including the following (Essays on the Intellectual Powers of Man, Essay VI, Chapter V):

· The existence of everything of which I am conscious.

· The thoughts of which I am conscious, are the thoughts of a being which I call myself, my mind, my person.

· Those things do really exist which we distinctly perceive by our senses, and are what we perceive them to be.

· The natural faculties, by which we distinguish truth from error, are not fallacious.

· We have some degree of power over our own actions and what we will.

· We continue to exist as identical beings, as far back as we can distinctly remember.

· What is to be in the phenomena of nature will probably be like what has been.

Reid and Hume

A final point concerns Reid's portrayal of Hume as an extreme skeptic. Hume acknowledged that his philosophy is very skeptical, but does it really depart from common sense? Hume explicity recognized that nature prevents us from being skeptics with respect to the independent existence of bodies for more than short periods of time. He conceded that the same kind of judgments Reid called "common sense" come naturally to the ordinary person.

Hume described our "natural" beliefs as being the fictitious products of the imagination, rather than as "a gift from Heaven" or a product of "the will of Him who made us." Hume was skeptical about any explanation of the human condition which appeals to the supernatural, especially when a wholly natural explanation can be given in its stead. It is better to recognize the extreme limitations of our power of judgment than to invent a divine basis for judgment which can never be proved to exist or even to be very probable. (See especially his Dialogues Concerning Natural Religion and  Section XI  of An Enquiry Concerning Human Understanding.)

Reid, on the other hand, held that a belief in intelligent design is self-evident. Moreover, he thought that Hume's attempt to explain all the workings of the human mind by his meager three principles of association produces only a caricature of the human being (Inquiry, Chapter I, Introduction, Section VI).