The Online Library of Liberty

A project of Liberty Fund, Inc.

• Selections From the Scottish Philosophy of Common Sense
• Introduction
• Thomas Reid
• I.—: Introduction to the Philosophy of Common Sense
• § 1.: The Importance of the Subject, and the Means of Prosecuting It
• § 2.: The Impediments to Our Knowledge of the Mind
• II.—: Analysis of a Typical Sensation
• § 1.: The Sensation Considered Abstractly
• § 2.: Sensation and Remembrance, Natural Principles of Belief
• § 3.: Judgment and Belief In Some Cases Precede Simple Apprehension
• § 4.: Two Theories of the Nature of Belief Refuted—conclusions From What Hath Been Said
• § 5.: Apology For Metaphysical Absurdities—sensation Without a Sentient, a Consequence of the Theory of Ideas—consequences of This Strange Opinion
• § 6.: The Conception and Belief of a Sentient Being Or Mind Is Suggested By Our Constitution—the Notion of Relations Not Always Got By Comparing the Related Ideas
• § 7.: There Is a Quality Or Virtue In Bodies, Which We Call Their Smell—how This Is Connected In the Imagination With the Sensation
• § 8.: That There Is a Principle In Human Nature, From Which the Notion of This, As Well As All Other Natural Virtues Or Causes, Is Derived
• § 9.: Whether In Sensation the Mind Is Active Or Passive?
• III.—: Knowledge and Reality
• § 1.: Of Hardness
• § 2.: Of Natural Signs
• § 3.: Of Extension
• § 4.: Of the Visible Appearances of Objects
• § 5.: Of Perception In General
• § 6.: Of the Process of Nature In Perception
• Appendix: of Cause and Power
• IV.—: The Operations of the Mind
• § 1.: Principles Taken For Granted
• § 2.: Of Hypotheses and Analogy
• § 3.: Of Perception
• § 4.: Of Sensation
• § 5.: Of Primary and Secondary Qualities
• § 6.: Of Conception
• § 7.: Of Judgment
• § 8.: Of Common Sense
• § 9.: The First Principles of Contingent Truths
• § 10.: First Principles of Necessary Truths
• V.—: Of Morals
• § 1.: Of Benevolent Affection In General
• § 2.: There Are Rational Principles of Action In Man
• § 3.: Of Regard to Our Good On the Whole
• § 4.: Of the Notion of Duty, Rectitude, Moral Obligation
• § 5.: Observations Concerning Conscience
• § 6.: That Moral Approbation Implies a Real Judgment
• Adam Ferguson
• Of Man’s Progressive Nature
• James Beattie
• Of the Perception of Truth In General
• Dugald Stewart
• I.—: Of the Object of Philosophy, and the Method of Prosecuting Philosophical Inquiries
• II.—: Of the Association of Ideas
• III.—: Of the Power Which the Mind Has Over the Train of Its Thoughts
• IV.—: Of the Influence of Association On Our Active Principles, and On Our Moral Judgments
• V.—: Of Certain Laws of Belief, Inseparably Connected With the Exercise of Consciousness, Memory, Perception, and Reasoning

§ 8.

That there is a Principle in Human Nature, from which the Notion of this, as well as all other Natural Virtues or Causes, is derived

In order to illustrate further how we come to conceive a quality or virtue in the rose which we call smell, and what this smell is, it is proper to observe, that the mind begins very early to thirst after principles which may direct it in the exertion of its powers. The smell of a rose is a certain affection or feeling of the mind; and, as it is not constant, but comes and goes, we want to know when and where we may expect it; and are uneasy till we find something which, being present, brings this feeling along with it, and, being removed, removes it. This, when found, we call the cause of it; not in a strict and philosophical sense, as if the feeling were really effected or produced by that cause, but in a popular sense; for the mind is satisfied if there is a constant conjunction between them; and such causes are in reality nothing else but laws of nature. Having found the smell thus constantly conjoined with the rose, the mind is at rest, without inquiring whether this conjunction is owing to a real efficiency or not; that being a philosophical inquiry, which does not concern human life. But every discovery of such a constant conjunction is of real importance in life, and makes a strong impression upon the mind.

So ardently do we desire to find everything that happens within our observation thus connected with something else as its cause or occasion, that we are apt to fancy connections upon the slightest grounds; and this weakness is most remarkable in the ignorant, who know least of the real connections established in nature. A man meets with an unlucky accident on a certain day of the year, and, knowing no other cause of his misfortune, he is apt to conceive something unlucky in that day of the calendar; and, if he finds the same connection hold a second time, is strongly confirmed in his superstition. I remember, many years ago, a white ox was brought into this country, of so enormous a size that people came many miles to see him. There happened, some months after, an uncommon fatality among women in child-bearing. Two such uncommon events, following one another, gave a suspicion of their connection, and occasioned a common opinion among the country-people that the white ox was the cause of this fatality.

However silly and ridiculous this opinion was, it sprung from the same root in human nature on which all natural philosophy grows—namely, an eager desire to find out connections in things, and a natural, original, and unaccountable propensity to believe that the connections which we have observed in time past will continue in time to come. Omens, portents, good and bad luck, palmistry, astrology, all the numerous arts of divination and of interpreting dreams, false hypotheses and systems, and true principles in the philosophy of nature, are all built upon the same foundation in the human constitution, and are distinguished only according as we conclude rashly from too few instances, or cautiously from a sufficient induction.

As it is experience only that discovers these connections between natural causes and their effects; without inquiring further, we attribute to the cause some vague and indistinct notion of power or virtue to produce the effect. And, in many cases, the purposes of life do not make it necessary to give distinct names to the cause and the effect. Whence it happens, that, being closely connected in the imagination, although very unlike to each other, one name serves for both; and, in common discourse, is most frequently applied to that which, of the two, is most the object of our attention. This occasions an ambiguity in many words, which, having the same causes in all languages, is common to all, and is apt to be overlooked even by philosophers. Some instances will serve both to illustrate and confirm what we have said.

Magnetism signifies both the tendency of the iron towards the magnet, and the power of the magnet to produce that tendency; and, if it was asked, whether it is a quality of the iron or of the magnet, one would perhaps be puzzled at first; but a little attention would discover, that we conceive a power or virtue in the magnet as the cause, and a motion in the iron as the effect; and, although these are things quite unlike, they are so united in the imagination, that we give the common name of magnetism to both. The same thing may be said of gravitation, which sometimes signifies the tendency of bodies towards the earth, sometimes the attractive power of the earth, which we conceive as the cause of that tendency. We may observe the same ambiguity in some of Sir Isaac Newton’s definitions; and that even in words of his own making. In three of his definitions, he explains very distinctly what he understands by the absolute quantity, what by the accelerative quantity, and what by the motive quantity, of a centripetal force. In the first of these three definitions, centripetal force is put for the cause, which we conceive to be some power or virtue in the centre or central body; in the last two, the same word is put for the effect of this cause, in producing velocity, or in producing motion towards that centre.

Heat signifies a sensation, and cold a contrary one; but heat likewise signifies a quality or state of bodies, which hath no contrary, but different degrees. When a man feels the same water hot to one hand and cold to the other, this gives him occasion to distinguish between the feeling and the heat of the body; and, although he knows that the sensations are contrary, he does not imagine that the body can have contrary qualities at the same time. And when he finds a different taste in the same body in sickness and in health, he is easily convinced that the quality in the body called taste is the same as before, although the sensations he has from it are perhaps opposite.

The vulgar are commonly charged by philosophers, with the absurdity of imagining the smell in the rose to be something like to the sensation of smelling; but I think unjustly; for they neither give the same epithets to both, nor do they reason in the same manner from them. What is smell in the rose? It is a quality or virtue of the rose, or of something proceeding from it, which we perceive by the sense of smelling; and this is all we know of the matter. But what is smelling? It is an act of the mind, but is never imagined to be a quality of the mind. Again, the sensation of smelling is conceived to infer necessarily a mind or sentient being; but smell in the rose infers no such thing. We say, this body smells sweet, that stinks; but we do not say, this mind smells sweet and that stinks. Therefore, smell in the rose, and the sensation which it causes, are not conceived, even by the vulgar, to be things of the same kind, although they have the same name.

From what hath been said, we may learn that the smell of a rose signifies two things: First, a sensation, which can have no existence but when it is perceived, and can only be in a sentient being or mind; Secondly, it signifies some power, quality, or virtue, in the rose, or in effluvia proceeding from it, which hath a permanent existence, independent of the mind, and which, by the constitution of nature, produces the sensation in us. By the original constitution of our nature, we are both led to believe that there is a permanent cause of the sensation, and prompted to seek after it; and experience determines us to place it in the rose. The names of all smells, tastes, sounds, as well as heat and cold, have a like ambiguity in all languages; but it deserves our attention, that these names are but rarely, in common language, used to signify the sensations; for the most part, they signify the external qualities which are indicated by the sensations—the cause of which phænomenon I take to be this. Our sensations have very different degrees of strength. Some of them are so quick and lively as to give us a great deal either of pleasure or of uneasiness. When this is the case, we are compelled to attend to the sensation itself, and to make it an object of thought and discourse; we give it a name, which signifies nothing but the sensation; and in this case we readily acknowledge that the thing meant by that name is in the mind only, and not in anything external. Such are the various kinds of pain, sickness, and the sensations of hunger and other appetites. But, where the sensation is not so interesting as to require to be made an object of thought, our constitution leads us to consider it as a sign of something external, which hath a constant conjunction with it; and, having found what it indicates, we give a name to that: the sensation, having no proper name, falls in as an accessory to the thing signified by it, and is confounded under the same name. So that the name may, indeed, be applied to the sensation, but most properly and commonly is applied to the thing indicated by that sensation. The sensations of smell, taste, sound, and colour, are of infinitely more importance as signs or indications, than they are upon their own account; like the words of a language, wherein we do not attend to the sound but to the sense.