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• 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

§ 6.

Of the Process of Nature in Perception

Although there is no reasoning in perception, yet there are certain means and instruments, which, by the appointment of nature, must intervene between the object and our perception of it; and, by these, our perceptions are limited and regulated. First, If the object is not in contact with the organ of sense, there must be some medium which passes between them. Thus, in vision, the rays of light; in hearing, the vibrations of elastic air; in smelling, the effluvia of the body smelled—must pass from the object to the organ; otherwise we have no perception. Secondly, There must be some action or impression upon the organ of sense, either by the immediate application of the object, or by the medium that goes between them. Thirdly, The nerves which go from the brain to the organ must receive some impression by means of that which was made upon the organ; and, probably, by means of the nerves, some impression must be made upon the brain. Fourthly, The impression made upon the organ, nerves, and brain, is followed by a sensation. And, last of all, This sensation is followed by the perception of the object.

Thus, our perception of objects is the result of a train of operations; some of which affect the body only, others affect the mind. We know very little of the nature of some of these operations; we know not at all how they are connected together, or in what way they contribute to that perception which is the result of the whole; but, by the laws of our constitution, we perceive objects in this, and in no other way.1

Experience teaches us, that certain impressions upon the body are constantly followed by certain sensations of the mind; and that, on the other hand, certain determinations of the mind are constantly followed by certain motions of the body; but we see not the chain that ties these things together. Who knows but their connection may be arbitrary, and owing to the will of our Maker? Perhaps the same sensations might have been connected with other impressions, or other bodily organs. Perhaps we might have been so made as to taste with our fingers, to smell with our ears, and to hear by the nose. Perhaps we might have been so made as to have all the sensations and perceptions which we have, without any impression made upon our bodily organs at all.

However these things may be, if Nature had given us nothing more than impressions made upon the body, and sensations in our minds corresponding to them, we should, in that case, have been merely sentient, but not percipient beings. We should never have been able to form a conception of any external object, far less a belief of its existence. Our sensations have no resemblance to external objects; nor can we discover, by our reason, any necessary connection between the existence of the former, and that of the latter.1

[1 ]Ibid., pp. 184-186.

[1 ]Ibid., p. 187.