Discoveries
OF THE
ANCIENTS AND MODERNS.
No. II.
The Method and Logic of Descartes and Locke derived from the Ancients.
Within the last two centuries some notions were advanced in logic and metaphysics, which were taken to be new; and Descartes, Leibnitz, Mallebranche, and Locke, were regarded as innovators, although nothing be put forth in their works, but what is clearly laid down in those of the ancients.
Descartes sets forth, as a first principle, that whoever searches for truth, ought once in his lifetime at least to doubt of every thing. He then lays down the four following rules, wherein consists the whole of his logic.—1. Never to admit any thing as true, but what we evidently discern to be so; that is, we should carefully avoid rashness and prejudice, and assent to nothing, till it present itself so clearly to the mind, that there be no occasion to hesitate about it.—2. To reduce every difficulty into as many separate parts, as may be necessary to come at its solution.—3. So to arrange our thoughts, that we may gradually arise from the more simple and obvious, to the more complex and remote, adhering to the order wherein they naturally precede one another.—4. To take so extensive a view of our subject, and be so exact in the enumeration of its parts, that nothing may escape our observation.
The first of these principles of doubt and circumspection, so boasted of in Descartes, is clearly laid down by Aristotle, and forcibly recommended by the very arguments that Descartes assumes. “Whoever seeks after instruction,” says Aristotle, “ought first of all to learn to doubt; for that simplicity of mind, which accompanies hesitation, contributes to the discovery of truth:” and, “whoever searches for truth, without beginning his investigation by doubting of every thing, is like one who wanders he knows not whither, and having no fixed scope, cannot determine where he is; whilst, on the contrary, he who hath learned to doubt, so as to inquire, will find, in the end, the place where he ought to rest.” So, also, speaking of the method to be observed in our investigations, Aristotle bids us begin always with what is most evident and best known; and carefully trace to its first elements and principles whatever is obscure, by properly severing and defining them.
Descartes imagined he had been the first discoverer of one of the most proper engines for sapping and demolishing the great bulwark of scepticism, when he reared even upon doubt itself a basis for truth; for he looked upon himself as the original advancer of the Enthymem,[275] “I doubt (or think) therefore I am.” To Descartes has been assigned the whole honour of this argument, though in reality it is to be found in St. Augustine. “I do not see,” says that great man, “what mighty force there is in the scepticism of the academics. For my part, I look upon it as a very just observation of theirs, that we may deceive ourselves. But if I deceive myself, may I not thence conclude that I am? For he who has no existence, cannot deceive himself; wherefore, by that very circumstance, that I deceive myself, I find that I am.”
Locke, in his “Essay on the Human Understanding,” merely advances the fruits of an exact attention to the principles of Aristotle, who taught that all our ideas originally spring from the senses, insomuch that a blind man can never conceive the idea of colours, nor a deaf man of sounds; and who makes the senses to convey truth, so far as the imagination can discern it; and the understanding, so far as truth regards the conduct of life and morals. It was Aristotle who laid the foundation of that principle, so celebrated among the Peripatetics, that “there is nothing in the understanding but what came into it by the senses.” This principle diffuses itself through his works in a thousand places, and Locke was singularly indebted for the very foundation of his system to the Stoics. The basis of his work is, that our sensations are the materials which reflection makes use of to come at mental notions; and that our sensations are simple ideas. It is true, that he has thrown great light upon our manner of acquiring and associating ideas; but the Stoics reasoned in the very same manner; and if all that they advanced on this subject, in those works of which we have nothing now remaining but the titles, had reached our times, we had not needed the labours of a Locke. There is a most remarkable passage to this point in Plutarch. He says, “The foundation of the doctrine of Zeno and his school, as to logic, was, that all our ideas come from sensation. The mind of man at his birth, say they, is like white paper, adapted to receive whatever may be written on it. The first impressions that it receives come to it from the senses: if the objects are at a distance, memory retains those types of them; and the repetition of these impressions constitutes experience. Ideas or notions are of two kinds, natural and artificial. The natural have their source in sensation, or are derived from the senses; whence they also gave them the name of anticipations: the artificial are produced by reflection, in beings endowed with reason.” This passage, and others in Origen, Sextus Empiricus, Diogenes Laertius, and St. Augustine, may serve to trace the true origin of the principle, “That there is nothing in the understanding, but what entered into it by the senses.” It may be observed, that this axiom, so clearly expressed by the ancient Stoics and Epicureans, and by Locke among the moderns, has been erroneously attributed by several learned men, especially Gassendi and Harvey, to Aristotle.
[275] Enthymem: an argument consisting only of an antecedent and consequential proposition; a syllogism, where the major proposition is suppressed, and only the minor and consequence produced in words. Johnson.