PHILOSOPHICAL INQUIRY.

IN the Introductory Dissertation I have ventured to offer some speculations upon the Trinity and Theology of the Gentiles, which differ widely from the opinions of almost all who have written upon the subject; I would therefore lay before the reader such grounds for the opinion as have induced me to adopt it. But I find it impossible to do so without instituting a short comparative inquiry into the method, objects and result of the ancient and modern systems of Philosophy; and I trust it will not be deemed misplaced, for I conceive that in the neglected writings of the ancients there lies concealed a mine of metaphysical knowledge of such practical utility as would amply repay the trouble of opening it again.

If we were to ask, what was conceived to be the great engine of invention and discovery among the ancients, it is highly probable we should be answered that it was Syllogism; and if we were to ask the same question relative to modern science, we should be unhesitatingly assured that it was Induction; and possibly at the same time we might be told, that the method of the ancients was something worse than useless. Yet, when we come to consider, that in all ages human nature has been the same, and that such admirable productions have been the result of human effort both in ancient and modern times, we shall find reason to suspect that the methods of discovery, or the tools really used in all ages, have been much alike, though their names may have been

misapplied, or they may have been used without having had any distinct appellations assigned them.

By the Inductive method we are supposed to go about to collect, by experience and observation, all the facts and circumstances within our reach, relative to the subject in hand. We must examine them in every light, compare their similarities, and mark their differences; we must reject whatever does not properly relate to the subject, and conclude upon the affirmatives that are left. By these means, from the individuals we rise to some general proposition, and we rest assured in its truth as proved experimentally.

To take a common instance: A child that has been burnt by a flame naturally expects the same result from the same cause; indeed he is said to feel sure of it from experience: and in the expectation of the same result from similar causes, he is said to reason by a species of Induction, though not founded on an enlarged experience. But by trying experiments upon all objects which have the appearance of flame, he would learn to distinguish such as are hurtful from such as are otherwise, and excluding those that are harmless, he arrives at the conclusion, that all such objects of a particular kind are hurtful.

Now, in this statement of the process, it appears to me that two very different instruments are used; the first of which seems to be Analogy, avaλoyía, a reasoning upwards from the known to the unknown, the great instrument of Invention and Generalization, which provides, as it were, subjects for the exercise of Induction; which Induction, èzaywyn, seems to be rather the collection and examination of experiments, and the drawing a conclusion therefrom; and as this conclusion cannot be extended beyond what is warranted by the experiments, the Induction is an Instrument of Proof and Limitation. A person that has been burnt by a flame is positively certain that he will be burnt again if he try it; he argues only from same to same, and is sure of it by experience; and it is upon this innate natural expectation that all physical science is founded. By analogy he argues that all flames will burn him, he argues from like to like, he generalizes

and draws an inference; and I conceive it is by this analogical reasoning that all science is advanced. The inference which he thus draws a priori, is merely an hypothesis, imóveis, a supposition, probable indeed, but far from satisfactory. But when he brings it to the proof by induction, and collects experiments, he either confutes, proves, or limits this hypothesis to something not quite so general.

This analogical reasoning, when it is extended only from individual to individual of the same species, is commonly called experience, and not analogy; and from the perfect uniformity of nature, perhaps not improperly: thus, we say, we know by experience that all stones gravitate to the earth. But when we extend it from species to species of the same genus, it is analogy properly so called. If from the gravitation all stones we reason to that of apples, we reason by analogy, from like to like; we obtain a probable conclusion, not satisfactory till experiment be directed to the point, and it be proved. Having thus included apples as well as stones, we may proceed from one species to another by the same process of analogy and proof, till all bodies upon the surface of the earth be included under the general law of gravitation, whence we may rise to more general propositions. And I am inclined to think that such has been the common process of discovery in all ages of the world.

When Sir I. Newton, from the fall of an apple, was led to the consideration of the moon's gravity, he is said to have made the discovery by Induction; which is true as far as the proof of it went. But it is manifest, that at first he merely formed a probable hypothesis by Analogy, and then laboriously brought it to the test of observation; and it is highly probable that the hypothesis he formed was, that the moon gravitated to the earth with a constant force, instead of a force varying inversely as the square of the distance; which most likely was the result of another hypothesis, after he had proceeded so far as to ascertain that she did really gravitate, but not according to the law presumed.

When Harvey observed the valves in the veins he is com

monly said to have made the discovery of the circulation of the blood, by reasoning from Final causes, or by asking of nature for what purpose such valves could be intended: but perhaps he might have asked the question for ever, unless the analogy between the valve and that of a pump had suggested a plausible hypothesis, which he proved by repeated experiments directed to the point.

Analogy, so much slighted and overlooked, and to which such an inferior part in the advancement of science has been assigned, and that too with so much suspicious caution, appears to be the great instrument of generalization and invention by which hypotheses are supplied, which are most commonly the subjects for the exercise of Induction. By Induction, as usually understood, we make it a rule to exclude all hypotheses: first of all, we collect the experiments, and having obtained these, we are next to examine them and compare them; we reject the irrelative and negative, and conclude upon the affirmatives that are left. By this means, says Lord Bacon, we question nature, and conclude upon her answers yet I would venture to suggest, that, ninety-nine times out of a hundred, the Analogy or comparison precedes the collection of the experiments; some resemblance is observed, some hypothesis is started, which is the subject that is brought to the test of Induction. By this the hypothesis is either proved, or confuted, or more commonly limited to something less general. I would not be understood to assert that the common inductive method is barren, for, no doubt, discoveries are sometimes so made; but thousands and thousands of inventions are brought into play, the result merely of analogy and a few experiments, or a single experimentum crucis. By the common method proposed we take too wide a range, we embrace the whole subject at once, and require the completion of its natural history, but by the proper use of Analogy as a guide, we step cautiously but from one species to the next.

Induction has two instruments of operation; Experiment for all things within our reach, and Observation for those beyond us. And of these Observation is less efficient than Experiment, for it