II.

Use and Abuse of Hypotheses in Philosophical Inquiries.-Diffe rence between Gratuitous Hypotheses, and those which are supported by presumptions suggested by Analogy.-Indirect Evidence which a Hypothesis may derive from its agreement with the Phenomena.-Cautions against extending some of these conclusions to the Philosophy of the Human Mind.

As some of the reasonings in the former part of this Section may, at first sight, appear more favourable to the use of Hypotheses than is consistent with the severe rules of the Inductive Logic, it may not be superfluous to guard against any such misapprehensions of my meaning, by subjoining a few miscellaneous reinarks and illustrations.

The indiscriminate zeal against hypotheses, so generally avowed at present by the professed followers of Bacon, has been much encouraged by the strong and decided terms in which, on various occasions, they are reprobated by Newton *. But the language of this great man, when he happens to touch upon logical questions, must not always be too literally interpreted. It must be qualified and limited, so as to accord with the exemplifications which he himself has given of his general

Hypotheses non fingo. Quicquid enim ex phenomenis non deducitur hypothesis "vocanda est, et hypotheses, seu metaphysicæ, seu physicæ, seu qualitatum occultarum, seu mechanicæ, in philosophia experimentali locum non habent." See the general Scholium at the end of the Principia.

rules. Of the truth of this remark, the passages now alluded to afford a satisfactory proof; for, while they are expressed in the most unconditional and absolute terms, so many exceptions to them occur in his own writings, as to authorize the conclusion, that he expected his readers would of themselves be able to supply the obvious and necessary comments. It is probable that, in these passages, he had more particularly in his the Vortices of Des Cartes.

eye

"The votaries of hypotheses (says Dr Reid) have often "been challenged to shew one useful discovery in the works of "nature that was ever made in that way." In reply to this challenge, it is sufficient, on the present occasion, to mention the theory of Gravitation, and the Copernican system. Of the former, we have the testimony of Dr Pemberton, that it took its first rise from a conjecture or hypothesis suggested by analogy; nor indeed could it be considered in any other light, till that period in Newton's life, when, by a calculation founded on the accurate measurement of the earth by Picard, he evinced the

Essays on the Intellectual Powers of Man, p. 88. 4to Edit. In another part of the same volume, the following assertion occurs. "Of all the discoveries that have been "made concerning the inward structure of the human body, never one was made by "conjecture. The same thing may be said, with justice, of every other part of the "works of God, wherein any real discovery has been made. Such discoveries have "always been made by patient observation, by accurate experiments, or by conclusions "drawn by strict reasoning from observations and experiments; and such discoveries "have always tended to refute, but not to confirm, the theories and hypotheses which " ingenious men had invented." Ibid. p. 49.

+ See Note (R.)

coincidence between the law which regulates the fall of heavy bodies, and the power which retains the Moon in her orbit. The Copernican system, however, furnishes a case still stronger, and still more directly applicable to our purpose; inasmuch as the only evidence which the author was able to offer in its favour, was the advantage which it possessed over every other hypothesis, in explaining, with simplicity and beauty, all the phenomena of the heavens. In the mind of Copernicus, therefore, this system was nothing more than a hypothesis;—but it was a hypothesis conformable to the universal analogy of nature, always accomplishing her ends by the simplest "C'est pour la simplicité (says Bailly) que Copernic "replaça le soleil au centre du monde; c'est pour elle que Kepler va détruire tous les épicycles que Copernic avoit "laissés subsister: peu de principes, de grands moyens en petit nombre, des phénomènes infinis et variés, voilà le ta"bleau de l'univers *."

means.

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* Histoire de l'Astronomie Moderne, Tome II. p. 2.

From this anticipation of simplicity in the laws of nature (a logical principle not less universally recognized among ancient than among modern philosophers), Bailly has drawn an argument in support of his favourite hypothesis concerning the origin of the sciences. His words are these: "La simplicité n'est pas essentiellement un principe, un "axiôme, c'est le résultat dés travaux; ce n'est pas une idée de l'enfance du monde, elle "appartient à la maturité des hommes; c'est la plus grande des vérités que l'observation "constante arrache à l'illusion des effets: ce ne peut être qu'un reste de la science pri"mitive. Lorsque chez un peuple, possesseur d'une mythologie compliquée, et qui n'a "d'autre physique que ces fables, les philosophes, voulant réduire la nature à un seul principe, annonceront que l'eau est la source de toutes choses, ou le feu l'agent univer"sel, nous dirons à ces philosophes: vous parlez une langue que n'est pas la vôtre; vous avez saisi par un instinct philosophique ces vérités au-dessus de votre siècle, de votre

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According to this view of the subject, the confidence which we repose in Analogy rests ultimately on the evidence of Experience; and hence, an additional argument in favour of the former method of investigation, when cautiously followed; as well as an additional proof of the imperceptible shades by which Experience and Analogy run into each other.

Nor is the utility of hypothetical theories confined to those cases in which they have been confirmed by subsequent researches it may be equally great, where they have com

"nation, et de vous-mêmes; c'est la sagesse des anciens qui vous a été transmise "dition," &c. &c. &c.—Ibid, p. 4.

par tra

To the general remark which introduces this passage I readily subscribe. The confidence with which philosophers anticipate the simplicity of Nature's laws is unquestionably the result of experience, and of experience alone; and implies a far more extensive knowledge of her operations than can be expected from the uninformed multitude. The inference, however, deduced from this, by the ingenious and eloquent, but sometimes too fanciful historian, is not a little precipitate. The passion for excessive simplification, so remarkably exemplified in the physical systems of the Greeks, seems to be sufficiently accounted for by their scanty stock of facts, combined with that ambition to explain every thing from the smallest possible number of data, which, in all ages of the world, has been one of the most common infirmities of genius. On the other hand, the principle in question, when stated in the form of a proposition, is of so abstract and metaphysical a nature, that it is highly improbable it should have survived the shock of revolutions which had proved fatal to the memory of particular discoveries. The arts, it has been frequently observed, are more easily transmitted by mere tradition, from one generation to another, than the speculative sciences; and, for a similar reason, physical systems are far less likely to sink into oblivion, than abstract maxims, which have no immediate reference to objects of sense, or to the ordinary concerns of life.

pletely disappointed the expectations of their authors. Nothing, I think, can be juster than Hartley's remark, that

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any hypothesis which possesses a sufficient degree of plausibility to account for a number of facts, helps us to digest "these facts in proper order, to bring new ones to light, and "to make experimenta crucis for the sake of future inquirers *." Indeed, it has probably been in this way that most discoveries have been made; for although a knowledge of facts must be prior to the formation of a legitimate theory; yet a hypothetical theory is generally the best guide to the knowledge of connected and of useful facts.

The first conception of a hypothetical theory, it must always be remembered, (if the theory possesses any plausibility whatever) presupposes a general acquaintance with the phenomena which it aims to account for; and it is by reasoning synthetically from the hypothesis, and comparing the deductions with observation and experiment, that the cautious inquirer is gradually led, either to correct it in such a manner as to reconcile it with facts, or finally to abandon it as an unfounded conjecture. Even in this latter case, an approach is made to the truth in the way of exclusion; while, at the same time, an accession is gained to that class of associated and kindred phenomena, which it is his object to trace to their parent stock.

• Observations on Man, Chap. i. Prop. v.

✦ "Illud interim monemus; ut nemo animo concidat, aut quasi confundatur, si expe