It appears to us, then, that the difference between a sound and unsound induction does not lie in this, that the author of the sound induction goes through the process analysed in the second book of the Novum Organum, and the author of the unsound induction through a different process. They both perform the same process. But one performs it foolishly or carelessly; the other performs it with patience, attention, sagacity, and judgment. Now precepts can do little towards making men patient and attentive, and still less towards making them sagacious and judicious. It is very well to tell men to be on their guard against prejudices, not to believe facts on slight evidence, not to be content with a scanty collection of facts, to put out of their minds the idola which Bacon has so finely described. But these rules are too general to be of much practical use. The question is, What is a prejudice? How long does the incredulity with which I hear a new theory propounded continue to be a wise and salutary incredulity? When does it become an idolum specus, the unreasonable pertinacity of a too sceptical mind? What is slight evidence? What collection of facts is scanty? Will ten instances do, or fifty, or a hundred? In how many months would the first human beings who settled on the shores of the ocean have been justified in believing that the moon had an influence on the tides? After how many experiments would Jenner have been justified in believing that he had discovered a safeguard against the small-pox? These are questions to which it would be most desirable to have a precise answer; but unhappily they are questions to which no precise answer can be returned.
We think then that it is possible to lay down accurate rules, as Bacon has done, for the performing of that part of the inductive process which all men perform alike; but that these rules, though accurate, are not wanted, because in truth they only tell us to do what we are all doing. We think that it is impossible to lay down any precise rule for the performing of that part of the inductive process which a great experimental philosopher performs in one way, and a superstitious old woman in another.
On this subject, we think, Bacon was in an error. He certainly attributed to his rules a value which did not belong to them. He went so far as to say, that, if his method of making discoveries were adopted, little would depend on the degree of force or acuteness of any intellect; that all minds would be reduced to one level, that his philosophy resembled a compass or a rule which equalises all hands, and enables the most unpractised person to draw a more correct circle or line than the best draughtsmen can produce without such aid. (1) This really seems to us as extravagant as it would have been in Lindley Murray to announce that everybody who should learn his Grammar would write as good English as Dryden, or in that very able writer,
(1) Novum Organum, Præf. and Lib. 1. Aph. 122.
the Archbishop of Dublin, to promise that all the readers of his Logic would reason like Chillingworth, and that all the readers of his Rhetoric would speak like Burke. That Bacon was altogether mistaken as to this point will now hardly be disputed. His philosophy has flourished during two hundred years, and has produced none of this levelling. The interval between a man of talents and a dunce is as wide as ever; and is never more clearly discernible than when they engage in researches which require the constant use of induction.
It will be seen that we do not consider Bacon’s ingenious analysis of the inductive method as a very useful performance. Bacon was not, as we have already said, the inventor of the inductive method. He was not even the person who first analysed the inductive method correctly, though he undoubtedly analysed it more minutely than any who preceded him. He was not the person who first showed that by the inductive method alone new truth could be discovered. But he was the person who first turned the minds of speculative men, long occupied in verbal disputes, to the discovery of new and useful truth; and, by doing so, he at once gave to the inductive method an importance and dignity which had never before belonged to it. He was not the maker of that road; he was not the discoverer of that road; he was not the person who first surveyed and mapped that road. But he was the person who first called the public attention to an inexhaustible mine of wealth, which had been utterly neglected, and which was accessible by that road alone. By doing so, he caused that road, which had previously been trodden only by peasants and higglers, to be frequented by a higher class of travellers.
That which was eminently his own in his system was the end which he proposed to himself. The end being given, the means, as it appears to us, could not well be mistaken. If others had aimed at the same object with Bacon, we hold it to be certain that they would have employed the same method with Bacon. It would have been hard to convince Seneca that the inventing of a safety-lamp was an employment worthy of a philosopher. It would have been hard to persuade Thomas Aquinas to descend from the making of syllogisms to the making of gunpowder. But Seneca would never have doubted for a moment that it was only by means of a series of experiments that a safety-lamp could be invented. Thomas Aquinas would never have thought that his barbara and baralipton would enable him to ascertain the proportion which charcoal ought to bear to saltpetre in a pound of gunpowder. Neither common sense nor Aristotle would have suffered him to fall into such an absurdity.
By stimulating men to the discovery of new truth, Bacon stimulated them to employ the inductive method, the only method, even the ancient philosophers and the schoolmen themselves being judges, by which new truth can be discovered. By stimulating men to the discovery of useful truth, he furnished them with a motive to perform the inductive process well and carefully. His predecessors had been, in his phrase, not interpreters, but anticipators of nature. They had been content with the first principles at which they had arrived by the most scanty and slovenly induction. And why was this? It was, we conceive, because their philosophy proposed to itself no practical end, because it was merely an exercise of the mind. A man who wants to contrive a new machine or a new medicine has a strong motive to observe accurately and patiently, and to try experiment after experiment. But a man who merely wants a theme for disputation or declamation has no such motive. He is therefore content with premises grounded on assumption, or on the most scanty and hasty induction. Thus, we conceive, the schoolmen acted. On their foolish premises they often argued with great ability; and as their object was “assensum subjugare, non res,” (1) to be victorious in controversy, not to be victorious over nature, they were consistent. For just as much logical skill could be shown in reasoning on false as on true premises. But the followers of the new philosophy, proposing to themselves the discovery of useful truth as their object, must have altogether failed of attaining that object if they had been content to build theories on superficial induction.
Bacon has remarked (2) that in ages when philosophy was stationary, the mechanical arts went on improving. Why was this? Evidently because the mechanic was not content with so careless a mode of induction as served the purpose of the philosopher. And why was the philosopher more easily satisfied than the mechanic? Evidently because the object of the mechanic was to mould things, whilst the object of the philosopher was only to mould words. Careful induction is not at all necessary to the making of a good syllogism. But it is indispensable to the making of a good shoe. Mechanics, therefore, have always been, as far as the range of their humble but useful callings extended, not anticipators but interpreters of nature. And when a philosophy arose, the object of which was to do on a large scale what the mechanic does on a small scale, to
(1) Novum Organum, Lib. 1. Aph. 29.
(2) De Augmentis, Lib. 1.