If there has been no better known a, b, c, it is evident that the mere generalisation of new facts d, e, f, will not add anything to our knowledge of them. In deduction we should only return to them the knowledge just extracted from them. We should be explaining things by themselves—reasoning in a circle[12].
The unity, which explains is not the general idea. It is a unity of function or service, and may include things utterly heterogeneous, and therefore incapable of being reduced to a common idea. The pen in my hand consists of wood and metal; if I generalise them into Matter—the nearest class that includes both—I do not thereby explain the pen. But it is explained by the unity of service: the wood and metal contribute to form one instrument for writing.
The best results of modern science are discoveries of utilities (inventions); discoveries of the relations of sequence among objects, which enable us to predict their arrival years in advance; of coexistences on the great cosmic scale (geographical and stellar exploration); of co-inherence of properties in individual objects (chemistry). Yet science is still too generalistic. It runs too much to classification and nomenclature, which is nothing but memoria technica. Modern biology presents a curious return of Platonism. The general idea is not indeed put forward as the cause of individuals, but a particular concrete animal is found who closely resembles the general idea, and it is imagined that an animal like him was the original cause of all animals of his species. When it happens—as it occasionally must in a thorough-going system of phenomenal classification—that the average or general idea falls between two species, no individual can be found to represent it with the desired exactness. In this case it is supposed by evolutionists that the intermediate animal has existed but is now extinct. These are the 'missing links' so badly wanted to complete the evolutionary scheme.
[10:] 'Mysticism is neither more nor less than ascribing objective existence to the subjective creations of our own faculties, to ideas or feelings of the mind.'—Logic, chapter on 'Fallacies.'
[11:] With equal plausibility it might be argued that we have no particular ideas, because it is difficult if not impossible to observe and remember all the details of any object. Our most particular ideas are slightly abstract, and in the process of forgetting they become more and more abstract, until they disappear altogether.
[12:] Mill's nominalistic tendencies led him to the same conclusion: 'Our general ideas contain nothing but what has been put into them, either by our passive experience, or by our active habits of thought; and the metaphysicians in all ages, who have attempted to construct the laws of the universe by reasoning from our supposed necessities of thought, have always proceeded, and only could proceed, by laboriously finding in their own minds what they themselves had formerly put there, and evolving from their ideas of things what they had first involved in those ideas.'—Logic, Bk. V. c. 3. § 3.
IMAGINATION
XVI
This faculty or habit consists essentially in combining ideas (particular or general), or objects and ideas, so as to form systems different from those occurring in actual experience. The whole has never been perceived, though all its elements have been perceived.
Any association of ideas may be called imaginary if it occurs in an order different from the order of experience. But the term Imagination is properly confined to novel combinations deliberately and consciously formed to serve some utility. It is thus distinguished from Reverie, in which no choice or control enters into the recollection.