And thus we reach the principal aim of the present work, which purports, not to reinforce the time-worn dispute as to the nature of abstraction and generalisation, but to pursue these operations step by step in their development, and multiform aspects. Directly we pass beyond pure individual representation we reach an ascending scale of notions which, apart from the general character possessed by all, are extremely heterogeneous in their nature, and imply distinct mental habits. The question so often discussed as to “What takes place in the mind when we are thinking by general ideas?” is not to be disposed of in one definite answer, but finds variable response according to the circumstances. In order to give an adequate reply, the principal degrees of this scale must first be determined. And for this we require an objective notation which shall give them some external, though not arbitrary, mark.
The first distinguishing mark is given by the absence or presence of words. Abstraction and generalisation, with no possible aid from language, constitute the inferior group which some recent writers have designated by the appropriate name of generic images[9]—a term which clearly shows their intermediate nature between the pure image, and the general notion, properly so-called.
The second class, which we have termed intermediate abstraction, implies the use of words. At their lowest stage these concepts hardly rise above the level of the generic image: they can be reduced to a vague schema, in which the word is almost a superfluous accompaniment. At a stage higher the parts are inverted: the representative schema becomes more and more impoverished, and is obliterated by the word, which rises in consciousness to the first rank.
Finally, the third class, that of the higher concepts, has for its distinguishing mark that it can no longer be represented. If any image arises in consciousness it does not sensibly assist the movement of thought, and may even impede it. Everything, apparently at least, is subordinated to language.
This enumeration of the stages of abstraction can for the present only be given roughly and broadly. Every phase of its evolution should be studied in itself, and accurately determined by its internal and external characteristics. As to the legitimacy, the objective and practical value, of this schematic distribution, nothing less than a detailed exploration from one end to the other of our subject, can confirm or overthrow it.
We shall begin, then, with the lower forms, dwelling upon these at some length, because they are usually neglected, or altogether omitted. This is the pre-linguistic period of abstraction and generalisation: words are totally wanting; they are an unknown factor. How far is it possible without the aid of language to transcend the level of perception, and of consecutive images, and to attain a more elevated intellectual standpoint? In replying empirically, we have three fairly copious sources of information: animals, children who have not yet acquired speech, and uneducated deaf-mutes.
ANIMALS.
It is a commonplace to say that animal psychology is full of obscurities and difficulties. These arise mainly with regard to the question now occupying us; for we are concerned with ascertaining, not whether animals perceive, remember, and even, when their organisation is sufficiently advanced, imagine (which no one denies), but if they are capable in the intellectual order of still better and greater achievements. The common opinion is in the negative; yet this may rest entirely upon ambiguity of language. Without prejudging anything, we must interrogate the facts to hand, and link them as closely as possible in our interpretation.
As to the facts themselves we may be sparing of detail; they are to be found in special treatises, and it is superfluous to repeat them in these pages. It is moreover evident that a large portion of the animal kingdom may be neglected. In its lowest regions it is so remote from us, and has so obscure and scant a psychology, that nothing can be learned from it. In the higher forms alone can we have any chance of finding what we seek, i. e., (1) equivalents of concepts, (2) processes comparable with reasoning.