[6] If any one should be disposed to do so, I can only reply to him in the words of Professor Huxley, who puts the case tersely and well:—“What is the value of the evidence which leads one to believe that one’s fellow-man feels? The only evidence in this argument from analogy is the similarity of his structure and of his actions to one’s own, and if that is good enough to prove that one’s fellow-man feels, surely it is good enough to prove that an ape feels,” etc. (Critiques and Addresses, p. 282). To this statement of the case Mr. Mivart offers, indeed, a criticism, but it is one of a singularly feeble character. He says, “Surely it is not by similarity of structure or actions, but by language that men are placed in communication with one another.” To this it seems sufficient to ask, in the first place, whether language is not action; and, in the next, whether, as expressive of suffering, articulate speech is regarded by us as more “eloquent” than inarticulate cries and gestures?
[7] Of course where the term Reason is intended to signify Introspective Thought, the above remarks do not apply, further than to indicate the misuse of the term.
[8] I here neglect to consider the view of Bishop Butler, and others who have followed him, that animals may have an immortal principle as well as man; for, if this view is maintained, it serves to identify, not to separate, human and brute psychology. The dictum of Aristotle and Buffon, that animals differ from man in having no power of mental apprehension, may also be disregarded; for it appears to be sufficiently disposed of by the following remark of Dureau de la Malle, which I here quote as presenting some historical interest in relation to the theory of natural selection. He says: “Si les animaux n’étaient pas suscéptibles d’apprendre les moyens de se conserver, les espèces se seraient anéanties.”
[9] John Fiske, Excursions of an Evolutionist, pp. 42, 43 (1884).
[10] Natural Selection, p. 343. It will subsequently appear, as a general consequence of our investigation of savage psychology, that of these two opposite opinions the one advocated by Mr. Mivart is best supported by facts. But I may here adduce one or two considerations of a more special nature bearing upon this point. First, as to cerebral structure, the case is thus summed up by Professor Huxley:—“The difference in weight of brain between the highest and the lowest man is far greater, both relatively and absolutely, than that between the lowest man and the highest ape. The latter, as has been seen, is represented by, say 12 ounces of cerebral substance absolutely, or by 32:20 relatively; but, as the largest recorded human brain weighed between 65 and 66 ounces, the former difference is represented by more than 33 ounces absolutely, or by 65:32 relatively. Regarded systematically, the cerebral differences of man and apes are not of more than generic value—his family distinction resting chiefly on his dentition, his pelves, and his lower limbs” (Man’s Place in Nature, p. 103). Next, concerning cerebral function, Mr. Chauncey Wright well remarks:—“A psychological analysis of the faculty of language shows that even the smallest proficiency in it might require more brain power than the greatest proficiency in any other direction” (North American Review, Oct. 1870, p. 295). After quoting this, Mr. Darwin observes of savage man, “He has invented and is able to use various weapons, tools, traps, &c., with which he defends himself, kills or catches prey, and otherwise obtains food. He has made rafts or canoes for fishing, or crossing over to neighbouring fertile islands. He has discovered the art of making fire.... These several inventions, by which man in the rudest state has become so preeminent, are the direct results of the development of his powers of observation, memory, curiosity, imagination, and reason. I cannot, therefore, understand how it is that Mr. Wallace maintains that ‘natural selection could only have endowed the savage with a brain a little superior to that of an ape’” (Descent of Man, pp. 48, 49).
[11] The Human Species, English trans., p. 22.
[12] Sundry other and still more special distinctions of a psychological kind have been alleged by various writers as obtaining between man and the lower animals—such as making fire, employing barter, wearing clothes, using tools, and so forth. But as all these distinctions are merely particular instances, or detailed illustrations, of the more intelligent order of ideation which belongs to mankind, it is needless to occupy space with their discussion. Here, also, I may remark that in this work I am not concerned with the popular objection to Darwinism on account of “missing-links,” or the absence of fossil remains structurally intermediate between those of man and the anthropoid apes. This is a subject that belongs to palæontology, and, therefore, its treatment would be out of place in these pages. Nevertheless, I may here briefly remark that the supposed difficulty is not one of any magnitude. Although to the popular mind it seems almost self-evident that if there ever existed a long series of generations connecting the bodily structure of man with that of the higher apes, at least some few of their bones ought now to be forthcoming; the geologist too well knows how little reliance can be placed on such merely negative testimony where the record of geology is in question. Countless other instances may now be quoted of connecting links having been but recently found between animal groups which are zoologically much more widely separated than are apes and men. Indeed, so destitute of force is this popular objection held to be by geologists, that it is not regarded by them as amounting to any objection at all. On the other hand, the close anatomical resemblance that subsists between man and the higher apes—every bone, muscle, nerve, vessel, etc., in the enormously complex structure of the one coinciding, each to each, with the no less enormously complex structure of the other—speaks so voluminously in favour of an uninterrupted continuity of descent, that, as before remarked, no one who is at all entitled to speak upon the subject has ventured to dispute this continuity so far as the corporeal structure is concerned. All the few naturalists who still withhold their assent from the theory of evolution in its reference to man, expressly base their opinion on those grounds of psychology which it is the object of the present treatise to investigate.
[13] In my previous work I devoted a chapter to “Imagination,” in which I treated of the psychology of ideation so far as animals are concerned. It is now needful to consider ideation with reference to man; and, in order to do this, it is further needful to revert in some measure to the ideation of animals. I will, however, try as far as possible to avoid repeating myself, and therefore in the three following chapters I will assume that the reader is already acquainted with my previous work. Indeed, the argument running through the three following chapters cannot be fully appreciated unless their perusal is preceded by that of chapters ix. and x. of Mental Evolution in Animals.
[14] Human Understanding, bk. ii., chap. ii., 10, 11. To this passage Berkeley objected that it is impossible to form an abstract idea of quality as apart from any concrete idea of object; e.g. an idea of motion distinct from that of any body moving. (See Principles of Human Knowledge, Introd. vii.-xix.). This is a point which I cannot fully treat without going into the philosophy of the great discussion on Nominalism, Realism, and Conceptualism—a matter which would take me beyond the strictly psychological limits within which I desire to confine my work. It will, therefore, be enough to point out that Berkeley’s criticism here merely amounts to showing that Locke did not pursue sufficiently far his philosophy of Nominalism. What Locke did was to see, and to state, that a general or abstract idea embodies a perception of likeness between individuals of a kind while disregarding the differences; what he failed to do was to take the further step of showing that such an idea is not an idea in the sense of being a mental image; it is merely an intellectual symbol of an actually impossible existence, namely, of quality apart from object. Intellectual symbolism of this kind is performed mainly through the agency of verbal or other conventional signs (as we shall see later on), and it is owing to a clearer understanding of this process that Realism was gradually vanquished by Nominalism. The only difference, then, between Locke and Berkeley here is, that the nominalism of the former was not so complete or thorough as that of the latter. I may remark that if in the following discussion I appear to fail in distinctly setting forth the doctrine of nominalism, I do so only in order that my investigation may avoid needless collision with conceptualism. For myself I am a nominalist, and agree with Mill that to say we think in concepts is only another way of saying that we think in class names.
[15] This simile has been previously used by Mr. Galton himself, and also by Mr. Huxley in his work on Hume.