bi)ity or possible co-suggestion (all thoughts of the same mental subject are associable, or capable of suggesting each other) ; (2.) Repetition or direct remembrance (thoughts coidentical in modification, but differing in time, tend to suggest each other) : (3.) Redintegration, direct remembrance or reminiscence (thoughts once coidentical in time, are, however, different as mental modes, again suggestive of each other, and that in the mutual order which they originally held) ; (4.) Preference (thoughts are suggested not merely by force of the general subjective relation subsisting between themselves, they are also suggested in proportion to the relation of interest, from whatever source, in which they stand to the individual mind). Upon these follow, as special laws : A, Primary modes of the laws of Repetition and Redintegration (1), law of Similars (Analogy, Affinity) ; (2), law of Contrast ; (3), law of Coadjacency (Cause and Effect, &c.) ; B, Secondary modes of the law of Preference, under the law of Possibility (1), laws of Immediacy and Homogeneity ; (2), law of Facility. Such is the scheme ; and now may be understood what interpretation Hamilton desires to put upon Aristotle s doctrine, when he finds or seeks in it a parallel relation to that established by himself between the general laws, more especially Redintegration, and his special ones. But, though the commentary of The- mistius, which he cites, lends some kind of support to the position, it cannot be maintained without putting the greatest strain on Aristotle s language, and in one place it is as good as surrendered by Hamilton himself (footnote, p. 900, b). Nor is the ascription of such a meaning at all necessary to establish Aristotle s credit as regards the
doctrine of mental association.Thus far the principles of association have been con sidered only as involved in mental reproduction and repre sentation. There has grown up, however, especially in England, the psychological school above mentioned, which aims at explaining all mental acquisitions, and the more complex mental processes generally, under laws not other than those determining simple reproduction. Hamilton also, though professing, in the title of his outline just noticed, to deal with reproduction only, formulates a num ber of still more general laws of mental succession law of Succession, law of Variation, law of Dependence, law of Relativity or Integration (involving law of Conditioned), and, finally, law of Intrinsic or Objective Relativity as the highest to which human consciousness is subject ; but it is in a sense quite different that the psychologists of the so-called Associationist School intend their appropriation of the principle or principles commonly signalised. As far as can be judged from imperfect records, they were antici pated to some extent by the experientialists of ancient times, both Stoic and Epicurean (cf. Diogenes Laertius, as above). In the modern period, Hobbes is the first thinker of permanent note to whom the doctrine may be traced. Though he took, as has been seen, anything but an exhaustive view of the phenomena of mental succession, yet, after dealing with trains of imagination, or what he called mental discourse, he sought in the higher depart ments of intellect to explain reasoning as a discourse in words, dependent upon an arbitrary system of marks, each associated with, or standing for, a variety of imaginations ; and, save for a general assertion that reasoning is a reckoning otherwise, a compounding and resolving he had no other account of knowledge to give. The whole emotional side of mind, or, in his language, the passions, he, in like manner, resolved into an expectation of con sequences based on past experience of pleasures and pains of sense. Thus, though he made no serious attempt to justify his analysis in detail, he is undoubtedly to be classed with the associationists of the next century Hartley and the others. They, however, were wont to trace the first beginnings of their psychological theory no farther back than to Locke s Essay. If this seems strange, when Locke did little more than supply them with the word Association, it must be remembered in what ill repute the name of Hobbes stood, and also that Locke s work, though not directly concerned with the question of psychological development, being rather of metaphysical or logical import, was eminently psychological in spirit, and might fairly be held to contain in an implicit form the principle or principles evolved later by the associationists. Berkeley, dealing, immediately after Locke and altogether in Locke s spirit, with the special psychological problem of visual perception, was driven to posit expressly a principle of suggestion or association in these terms : " That one idea may suggest another to the mind, it Avill suffice that they have been observed to go together, without any demonstra tion of the necessity of their coexistence, or so much as knowing what it is that makes them so to coexist " (New Theory of Vision, 25) ; and to support the obvious applica tion of the principle to the case of the sensations of sight and touch before him, he constantly urged that association of sound and sense of language which the later school has always put in the foreground, whether as illustrating the principle in general or in explanation of the supreme importance of language for knowledge. It was natural, then, that Hume, coming after Berkeley, and assuming Berkeley s results, though he reverted to the larger inquiry of Locke, should be more explicit in his reference to association ; and, not only explicit, he was original also, when he spoke of it as a " kind of attraction which in the mental world will be found to have as extraordinary effects as in the natural, and to show itself in as many and as various forms " (Human Nature, i. 1, 4). Other inquirers were, in fact, appearing about the same time, who con ceived of association with this breadth of view, and set themselves to track, as psychologists, its effects in detail.
years after the Human Nature, and one year after the better-known Inquiry, of Hume), opened the path for all the investigations of like nature that have since that time become so characteristic of the English name in psychology. According to his own statement, his attention was first turned to the subject about eighteen years before, through what he heard of an opinion of the " Rev. Mr Gay," that it was possible to deduce all our intellectual pleasures and pains from association. Gay is known only by a disserta tion on the fundamental principles of virtue, prefixed, at first anonymously, in 1731, to Archdeacon (afterwards Bishop) Law s translation of King s Origin of Evil, wherein it was maintained, with considerable force, that by associa tion the feelings belonging to ends may come to attach themselves to means, and give rise to action for the means as if they were ends, as seen (the instance has become a commonplace) in the passion for money-making. In this vein, but on a very different scale, Hartley proceeded to work. A physician by profession, and otherwise well versed in science, he sought to combine with an elaborate theory of mental association a minutely detailed hypothesis as to the corresponding action of the nervous system, based upon the suggestion of a vibratory motion within the nerves thrown out by Newton in the last paragraph of the Principia. So far, however, from promoting the acceptance of the psychological theory, this physical hypothesis proved to have rather the opposite effect, and it began to bo dropped by Hartley s followers (as Priestley, in his abridged edition of the Observations, 1775) before it was seriously impugned from without. "When it is studied in the original, and not taken upon the report of hostile critics, who Tvould not, or could not at all events, who did not
understand it, no little importance must still be accorded to