Association of Ideas. This is a phrase of great importance in the Philosophy of the Human Mind, as expressing, according to an important school of modern thinkers, the most pervading fact at the foundation of our intelligence. What is meant by Association of Ideas, may be thus illustrated: When we see the sky becoming overcast, we think of rain as about to follow, the notion of rain not having previously been present to our mind. When we hear the church-bells, we are apt to think of the crowds in the street, or of some of the other circumstances of public worship. When we pass a house, we are reminded of its occupier; and meeting a person we know, we may be carried in thought to his office, and from that to other persons holding the same office, and so on. If an object is before our eyes, as a mountain, we are said to receive an impression or sensation of it, in consequence of the actual presence of the thing; but it is possible for us to remember the mountain, or to have an idea of it, when far away from the reality, in which case there must be some power in the mind itself, different from the susceptibility to present objects, a power of retaining, reviving, or resuscitating those states at first induced by contact with the actual. Besides the sights, and sounds, and touches caused by contact with real things, we are greatly occupied with sights, sounds, and touches remembered, anticipated, or imagined, which is to live in a world of ideas; and it is in this world that the process termed Association has its sphere. The association between names and things comprehends one of the most extensive applications of the power in question.
The circumstances under which one idea brings forward another into the view are principally these two—viz. first, previous proximity; and second, likeness. The terms 'Contiguity' and 'Similarity' may be used to express them. The first is exemplified in the cases of association given above; for in most of those it will be found that the conjoined notions have been frequently in the view at the same time, in consequence of which they have, as it were, grown together, or become part of the same whole. Thus, we have often noticed the darkened sky followed by a shower; the two facts have occupied the attention simultaneously, and in virtue of some power belonging to our mental framework, they have cohered into an inseparable couple or aggregate in the mind. This is proximity, or contiguity. When one idea suggests another which was never in company with it before, it is generally through the force of some likeness between the two. We meet an old man in the street with a very peculiar face, which reminds us of the bust of Socrates. These two things had never accompanied one another in our mind before, and therefore it could not be the force of proximity that made the second to arise at the instigation of the first; but there was a certain amount of likeness between the old man's features and those of Socrates. Identification and comparison both imply that things are brought together by virtue of their similarity. The principle of proximity operates most in Memory, Habit, and Routine; similarity has to do with invention and originality, and is essential to the processes of Reason and Imagination.
Law of Contiguity.—The principle of association by proximity is not confined to ideas. Our mechanical habits are formed through the very same power of our constitution that enables us to recall or remember ideas. The taught movements of a soldier or of a skilled workman are connected together so firmly that one succeeds to another almost of its own accord. Everything of the nature of acquisition supposes a plastic property in the human system, giving permanent coherence to acts that have been performed together.
The following is a general statement of the law under consideration: Actions, Sensations, States of Feeling, and Ideas, occurring together, or in close succession, tend to grow together, or cohere in such a way that when any one of them is afterwards presented to the mind, the others are apt to arise.
And first, as to association of Actions, or voluntary movements. When we perform a train of movements without any further aid of the will than to commence the series, there must be a fixed connection between each and the one that follows, and this connection may be either instinctive or acquired. There are various cases of instinctive trains, such as the action of the heart, lungs, and intestines, and the movements of deglutition. When a morsel of food reaches the back part of the mouth, the muscles of the throat seize hold of it, and transmit it to the stomach, independent of our will. The connected movements in this case are provided for in the original structure of the nervous and muscular system. In walking, there is partly an instinctive tendency to alternate the limbs, and partly a confirming acquisition, the result of practice. But in those complicated operations that human beings are taught to execute in the various avocations of life, the associating principle is everything. The apparently simple and easy act of taking food is a complicated acquisition; in other words, an extensive group of associated movements, originally built up by slow degrees. A good example of the association of movements is furnished in our acquirement of spoken language, as in committing to memory words, sayings, and passages of books.
When we proceed to Sensations and the Ideas, or subsequent traces, of Sensations, and take along with these the variety of our movements with their ideas, we find an unlimited scope for the associating principle. In the various mechanical acquirements, which include the whole of special handicraft industry and skill, as well as the use of the bodily members in the more general actions of daily life, there may be traced the linkings of actions with actions, or actions with sensations and ideas. The workman fabricating in wood, metal, or stone, acquires a firm connection between each aspect of the material and the muscular power to be applied to bring it one step nearer the desired form. The power of copying anything we see, as in writing, drawing, moulding, &c., when completely mastered, is made up of associations between a visible appearance, and the train of movements calculated to reproduce it. After practice, all this is done, as it is called, mechanically, or without those operations of considering, willing, and remembering directions, that are essential to the learner in a new art. In the greater number of crafts, the eye is the guiding sense to the operator, but not in all. Sometimes it is the ear, as in music. In other arts, the touch is the guiding sense, and in some, as in cookery, the taste and smell direct the operator. Each accomplished workman has in his mind many hundreds, not to say thousands, of couples or aggregates of definite movements with other movements and with sensations, contracted in the course of his apprenticeship to his calling.
If we inquire into the circumstances that favour and promote this extensive circle of acquisitions, we shall find in the first place, a natural activity of temperament to be a good basis of bodily acquirements. Another important circumstance is the acuteness or delicacy of the sense involved in the operation. The third consideration is the natural power of adhesive association belonging to the individual character. The fourth principal circumstance is the interest taken in the work, or the degree to which it engages the feelings of the learner.
A detailed exemplification of this great principle of our nature might be given through all the departments of the human intellect. The acquirements of speech, as already said, contain a wide range of instances. The adhesion of language is partly in the vocal organs, partly in the ear, and partly in the eye, when we come to written and printed characters. The associations of names with things, with actions (as in obeying direction and command), and with other names (in acquiring foreign languages), are a gradual growth favoured by such conditions as the above. The acquirements in Science, Fine Art, and Business, and in everything that constitutes skill or knowledge, proceed upon this plastic property of the mind. It also enlarges the sphere of our pleasures and pains. There are connections established in the mind between our states of feeling and the things that have often accompanied them, so that the accompaniment shall have power to revive the feeling. It is thus that we contract affections, both benevolent and malevolent, towards persons and things, our friends, our home, our country, our property, our pursuits.
Law of Similarity.—This may be expressed as follows: Present Actions, Sensations, Thoughts, and Emotions tend to revive their like among previous impressions.
If the mind worked only by the principle of contiguity, nothing would ever occur to us except in some connection already formed. But some explanation is necessary as to the precise relationship subsisting between the two distinct forces of mental resuscitation, in order to show at once their distinctness and their connection. When the cohesive link between any two contiguous actions, sensations, or ideas is confirmed by a new occurrence or repetition, it is perfectly obvious that the present impression must revive the sum-total of the past impressions, or reinstate the whole mental condition left on the occasion immediately preceding. Thus, if we are disciplining ourselves in the act of drawing a round figure with the hand, any present effort must recall the state of the muscular and nervous action, or the precise bent acquired at the end of the previous effort, while that effort had to restore the condition at the end of the one preceding, and so on. But this reinstatement of a former condition by a present act of the same kind, is really and truly a case of the principle before us, or of like recalling like; and without such recall, the progressive adhesion of contiguous things would be impossible. It would appear, therefore, that similarity is tacitly assumed in the operation of contiguity, and is indispensable to the process by which our acquisitions are gradually built up. Why, then, do we set up the associating force of likeness as something independent and distinct? To answer this question, we must advert to the fact that in those cases where the same impression is deepened by every new repetition, the old and the new are not merely similar, they are identical, and the resuscitation takes place without fail, and as a matter of course. But in going deeper into the explanation of the human intellect, we encounter many classes of similars, where there is not absolute identity, but the mixing up of a certain amount of diversity with the likeness actually existing. The botanist classing together all the plants of the same order, as, for example, the Rosaceæ, has to be struck with the occurrence of certain common characters—viz. the properties that distinguish the order—in the midst of great varieties in all other respects. It is exceedingly important in science, in the business of life, and even in the creations of fine art, that the mind should take cognisance of likeness surrounded by unlikeness; which is the case that renders it necessary to characterise as distinct the associating force now under discussion. In the case of perfect identity between a present and a past impression, the past is recovered, and fused with the present, instantaneously and surely. So quick and certain is the process that we lose sight of it altogether; we are scarcely made aware of the existence of an associating link of similarity under such circumstances. But when we pass from perfect to imperfect or partial identity, we are more readily led to perceive the existence of this link of attraction between similars, for we find that the restoration sometimes does not take place. When in some new presentation of an object, the old familiar form is muffled, obscured, distorted, disguised, or in any way altered, it is just a chance if we recognise it.
The intellectual operations known under the names Classification, Generalisation, Induction, and Deduction, all proceed upon the discovery of likeness among things lying wide asunder in space and time, and very often veiled by diversity. Thus, in order to include in one list all the species of the rose, botanists have had to trace the characters of the genus through its various members, wherever they occur, and under the greatest differences in every other respect. It takes a keen identifying faculty—i.e. a strong natural tendency for the resurrection of like to meet like—to see the resemblance of some of these species to the rest. So in the process termed induction, by which a general law is arrived at by comparing instances of it everywhere, there must be an attraction of similars, in order to bring together in the mind the collection of particulars that the induction is based upon. Many of the greatest discoveries in science have turned on the identification of modes of action never before supposed the same, as when Franklin was struck with the resemblance between the atmospheric thunder and lightning and the phenomena of common electricity.
Another wide field for the operation of the same principle is the region of illustrative comparisons, whereby two things widely remote are brought together, in the view either to elucidate one another, or for the sake of ornament and poetic effect. Most men of genius in literature and poetry have contributed original illustrations, similes, metaphors, or comparisons in the course of their compositions. A mathematician is the most likely person to bring up comparisons from mathematics; a botanist is prepared to identify plants; a travelled man provides illustrations from foreign countries; a historian, from history. The sailor is notoriously rich in nautical similes and illustrations. When any one not specially versed in a subject is yet prone to draw upon it profusely in the way of comparison, we must then refer to great natural endowment as the sole explanation. (For the full treatment of this subject, see Bain on The Senses and the Intellect; Hamilton's Reid; Mill, in his Examination of Hamilton; and the works of Herbert Spencer.)
The earliest known attempt to lay down the laws whereby thought succeeds to thought, is that contained in Aristotle's treatise on Memory. He enumerates three different principles of mental resuscitation—viz. Similarity, Contrariety, and Coadjacency. He has in this been followed by most other philosophers; but it is now generally admitted that contrariety is not an independent associating force. When a thing suggests its opposite or contrary, it will be found that the two have been previously together in the mind, and have therefore acquired a mutual hold by contiguity. Contraries (black and white, health and sickness) have a natural inseparability; they are of the class of relatives like father and son, which imply each other necessarily, and have no meaning except by mutual reference. It requires no new principle of our constitution to account for suggestion in this particular case.
Hobbes recognised the principle of contiguity as the foundation of reminiscence; but the Aristotelian philosopher, Vives, who wrote in the 14th century, was the first to specify in minute detail the various circumstances that determine the adhesive bond of recollection. Hume enumerated resemblance, contiguity, and causation. Causation, however, is merely a case of contiguity; so also we may say of Order in Place, and Order in Time, which have been given as distinct principles.
ASSOCIATIONIST SCHOOL is a name for those psychologists who seek to explain all mental acquirements, and the most complicated intellectual processes, by laws substantially similar to those that determine simple reproduction—by association of ideas. Their position is, of course, strenuously denied by other schools of thought, including especially Kantians and what is often called the a priori school, who affirm that association in the widest sense of the word is inadequate to explain many fundamentally distinct mental processes. The term Association of Ideas was first used by Locke, but in a very limited reference; the most notable representatives of the Associationist School, which is almost exclusively English, are Hobbes, Hume, Hartley, Priestley, James Mill, Professor Bain, Herbert Spencer, and, in France, Condillac. Associationists differ a good deal amongst themselves—some, like Hartley, taking account only of contiguity, Spencer almost solely of similarity, and some insisting on contrast as a distinct principle. The preceding article, positing only two principles, represents Professor Bain's view. Herbert Spencer has moulded his form of the doctrine by his theory of evolution.