"When two phenomena have been very often experienced in conjunction,
and have not, in any single instance, occurred separately either in
experience or in thought, there is produced between them what has been
called inseparable, or, less correctly, indissoluble, association; by
which is not meant that the association must inevitably last to the
end of life--that no subsequent experience or process of thought can
possibly avail to dissolve it; but only that as long as no such
experience or process of thought has taken place, the association is
irresistible; it is impossible for us to think the one thing disjoined
from the other."--(_Examination of Hamilton's Philosophy_, 2nd ed. p.
191.)
It is chiefly by J.S. Mill that the philosophical application of the
principle has been made. The first and most obvious application is to
so-called necessary truths--such, namely, as are not merely analytic
judgments but involve a synthesis of distinct notions. Again, the same
thinker sought to prove Inseparable Association the ground of belief
in an external objective world. The former application, especially, is
facilitated, when the experience through which the association is
supposed to be constituted is understood as cumulative in the race,
and transmissible as original endowment to individuals--endowment that
may be expressed either, subjectively, as latent intelligence, or,
objectively, as fixed nervous connexions. Spencer, as before
suggested, is the author of this extended view of mental association.
_Modern Criticism._--Of recent years the associationist theory has
been subjected to searching criticism, and it has been maintained by
many writers that the laws are both unsatisfactorily expressed and
insufficient to explain the facts. Among the most vigorous and
comprehensive of these investigations is that of F.H. Bradley in his
_Principles of Logic_ (1883). Having admitted the psychological fact
of mental association, he attacks the theories of Mill and Bain
primarily on the ground that they purport to give an account of mental
life as a whole, a metaphysical doctrine of existence. According to
this doctrine, mental activity is ultimately reducible to particular
feelings, impressions, ideas, which are disparate and unconnected,
until chance Association brings them together. On this assumption the
laws of Association naturally emerge in the following form:--(1) The
_law of Contiguity._--"Actions, sensations and states of feeling,
occurring together or in close connexion, 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 be brought up in idea"
(A. Bain, _Senses and Intellect_, p. 327). (2) The _law of
Similarity._--"Present actions, sensation, thoughts or emotions tend
to revive their like among previous impressions or states" (A. Bain,
_ibid._ 457. Compare J.S. Mill, _Logic_, ii. p. 440, 9th ed.). The
fundamental objection to (1) is that ideas and impressions once
experienced do not recur; they are particular existences, and, as
such, do not persevere to recur or be presented. So Mill is wrong in
speaking of two impressions being "frequently experienced." Bradley
claims thus to reduce the law to "When we have experienced (or even
thought of) several pairs of impressions (simultaneous or successive),
which pairs are like one another; then whenever an idea occurs which
is like all the impressions on one side of these pairs, it tends to
excite an idea which is like all the impressions on the other side."
This statement is destructive of the title of the law, because it
appears that what were contiguous (the impressions) are not
associated, and what are associated (the ideas) were not contiguous;
in other words, the association is not due to contiguity at all.
Proceeding to the law of Similarity (which in Mill's view is at the
back of association by contiguity), and having made a similar
criticism of its phrasing, Bradley maintains that it involves an even
greater absurdity; if two ideas are to be recognized as similar, they
must both be present in the mind; if one is to call up the other, one
must be absent. To the obvious reply that the similarity is recognized
_ex post facto_, and not while the former idea is being called up,
Bradley replies simply that such a view reduces the law to the mere
statement of a phenomenon and deprives it of any explanatory value,
though he hardly makes it clear in what sense this necessarily
invalidates the law from a psychological point of view. He further
points out with greater force that in point of fact mere similarity is
not the basis of ordinary cases of mental reproduction, inasmuch as in
any given instance there is more difference than similarity between
the ideas associated.
Bradley himself bases association on identity plus contiguity:--"Any
part of a single state of mind tends, if reproduced, to re-instate the
remainder," or "any element tends to reproduce those elements with
which it has formed one state of mind." This law he calls by the name
"redintegration," understood, of course, in a sense different from
that in which Hamilton used it. The radical difference between this
law and those of Mill and Bain is that it deals not with particular
units of thoughts but with universals or identity between individuals.
In any example of such reproduction the universal appears in a
particular form which is more or less different from that in which it
originally existed.
_Psychophysical Researches._--Bradley's discussion deals with the
subject purely from the metaphysical side, and the total result
practically is that association occurs only between universals. From
the point of view of empirical psychologists Bradley's results are
open to the charge which he made against those who impugned his view
of the law of similarity, namely that they are merely a statement--not
in any real sense an explanation. The relation between the mental and
the physical phenomena of association has occupied the attention of
all the leading psychologists (see PSYCHOLOGY). William James holds
that association is of "objects" not of "ideas," is between "things
thought of"--so far as the word stands for an effect. "So far as it
stands for a cause it is between processes in the brain." Dealing with
the law of Contiguity he says that the "most natural way of accounting
for it is to conceive it as a result of the laws of habit in the
nervous system; in other words to ascribe it to a physiological
cause." Association is thus due to the fact that when a nerve current
has once passed by a given way, it will pass more easily by that way
in future; and this fact is a physical fact. He further seeks to
maintain the important deduction that the only primary or ultimate law
of association is that of neural habit.
The objections to the associationist theory are summed up by G.F.
Stout (_Analytic Psychol._, vol. ii. pp. 47 seq.) under three heads.
Of these the first is that the theory as stated, e.g. by Bain, lays
far too much stress on the mere connexion of elements hitherto
entirely separate; whereas, in fact, every new mental state or
synthesis consists in the development or modification of a
pre-existing state or psychic whole. Secondly, it is quite false to
regard an association as merely an aggregate of disparate units; in
fact, the _form_ of the new idea is quite as important as the elements
which it comprises. Thirdly, the phraseology used by the
associationists seems to assume that the parts that go to form the
whole retain their identity unimpaired; in fact, each part or element
is _ipso facto_ modified by the very fact of its entering into such
combination.
The experimental methods now in vogue have to a large extent removed
the discussion of the whole subject of association of ideas, depending
in the case of the older writers on introspection, into a new sphere.
In such a work as E.B. Titchener's _Experimental Psychology_ (1905),
association is treated as a branch of the study of mental reactions,
of which association reactions are one division.
BIBLIOGRAPHY.--See PSYCHOLOGY; and the works of Bradley, Stout, and
James, above quoted, and general works on psychology: articles in
_Mind_ (passim); A. Bain, _Senses and Intellect_ (4th ed., 1894), and
in _Mind_, xii. (1887) pp. 237-249; John Watson, _An Outline of
Philosophy_ (1898); H. Hoffding, _Hist. of Mod. Philos._ (Eng. trans.,
Lond., 1900), _Psychologie in Umrissen auf Grundlage der Erfahrung_
(2nd ed., Leipzig, 1893); Jas. Sully, _The Human Mind_ (1892), and
_Outlines of Psych._ (Lond., 1892); E.B. Titchener, _Outline of
Psych._ (New York, 1896), and in his trans. of O. Kulpe's _Outlines of
Psych._ (New York, 1895,); Jas. Ward in _Mind_, viii. (1883), xii.
(1887), new series ii. (1893), iii. (1894); G.T. Ladd, _Psychology,
Descriptive and Explanatory_ (Lond., 1894); C.L.C. Morgan, _Introd. to
Comparative Psych._ (Lond., 1894); W. Wundt, _Princip. of Physiol.
Psych._ (Eng. trans., 1904), _Human and Animal Psych._ (Eng. trans.,
1894), pp. 282-307; _Outlines of Psych._ (Eng. trans., 1897); E.
Claparede, _L'Association des idees_ (1903). For associationism in
Greek philosophy see J.I. Beare, _Greek Theories of Elementary
Cognition_ (Oxford, 1906), part iii. SS 14, 43 seq.