A Beginner's History of Philosophy, Vol. 2: Modern Philosophy

by Herbert Ernest Cushman

The Association of Ideas. Since nothing can enter the mind except through the two portals of outer and inner impressions, every idea in the mind is the copy of one or several impressions. How then can there be any such thing as error? Error arises from the understanding and imagination in their manipulation of the impressions—from the faculties of the mind combining, separating, and transposing the impressions and their memories. An idea resulting from such transposition may and often is referred to an impression different from the one of which it is the copy.

What does Hume mean by the faculties and powers of the mind? He does not mean that the mind with its functions exists as a reality, since all that exist are impressions and the copies of impressions or ideas. Hume means by mental faculties and powers the various modes by which ideas combine. Hume makes no distinction between memory, imagination, judgment, conception, etc., except (1) as different groupings of ideas and (2) as accompanied by different feelings. The whole mental life and the faculties of the mental life are nothing but an association of ideas. Isolated ideas are explained as copies of isolated impressions; and from these ideas are derived groups of ideas which we call trains of thought. Why do ideas group themselves together? The only answer is that it is the nature of ideas. Hume frequently speaks of these associative relations as “the manner of conceiving ideas.” He also says that there is a “gentle force” or “determination”of the ideas to relate themselves with other ideas. Given the impressions and their relations, and Hume will explain the whole knowing process. Associative relations take an important place in Hume’s theory, but some critics say that they are interlopers; that he has introduced them by a back door; that they are not mentioned in his psychological inventory.

But to Hume there is nothing mysterious about the association of ideas. They are combined, transposed, augmented, and diminished according to fixed rules under mechanical laws. Their relationship takes place without freedom. Impressions occur in the way they happen to occur. Ideas combine in the way they happen to combine. Relations between ideas are accidental and external. There is only one quality of ideas that does not depend on its accidental relation to other ideas. This is the quality of non-contradiction. This is the necessary property of an impression. An impression must be what it is, and cannot be conceived as having properties contrary to its own nature. The quality of identity in an impression is intrinsic and necessary.

According to Hume, there are three fundamental ways in which ideas associate, called the three laws of association. (1) There is the law of resemblance or contrast, by which the occurrence of a thing calls up a similar thing or its opposite. Mathematics is based upon this law of the resemblance, the contrariety, and the quantitative relations of ideas. (2) There is the law of contiguity in time and space, by which things happening together in time and space are recalled together. Upon this law are based the descriptive and experimental sciences. (3) There is the law of causation, upon which religion and the metaphysics of the world ofnature are based. The question with Hume is, How is he to explain all these laws of association as derived from impressions? If they cannot be derived from impressions, then his theory that all knowledge is derived from impressions goes to the wall. The Rationalists and even his predecessors, Locke and Berkeley, had conceived mathematical propositions and causation as underived and in the nature of things. If Hume is to establish his doctrine of complete sensational empiricism, here is his test.

These associations, and not isolated impressions, are the objects of human interest, inquiry, and investigation. Hume makes a further reduction of associations by his well-known classification of them as either “relations of ideas” or “matters of fact.” Associations of contiguity and associations of causation are “matters of fact,” while associations of resemblance are “relations of ideas.” Furthermore, Hume looks upon associations of contiguity as those of outer impressions, associations of resemblance as those of inner impressions, while associations of causation are not what they are alleged to be, but are derived from some inner impressions.

Objects of Knowledge		Matters of Fact		1. Contiguity association	Outer impressions	Descriptive Sciences
				2. Causation association[45]	Inner impressions	Metaphysics
		Relations of Ideas		3. Resemblance association	Inner impressions	Mathematics

The Association of Contiguity. This is the most elementary of the three classes of association, and concerns the spatial and temporal order in which impressionscome to us. Two impressions come at the same time or in succession, and when one of them is remembered, the other is likely to be remembered also. We see a man and hear his name; when we remember the man’s face, we may remember his name also. Hume maintains that this association of succession or coexistence is given with the impressions themselves. It is the order of the outer impressions. We perceive the order of the outer impressions with the same certainty that we perceive the contents of the impressions. This is the only certainty we have about “matters of fact,”—a certainty of the exact order of our immediate outer impressions. We know the order in which our impressions do occur, but, as we shall see, when we argue from this that our impressions must recur in the same order we are involved in a fallacy. Any order may recur. The fact that the sun rises in the east to-day does not make certain that it will rise in the east to-morrow. It is only a matter of probability, however many times repeated. There is no certain science of “matters of fact.”

The Association of Resemblance. This is a clear and distinct association which is given with the impressions. When we have an impression, we see intuitively its similarity or difference to other impressions, and the degrees of likeness and unlikeness. The face of one man reminds us of another man, or we contrast it with a brute’s face. This association concerns only inner impressions, while the association of contiguity concerns outer impressions. This has to do with the “relation of ideas,” while the association of contiguity has to do with “matters of fact.”

1. Mathematics. But there is this difference between the association of resemblance and that of contiguity—upon resemblance is founded a demonstrative science. This is mathematics—the sole demonstrative science. The subject-matter of mathematics consists of the possible relations between the contents of our ideas—the possible relations between our inner impressions. These relations are intuitively known by us, and out of them we get a science of complete certainty. We make a comparison between the magnitudes in the contents of ideas, and we analyze their regularity. This is mathematics, and it is a perfectly legitimate science. Because it confines itself to the relations between ideas, and has nothing to do with “matters of fact,” it can be a demonstrative science. All mathematical knowledge is restricted to the study and verification of ideas, and has therefore nothing to do with the external world.

2. The Conception of Substance: Hume’s Attack on Theology. But the association of resemblance has been made the basis of a common illusion. It has been made to transcend its proper sphere of a relationship among inner impressions; and resemblance between ideas has been taken by people generally to mean metaphysical identity or substance. It has been transformed from a relationship between ideas to a relationship between “matters of fact.” Now substance is evidently not an association given with the impressions, like their temporal and spatial order in the association of contiguity, nor is it mere impression of resemblance. Substance is the conception of an unknown, indescribable something back of impressions. There is the conception of the material substance or matter, and the spiritual substance or the soul. How did such illusory conceptions arise? If Hume rejects them as matters of real knowledge, he must neverthelessexplain their psychological origin. The illusory idea of substance originates from the similarity of the frequent conjoining of certain impressions. The impressions—sweet, rough, white, etc.—occur together so often that the imagination creates the conception of the substance of sugar behind them. This arises not from the first experience, but after the association of impressions has been observed a large number of times. From the frequent association of ideas arises the feeling of their necessary coexistence. Thus do we come to have the idea of a material substance.