Context

Having completed his basic classification of ideas, the author turns to the way in which ideas are related to one another. In this section, he discovers a principle that describes how the human mind relates its ideas.

Background

As we saw in the notes on Section 1, the author followed Locke in distinguishing between simple and complex ideas. In the Essay, Book II, Chapter 12, “Complex Ideas,” Locke describes a power of the human understanding to consider several simple ideas “united together as one idea.” He describes complex ideas as being “joined together” or “put together.” This power allows the mind to “make new complex [ideas], which it never received so united,” yet the ultimate materials of which complex ideas are composed are simple ideas.

Despite the potentially infinite number complex ideas the mind may make, there are only three kinds to which all complex ideas “may be reduced.” These are modes, substances, and relations—a division followed by the author. The idea of a mode is that of something which depends on or is an affection of a substance or substances, such as triangle, gratitude, and murder. The ideas of substances consist of “such combinations of simple ideas as are taken to represent distinct particular things subsisting by themselves,” such as a man or an army of men. Ideas of relation “consist in the consideration and comparing one idea with another.” No examples are given here, but in later chapters, Locke gives a detailed treatment of cause and effect, and identity and diversity. We shall consider these kinds of relations in more detail in subsequent sections.

While Locke describes the specific kinds of complex ideas at some length, he does not provide any general principles which govern their production. The author does, in this section, and it is here that he is most original. The principles of association laid down in this section are fundamental to the author’s “science of man,” to the extent that at the end of the Abstract, he refers to them as “to us . . . the cement of the universe.”

The Treatise

1. This section begins with an affirmation of a universal principle, which is a re-statement in completely general form of a claim made in the last section: “all simple ideas may be separated by the imagination, and may be united again in what form it pleases.” Given the truth of this principle, the actual operation of the imagination would be “unaccountable” if there were no “universal principles, which render it, in some measure, uniform with itself in all times and places.” If the ideas of the imagination were “entirely loose and unconnected,” their being joined together would be entirely a matter of chance. If this were the case, and there were no “bond of union among them, some associating quality, by which one idea naturally introduces another,” it would be “impossible” for there to be any regularity in the combination of simple ideas into complex ones. But in common life, there is great regularity in this combination. Any such basis of union is not to be regarded as an “inseparable connection,” since it was noted in the last section that the imagination is at liberty as to how it combines ideas, and it needs no unifying principles at all. For this reason, any principle of union must be regarded “as a gentle force, which commonly prevails.” It is the cause why languages correspond so closely to one another. Nature, as it were, shows us which simple ideas “are most proper to be united into a complex one.” There are three such “qualities, from which this association arises, and by which the mind is after this manner convey’d from one idea into another.” They are:

• Resemblance,
• Contiguity in time or place,
• Cause and effect.

2. That these three “qualities produce an association among ideas, and upon the appearance of one idea naturally introduce another,” is something that the author believes “will not be very necessary to prove.” In “the course of our thinking, and in the constant revolution of our ideas,” it is plain that the imagination makes an easy transition from a given idea to “any other that resembles it.” Thus, resemblance is a quality that by itself is a “sufficient bond and association” that guides the activity of the imagination. The quality of contiguity operates as the result of custom. The senses change their objects according to contiguity. [For example, as one views a scene from left to right, the order of the impressions is from one object to the adjoining object.] As this takes place again and again, “the imagination must by long custom acquire the same method of thinking, and run along the parts of space and time in conceiving its objects.” [We become accustomed to imagining objects whose parts are spatially contiguous. For example, the spatial unity of objects is preserved in most dreams.] The third quality, cause and effect, will be examined at length in Part 3, and therefore will not be treated further here, except to note that the relation of cause and effect among objects is responsible for the strongest connections in the imagination, which make one idea of objects readily bring to mind another.

3. We do not fully understand the strength of these associating qualities when we only consider how they connect ideas immediately. They also serve to connect ideas through intermediate ideas which bear the relation to the two ideas they relate to each other. We may impose many such intermediaries between two ideas, but each interpolation weakens the effect of the relation. [When B resembles A and C resembles B, often C resembles A to a much lesser degree than does B.] An example is a blood-relation, which is a relation of causation (“if I may be allow’d to use that term”). The relation between brothers, or between child and parent, is quite strong, while that between fourth cousins is much weakened. “In general we may observe, that all the relations of blood depend upon cause and effect, and are esteem’d near or remote, according to the number of connecting causes interpos’d betwixt the persons.”

4. The relation of causation is “the most extensive” of the three. [This may mean simply that causal relations are “most widely found,” as the annotations to the Norton and Norton edition put it. Or it might mean that causal relations can occur in more ways than the other two. The relations of resemblance and contiguity may only take place in one way, but the causal relation may hold in more than one way.] Thus, we may place two objects in the relation of cause and effect when one object is “the cause of any of the actions or motions of the other,” as well as when the cause is responsible for the existence of the effect. Surprisingly, the author justifies this claim of greater extensiveness by noting that we can explain easily why the imagination may connect objects in the cause and effect relation. It is because in the effect, the “motion or action” is in an object that continues to exist throughout the change, and indeed “is nothing but the object itself, considered in a certain light.”

5. The relation of cause and effect is not limited to the production of an action and motion in an object. We may call one object the cause of another when the former merely has the power to produce a motion or action in an object. This can be seen in the relations of interest and duty, “in which men influence each other in society, and are plac’d in the ties of government and subordination.” A master is one who “has a power of directing in certain particulars the action of another,” who is his servant, due to the master’s “situation, arising from force or agreement.” Similarly, a judge is a person with the power of disposing of the possession or property of any member of society, solely by rendering his opinion. [Thus, we call a master and a judge a “cause.”] A person has a power when he can convert the power to action merely by willing that it be so. The exertion of the will [apparently the referent of “that”] is considered possible in every case and probable in many cases. The exercises of the master’s will especially are considered as probable in cases where the obedience of the servant is “a pleasure and advantage” to the master.

6. The author has now concluded his presentation of the principles which unite simple ideas in the imagination“—principles that are needed because the imagination does not have to conform to the “inseparable” relation of the order of impressions, as does memory. “Here is 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.” The effects of these principles are “every where conspicuous,” but the causes of them are “mostly unknown, and must be resolv’d into original qualities of human nature, which I pretend not to explain.” The greatest duty of a “true philosopher” is restrict his inquiries into what can be established by “a sufficient number of experiments” and not be moved by “the intemperate desire of searching into causes,” which he sees “wou’d lead him into obscure and uncertain speculations.” It would be better in such cases to inquire into the effects, which are evident, than the causes, which are obscure.

7. The most remarkable effects of the principles of association are the complex ideas “which are the common subjects of our thoughts and reasoning, and generally arise from some principle of union among our simple ideas.” The complex ideas in question can be divided into the following:

• Relations
• Modes
• Substances

The Enquiry

Hume says in Section 3 that it is “evident” that ideas introduce one another with “a certain degree of method and regularity” in the memory and imagination. This is obvious in our systematic thinking, but it holds even in dreams and in the “loosest and freest conversations.” There is “a certain proof” that simple ideas are connected “by some universal principle” that affects all human. The argument is that even in languages that are isolated from one another, there is inter-translatability: even the most “compounded” words in these languages “nearly correspond” to one another.

No philosopher, apparently, has undertaken to “enumerate or class all the principles of association.” Hume finds the three discussed in the Treatise: resemblance, contiguity, and cause or effect. Similar examples are given. Although there may be other principles, if we carefully examine the cases we come across, we find the three at work, and the more cases that are resolved in this way, the greater the force of the claim that these are the only three principles.

There follows (in the editions before 1777) a description of “some of the effects of this connexion upon the passions and imagination.” The examples concern the unity of literary works in the realization of a plan by the author. Hume mentions the Roman poet Ovid as unifying his works according to the principle of resemblance, a historian according to both the principle of contiguity and that of cause and effect. In the latter case, the historian’s ability to make causal connections determines the perfection of his work. There follows a long discussion of the role of the principles in poetry. Hume concludes by noting that in literary works, passions most easily pass to individuals connected by his three principles, but then he breaks off the discussion by stating that it “would lead us into reasonings too profound and too copious for this enquiry. It is sufficient, at present, to have established this conclusion, that the three connecting principles of all ideas are the relations of Resemblance, Contiguity and Causation.”