Notes on Hume's Treatise

by G. J. Mattey

PART III. OF KNOWLEDGE AND PROBABILITY

§ XIV. Of the idea of necessary connexion.

1. Since Section 2, Hume had been seeking an explanation for our idea of the philosophical relation between cause and effect. He had analyzed that idea in terms of contiguity, priority, and necessary connection. He then sought for an answer to this question: "What is our idea of necessity, when we say that two objects are necessarily connected together." Having failed at 1.3.2.12 to discover an impression that gives rise to the idea of a necessary connection, he undertook to investigate a different issue, why it is necessary that every beginning of existence have a cause. He professed the hope that this investigation would turn up something useful for the task of finding the impression giving rise to the idea of cause and effect. Having failed in Section 3 to discover the source of the belief in "the necessity of a cause" in pure reason, he sought it in experience. But rather than investigate directly how experience might give rise to this belief, he decided it best to "sink" this question into the question of how particular impressions (taken as causes) give rise to particular ideas of new beginnings (taken as effects of those causes). That task was completed in Section 13. So now the search again is for the impression that gives rise to the idea of a necessary connection. Such an impression is required by the Copy Principle enunciated in the first section of Part One.

So take two objects which are supposed to stand in the relation of cause and effect. They are always contiguous and successive, but no other relation hetween can be perceived. The view of the two objects can be enlarged to include other like objects in like relations of contiguity and succession. The enlargement seems to do nothing but repeat what has been found in the first instance, but in fact there is more. A new impression is produced by the process of repetition, and it is this impression that gives rise to the idea of necessary connection. This is an impression of the determination of the mind by custom to produce a like idea upon frequent repetition. "'Tis this impression, then, or determination, which affords me the idea of necessity." Hume has finally completed the search begun in Section 2 for the impression demanded by the Copy Principle.

2. Hume regards this conclusion to follow from the principles he has established. It might seem to the reader that it is unremarkable, and as such it would be easily forgotten. But the reader had better pay attention, since this conclusion bears on "one of the most sublime questions of philosophy, viz. that concerning the power and efficacy of causes." Because of the seriousness of the topic, Hume proposes to supply the reader with a fuller account of his doctrine and the arguments leading to it. He raises the hope that he will thereby make it more forceful and evident.

3. The issue of the "efficacy of causes" has been a matter of extensive disputes among both ancient and modern philosophers. Hume suggests that it would have been well of the disputants to have first examined the idea of the efficacy in question. "This is what I find principally wanting in their reasonings, and what I shall here endeavour to supply."

4. What is the idea of efficacy, agency, power, force, energy, necessity, connexion, and productive quality ("all nearly synonymous")? Philosophers have opted for "vulgar" or common definitions. But Hume's system requires that we begin by seeking the impressions which give rise to the ideas. If the idea is simple, then the impression will be simple, and if the idea is compound, then the impression will be as well. Hume will summarize in paragraph 14 the view that his own, "philosophical" account gives the correct application of the expressions in question, while the vulgar definitions are meaningless because they are applied wrongly. Paragraph 15 begins the positive, philosophical account of the use of these terms, while the next nine paragraphs are devoted to discrediting the meaningless adaptations of the vulgar conception given by the philosophers.

5. The most general and popular explanation, due to Locke, is to posit a power such as is capable of producing new productions in matter, in order to explain the changes in motion and variations in bodies that we experience. Here is a quotation from the chapter of Locke's Essay referred to in footnote 28.

The mind being every day informed, by the senses, of the alteration of those simple ideas it observes in things without; and taking notice how one comes to an end, and ceases to be, and another begins to exist which was not before; reflecting also on what passes within itself, and observing a constant change of its ideas, sometimes by the impression of outward objects on the senses, and sometimes by the determination of its own choice; and concluding from what it has so constantly observed to have been, that the like changes for the future be made in the same things, by like agents, and by the like ways,--considers in one thing the possibility of having any of its simple ideas changed, and in another the possibility of making that change; and so comes by that idea which we call power. (An Essay Concerning Human Understanding, Book II, Chapter XXI, "Of Power")

6. Since pure reason cannot justify the positing of a "power," the idea must come from particular instances of the "efficacy" which arise through sensation and reflection. Hume restates his Copy Principle, though substituting 'object' for 'impression.' Then an idea of efficacy must arise from an efficacious object, and moreover, an object in which the efficacy is "plainly discoverable to the mind, and its operations obvious to our consciousness or sensation." Otherwise, the idea is "impossible and imaginary." It might be thought that this dilemma can be avoided by the doctrine of innate ideas, but this "has been already refuted, and is now almost universally rejected in the learned world." So the task is now to find a "natural production" which reveals the operation and efficacy of a cause in a way that is clear and that cannot give rise to error.

7. We have all kinds of explanations: substantial forms, accidents or qualities, matter and form, form and accidents, virtues and faculties. The diversity of these opinions is "strong presumption" that they are all "without foundation." These principles are unintelligible and inexplicable: philosophers would not have had recourse to them if there were an intelligible substitute. The conclusion to be drawn from this is that no one instance can reveal efficacy, and that the philosophers are no better off than the vulgar in trying to produce it. Hume recognizes that this is a negative thesis, and so his only recourse is to challenge these philosophers to show him "an instance of a cause, where we discover the power or operating principle."

8. The failure of attempts to "fix this power" has led to the thesis that it is unknown. The Cartesians [here Hume has Malebranche and his followers in mind] claim that matter is inefficacious. If it could produce anything, it would be motion, but it cannot produce motion because its essence is extension, and extension implies only mobility, and not the power to move objects. [Note: Locke would call mobility a "passive power," but Hume is concerned only with what Locke called "active power."]

9. The impotence of matter led the Cartesians have recourse to the DEITY: it is God who is the "prime mover of the universe." God, on this thesis, created matter and gave it is "original impulse," continuing to sustain motion through the exercise of his power. This accounts for the motions, configurations, and qualities of matter.

10. But this thesis of divine power can be sustained only on the false presumption of innate ideas. On the true view, the Copy Principle, there must be an idea of a power in some instance of its exercise. We cannot produce such a thing. Since we have no impression of force, we cannot have an idea of a deity exercising force, which is an impious belief. To avoid this impiety, we should conclude that the idea of force which is thereby denied of the deity is an inadequate idea.

11. Some philosophers deny the Cartesian claim and attribute power to matter, which is a "second cause" (with God being the "first cause"). However, they admit that efficacy must lie in an unknown quality of matter. In that case, by the Copy Principle, there can be no idea of power or efficacy.

12. [A passage from the Appendix which Hume wanted to be inserted here.] The missing impression might be sought in a feeling we have of a power in our own mind when we exercise our will and produce thoughts and feelings. The resulting idea of power is then transferred to matter, as the motions of our bodies obey the will. The first objection to this claim is that it explains nothing, because it has "no more discoverable connection with its effects, than any material cause has with its proper effect." The reason is that we can distinguish between the exertion of the will and the production of an effect, and so whatever follows after the act of will might not have taken place. There is no way to fix the boundary between when the will is productive and when it is not. "We only perceive their constant conjunction; nor can we even reason beyond it." There is no internal impression of energy. In footnote 30 from the Appendix, we have Hume's defense of the piety of this conclusion. First, the existence of God can be inferred from the order of the universe, and secondly, the will of God is always accompanied by obedience, unlike the human mind, over which we have command "to a certain degree."

13. An idea of power in general would have to come from ideas of particular powers in an object, given the doctrine of abstract ideas discussed in Section 7 of Part One. But this leads us back to the problem of producing a clear case in which efficacy can be found in a single object. The problem is put differently here. From a single idea we cannot tell that it is impossible for anything but the effect to occur, since this would require demonstaration. This has already been rejected. Hume repeats his challenge from paragraph 7 that anyone objecting to the thesis produce the example. "But till I meet with such-a-one, which I despair of, I cannot forbear concluding, that since we can never distinctly conceive how any particular power can possibly reside in any particular object, we deceive ourselves in imagining we can form any such general idea."

14. There is no meaning to the vulgar definitions given by the philosophers. The mistake seems to arise from the misapplication of the true meaning of terms like "power" and "efficacy." So what is their true meaning? This will be answered in the subsequent sections.

15. The tie between two objects cannot be discovered from the simple consideration of one or both. So we do not derive the idea of power from a single instance. If all conjunctions of objects were entirely different from one another, we would never have an idea of cause and effect.

16. The problem with the other views is that they do not give proper place to "the multiplicity of resembling instances." This is really all that is needed to solve the problem. The idea of power cannot be something new discovered through repetition, due to the Copy Principle. So what repetition must do is to "either discover or produce something new, which is the source of that idea." We look to the "effects of the mutiplicity" which is an "enlargement" constituting the idea of power. Power can be understood as an effect of the multiplicity.

17. The first consideration here is repetition does not discover something new in the repeated objects. If it did, we could draw inferences from the first to the second, and it has been proved that we cannot. Or if we could, it wouldn't matter, because inference cannot produce a new idea.

18. The second consideration is that repetition does not produce something new. The two ideas are distinct and thereby separable. "They are entirely divided by time and place; and the one might have existed and communcated motion, tho' the other never had been in being."

19. So nothing new in the object is discovered or produced by resemblance, yet it is the source of the new idea. So what is the source?

20. Observation of repetition produces a new impression in the mind. "We immediately feel a determination of the mind to pass from one object to its usual attendant, and to conceive it in a stronger light upon account of that relation." This is the only effect of resemblance, so the idea of power is derived from it.

21. The foundation of our inference from cause and effect is the transition arising from the accustomed union. And necessary connection of cause and effect is the foundation of our inference. Therefore, the transition arising from the accustomed union is the necessary connection of cause and effect.

22. Since there is no impression of necessity that arises from the senses, it must arise from reflection. The only internal impression that is relevant is "that propensity, which custom produces, to pass from an object to the idea of its usual attendant. This therefore is the essence of necessity." Necessity exists in the mind, not in objects. The only alternative to the present view that necessity is a determination of thought is that we have no idea of necessity at all.

23. A comparison is made with the necessity lying in the act of the understanding comparing ideas ("which makes two times two equal four") and that uniting causes and effects. It is not placed in the causes, nor in God, nor in their concurrence, "but belongs entirely to the soul, which considers the union of two or more objects in all past instances. 'Tis here that the real power of cuases is plac'd, along with their connexion and necessity."

24. This is the most violent paradox in the treatise. Though the proof is straightforward and simple, it will be resisted. Hume summarizes the argument again. Although Hume enthusiastically endorses his own reasoning, he thinks that "with the generality of readers, the baiss of the mind will prevail."

25. Hume tries to explain this "bias" by noting that this is how we treat other qualities of objects, such as their sounds and smells. The mind "spreads itself" on the objects of the senses. It does the same thing with necessity.

26. Hume imagines that the solution given here will be thought extravagant and ridiculous. Were there no mind existent, there would be no causes. To make causes depend on thought reverses the order of nature. "To remove [the power] from all causes, and bestow it on a being, that is no ways related to the cause or effect, but by perceiving them, is a gross absurdity, and contrary to the most certain principles of human reason."

27. Hume makes an analogy with the protests of a blind man who is told that the color scarlet is distinct from the sound of a trumpet. We should not use the idea of power to signify something else which we do not know, but rather use it in a way that is intelligible and will not lead us astray. "This is the case, when we transfer the determination of the thought to external objects, and suppose any real intelligible connexion betwixt them; that being a quality, which can only belong to the mind the considers them."

28. At least contiguity and succession are independent of the mind, as is the fact that like objects are observed to have like relations in many instances. But the power of necessity cannot be similarly endowed on mind-independent reality. Hume's present reasoning can be converted into an instance of this "by a subtility, which it will not be difficult to comprehend." That is, he is applying the account of the mind-dependence of power to what goes on in the mind.

29. When we say that there is a necessary relation between external objects, all we really have is the determination of the mind to move from the object to the idea of another object. In the mind, we connect impressions and ideas, and say that the idea follows necessarily from the impression. But this can only mean that the mind begins with an idea of the impression and is determined to form an idea of the idea that resulted from the impression ("the idea of the one to that of the other"). "The uniting principle among our internal perceptions is as unintelligible as that among external objects, and is not known to us any other way than by experience." So just as there is no insight into "the internal structure or operating principle" of the external object, there is no insight into any principle operating in our minds.

30. Hume summarizes his position to this point and explains why he had to take such a devious route to get there. Ordinarily, we would begin by defining the relation of cause and effect and then examine how we make the inference from the one to the other. But because "the nature of the relation depends so much on that of the inference," Hume had to make the "seemingly preposterous" reversal in the order of consideration. Now that he has explained the inference from cause to effect, he can give a definition of the causal relation.

31. As was stated in 1.1.5, cause and effect can be viewed as a philosophical or natural relation. It is a philosophical relation when it is the result of comparing different ideas, and it is a natural relation when it is an associating of two ideas. He gives two definitions. "An object precedent and contiguous to another, and where all the objects resembling the former are plac'd in like relations of precedency and contiguity to those objects, that resemble the latter." Cause here is defined purely in terms of objects, but the account of causality was given in terms of ideas. So Hume proposes a second definition, which makes reference to the role of the mind in setting up the causal relation. "A CAUSE is an object precedent and contiguous to another, and so united with it, that the idea of the one determines the mind to form the idea of the other, and the impression of the one to form a more lively idea of the other." Hume thinks this is the best he can do. What he finds when he observes the way he generates a causal relation is that first there is in a single instance, one object precedes the other in time and is next to it in space, and then there is an enlargement of his view to other instances, where two objects share the same relation. This is due to the influence of constant conjunction which gives rise to custom. The relation of cause and effect "can never be an object of reasoning." Hume now takes his theory to be established.

32. Hume shows four corollaries to his definitions of a cause. 1) All causes are of the same kind. There is no distinction between the four kinds of causes enunciated by Aristotle: formal, efficient, material, final. The only cause is efficient [i.e., the agent that brings about the change.], "for as our idea of efficiency is deriv'd from the constant conjunction of two objects, wherever this is observ'd, the cause is efficient." There is no distinction between cause and occasion, as enunciated by Malebranche [i.e., God is the true cause of change, and the preceding object is only the occasion on which God exercises causal power]. According to the definition of cause, "if constant conjunction be imply'd in what we call occasion, 'tis a real cause. If not, 'tis no relation at all, and cannot give rise to any argument or reasoning."

33. 2) There is only one kind of necessity, not two (physical and moral). It is the same determination of the mind that gives the idea of a causal relation in both cases. Take away necessity and you have chance. Hume bases this claim on the fact that the mind is determined or not to pass from an object or another. There are degrees of determination of the mind, based on how strong the conjunction is, and so there are degrees of necessity. This holds even in the physical world, where there are different degrees of "constancy and force" in the conjunction and the determination of the mind. So such variation in human behavior does not indicate a different kind of necessity at work (i.e., "moral necessity").

34. There is also no distinction between power and its exercise.

3) It was shown earlier (Section 3) that there is no intuitive or demonstrative argument in favor of the "absolute" or "metaphysical" necessity of the principle that every beginning of existence has a cause. The denial of this kind of necessity to the principle is naturally repugnant to us, but it can be understood easily given the definitions of cause just given. If we define it in terms of constant conjunction, it is possible that there be no preceding and contiguous object which resembles the kind of object that has always preceded the beginning of existence. If we define it in terms of a determination of the mind, it is even more clear that there is no metaphysical necessity, since the determination of the mind is something that "is in itself perfectly extraordinary and incomprehensible. Moreover, we only know of it through experience and observation, so the "necessity" could not be shown by an intuitive or demonstrative argument.

36. 4) We have no reason to believe an object exists if we cannot form an idea of it. All reasoning concerning existence is causal, and causal reasoning requires ideas which are constantly conjoined. This is pointed out because it bears on the criticisms made in Part 4, Section 3, concering matter and substance.

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