The Pursuit of Certainty. Shirley Robin Letwin

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СКАЧАТЬ he said, “an instance of an abstract idea which comprehends a still greater variety than that of space, and yet is represented in the fancy by some particular idea of a determinate quantity and quality.”³ The conception of space and time is exactly like the conception of relations, substances and universals. In all these cases, we are misled into turning the fixed names for relations into absolute entities. Such indefinite application of ideas which are originally relative to certain limited perceptions is characteristic of the human mind. It is the work of imagination, and is the result of custom.

      As Hume came to recognize in the course of the Treatise, the custom from which, he had said, abstract ideas arise must itself be dependent on a capacity to form general concepts and to make “distinctions of reason” between, for instance, figure and colour, motion and the body moved. It was a difficulty that haunted his whole enterprise—in order to explain how a general term comes to be applied, or how it comes to be, he had to allow that the mind could recognize the identity of an object through time and could apprehend a resemblance between particular images. Indeed, if a particular idea becomes general by being annexed to a general term, the recognition of a resemblance between particulars must occur before that use of the general term upon which the custom rests. How these operations were possible to a mind whose every idea is derived from an impression, Hume never explained. He merely took the relation of resemblance for granted as an ultimate fact of experience. Philosophers have since suggested that he might have escaped these difficulties by acknowledging and developing a supplementing and synthetic activity of the imagination at which he hints. But he could not have gone much further than he did without running a danger he was most anxious to avoid, of letting in by another door the kind of power he was trying to exclude.

      Custom played an even more remarkable role in Hume’s theory of causation. And far from denying the radicalism of his theory, he made certain his readers noticed that the notion of causality was at the heart of all discussions of human intelligence and that his views were most unorthodox:

      I doubt not but these consequences will at first sight be receiv’d without difficulty, as being evident deductions from principles, which we have already establish’d, and which we have often employ’d in our reasonings. This evidence … may seduce us unwarily into the conclusion, and make us imagine it contains nothing extraordinary, nor worthy of our curiosity … for which reason I think it proper to give warning, that I have just now examin’d one of the most sublime questions in philosophy, viz., that concerning the power and efficacy of causes, or that quality which makes them be followed by their effects. ”¹

      Hume had no wish to deny that there was a real connection between cause and effect or that all our reasoning depended on our being convinced that the connection was a necessary one. Quite the contrary, the very necessity of the causal relation was crucial for his purpose. That cause and effect were connected by contiguity and succession, Hume granted at once. But that did not explain, he pointed out, what was really distinctive about the causal relation, that it seemed to be a necessary connection: “Shall we then rest contented with these two relations of contiguity and succession as affording a compleat idea of causation? By no means. An object may be contiguous and prior to another without being considered its cause. There is also a necessary connexion to be taken into consideration.”² We can see that the dog moves and that the stone does not; we see the facts and can conceive of their contrary; yet we say that the dog must move and the stone can not. In the same way, we do not say simply that every change has a cause, but that it must have a cause. What gives us assurance of that necessity?

      If the traditional answer that the necessity is seen by reason, by an intuitive insight into the nature of the cause or of the effect were correct, Hume argued, we should be able to see causal necessity from one instance. We could then say that it was impossible for the one object not to follow, or be conceived not to follow. But in fact, we can conceive of causes and their effects as unconnected, and what is even more important, we never conclude that there is a causal connection until we have seen the same events related in the same way a number of times. As there is nothing in several instances repeated that there is not in any one of them, it cannot be that anything within the objects gives rise to the idea of necessity.¹ The cause must then lie in the mind, not in the objects:

      Tho’ the several resembling instances which give rise to the idea of power have no influence on each other, and can never produce any new quality in the object … yet the observation of this resemblance produces a new impression in the mind, which is its real model. … Necessity, then, is the effect of this observation, and is nothing but an internal impression of the mind, or a determination to carry our thoughts from one object to another.²

      The necessity assumed is not, and cannot be, a necessity of reason (i.e., intuitively or demonstratively understood); it is only a necessity of feeling, in short, a belief, and it arises from custom.

      Hume thus reduced what had formerly been described as an intuition about the essence of things to nothing more exalted than an experience of a customary conjunction between two objects. Again, he was involved in the difficulty that afflicted his analysis of abstract ideas. He did not explain what enabled the mind to recognize “like” causes, or customary conjunctions. If, in fact, we can know only what we have already experienced, how can we depart from experience to recognize an object’s similarity to the one we have experienced in the past? But Hume’s attention was concentrated on what he was denying, that the causal inference was an operation of reason enabling man to discover the rational pattern imprinted on nature by the Divine Mind. Having shown that merely custom explained the feeling of necessary connection between cause and effect, Hume left “those who delight in the discovery and contemplation of ‘final causes,’ “ to “employ their wonder and admiration” elsewhere.¹ He had also eliminated the supposed difference between “moral” and “physical” necessity, for he had shown that all necessity lay in the mind, and arose from the influence of the repeated, constant conjunction of two objects. Instead of necessity there was only chance, reduced to order by custom.²

      He had demonstrated, Hume felt, that reasoning never gives rise to “a new original, simple idea,”³ that nowhere in man is there anything “like this creative power, by which it raises from nothing a new idea, and with a kind of Fiat, imitates the omnipotence of its Maker. ”.”⁴ It seemed that human thought possessed unbounded liberty and power, but closer examination revealed that it is “confined within very narrow limits,”

      and that all this creative power of the mind amounts to no more than the faculty of compounding, transposing, augmenting, or diminishing the materials afforded us by the senses and experience. … In short, all the materials of thinking are derived either from an outward or inward sentiment; the mixture and composition of these belongs alone to the mind and will.⁵

      The implications for the activity of philosophizing were not comfortable. By reducing reason to a combination of imagination and sense impressions, Hume had made it impossible to say why what we believe is true, or in any way to establish the certain validity of our beliefs. He had described the workings of the mind, but in doing so had merged logic with psychology; his description of the causal relationship had made it impossible to explain it. Most awkward of all, his method had not accounted for his own philosophizing. The picture he had drawn of the limitations of human knowledge ruled out his own ability to construct it. He had in fact disproved his tide to prove or disprove anything. His Treatise could only be a miracle, unrelated to the rest.

      It had not, however, been an interest in discovering the nature of knowing, for its own sake, that had driven him into philosophy. The point of his argument was moral, rather than epistemological, and this he made perfectly plain by concluding his analysis of human understanding with a section on the reason of animals.

      Having demonstrated how the human operation that had hitherto been traced to a spiritual power, reason, was no such thing, he then turned the question round. СКАЧАТЬ