What Impressions of Necessity?

What Impressions of Necessity? Antony Flew My question is this: "Why and how was it that Hume failed to find a kind ofimpression from which to legitimate the complementary ideas of physical necessity and physical impossibility?" We can best begin from his first published discussion of causation. 1. In Treatise 1.3.2, the section, "Ofprobability; and ofthe idea of cause and effect," Hume asserts that, "The idea ... of causation must be deriv'd from some relation among objects; and that relation we must now endeavour to discover."1 His first efforts are directed to establishing that two causally related objects must be both spatio-temporally contiguous and temporally successive, the cause object preceding the effect object. But "[h]aving thus discover'd or suppos'd" this conclusion, Hume finds that he is "stopt short, and can proceed no farther in considering any single instance of cause and effect" (T 76). We might, therefore, have expected that his next move wouldhavebeen to consider series ofresemblingcause objects and their relations to series ofresemblingeffect objects. But such a consideration is in fact deferred from section 2 until section 14, "Of the idea of necessary connection"; a section starting all of seventy-seven pages later. Instead, the immediately following paragraph reads: Shou'd any one leave this instance, and pretend to define a cause, by saying it is something productive of another, 'tis evident he wou'd say nothing. For what does he mean by production? Can he give any definition of it, that will not be the same with that of causation? Ifhe can; I desire it maybe produc'd. If he cannot; he here runs in a circle, and gives a synonimous term instead ofa definition. (T 77) The phrasing ofthat paragraph perhaps constitutes one of those infelicities in the Treatise which Hume was later to recognize and regret. For if and inasmuch as "causation" and "production" are synonyms, any adequate definition of either word must be equally adequate for both. Rashly assuming that his challenge toproduce such a definition will not and cannot be met, Hume proceeds at once to ask and to answer his own consequential question: Volume XVIII Number 2 169 ANTONY FLEW 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 consider'd as its cause. There isa necessaryCONNEXION to be taken into consideration; and that relation is of much greater importance, than any of the other two above-mention'd. (T 77) 2. But now, why "necessary connexion" rather than either "causal connexion" or "connexion" without prefix or suffix? Suppose that you were the Adam of the Abstract "created in the full vigour of understanding," yet altogether "without experience." (T 650). And suppose that you had noticed some A's both spatio-temporally contiguous to and precedent to B's. Then, assuming that your understanding was not only vigorous but also equipped with all the essential concepts, you might well ask yourself, or perhaps, if she was now available, your partner, whether there was any causal connection here at all; or, more specifically, whether these A's were causing these B's. You might even proceed to put the question to experimental test: either by producing further A's in hopes ofconsequentially producing furtherB's; or, whenA's occurredspontaneously, by trying to inhibit the subsequent occurrence ofB's. What such an Adam would surely not do—not unless he had developed proto-Humean desires: both to demonstrate the absence here ofany logically necessary connections; and thus, hopefully, also to discredit theidea that anyotherkind ofnecessity might beinvolved—is to suggest that the third, crucial, and so far unidentified element in any adequate account of causation must be necessary connection; as opposed, that is, to either causal connection or just plain unqualified connection. It is, of course, obvious that Hume himselfis eager to get on first to denying logically necessary connections, and then to the further business which he relates to this denial. For it is in the immediately followingsection 3, "Whyacauseisalwaysnecessary," thathe presents his argument for the conclusion that, whereas, "Every effectmust...