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Hume's Pyrrhonian Skepticism and the Belief in Causal Laws
Graciela De Pierris
Hume endorses in no uncertain terms the normative use of causal reasoning. The most striking example of this commitment is Hume's argument in the Enquiry against the possibility of miracles. The argument sanctions, in particular, the use of scientific reflection on uniform experience issuing in causal laws of nature (E 114): "A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined." 1 These words should give us pause; for how can Hume so confidently say, after his skeptical conclusions concerning our causal beliefs, that "a firm and unalterable experience has established" the laws of nature, and that we can therefore produce "proofs" against miracles? The Treatise gives rise to the same puzzle. In this text, too, Hume confidently prescribes methodical reflection based on causal reasoning. For example, in Book One, Part Three, Section Fifteen, Hume offers eight "Rules by which to judge of causes and effects." These rules are more than descriptions of our natural causal inferences. They are meant to guide us in making better causal inferences; in Hume's words they "ought to regulate" our probable reasoning since (T 149): "by them we learn to distinguish the accidental circumstances from the efficacious causes." 2
Moreover, Hume consistently takes Newtonian science as a model for the proper employment of causal inferences in inquiries into matters of fact and, [End Page 351] in particular, as a model to be followed in his own science of human nature. 3 This paradigm of what the science of nature ought to be is understood by Hume as an inductive, experimental inquiry. 4 In the Enquiry, for example, Hume uses the label "sciences" for "politics, natural philosophy, physic, chemistry, &c." and in the preceding discussion argues that these sciences are not a priori but are based on causal reasoning (E 164-165). Thus, there are for Hume inquiries into matters of fact and existence that amount to more than blindly following natural propensities and habit. The sciences and many of our causal inferences in common life involve more than mere belief as a sentiment. They involve, in addition, careful reflection that results in improved causal inferences and thus provides normative standards. Yet, in thus upholding the normative use of causal reasoning in science and in everyday life, Hume appears to contradict his own radical skeptical conclusions concerning our knowledge of causation and induction. I here propose a novel way to resolve this puzzle.
To acknowledge the existence of a puzzle, however, amounts to accepting the now controversial view that Hume provides, and takes at face value, a radical skeptical argument concerning our knowledge of causation and induction. 5 Moreover, the attempt to resolve this puzzle involves rejecting the suggestion [End Page 352] that Hume, without awareness or concern, happily holds flatly inconsistent views. 6 It also goes against the more sophisticated suggestion that Hume lightly alternates among different psychological moods, or perhaps different perspectives, which might eventually issue in results that contradict each other but are sufficiently localized so as to prevent serious conflict. Such a view might lead us to conceive Hume's texts as an unstructured and arbitrary patchwork of reflections, driven by different psychological moods or by the embellishments of a radiant literary style. This kind of reading is unacceptable as an interpretative tool, however, as H. J. Paton has acutely noted in his criticism of the patchwork interpretation of Kant's Critique of Pure Reason. 7 For such a reading would place no constraints at all on the task of establishing which parts of Hume's text belong to which moods or perspectives. The suggestion that Hume offers an unstructured patchwork of reflections masks the novel and systematic distinction Hume draws between his radical philosophical...