§54. The Last Conclusion of Experimental Logic
Textbook accounts of the history of philosophy put Hume in a line of “British empiricism” with Locke and Berkeley, whose insidious principles he took to absurd conclusions, ending in a baffled skepticism he cheerfully accepted.
This interpretation began with Thomas Reid, a known antagonist, and James Beattie, one of the few men Hume disliked. It was confirmed by Dugald Stewart and J. S. Mill, who, according to Norman Kemp Smith, never read the Treatise of Human Nature or the Dialogues Concerning Natural Religion. Besides being a tendentious construction from inadequate sources by known antagonists, the textbook account slights Montaigne and Bayle, two of Hume's most important sources, and overlooks a line of admired and imitated moral philosophers, including Shaftesbury, Mandeville, Hutcheson, and Butler, none of whom were significant authors for Locke or Berkeley.In the Treatise of Human Nature, Hume presents himself as applying Newton’s experimental method to moral philosophy. He praises Newton as “cautious in admitting no principles but such as were founded on experiment; but resolute to adopt every such principle, however new or unusual.” Writing barely fifty years after Newton’s Principles, Hume seems to think of experiment as any deliberate consulting of experience. An experimenter looks and sees, even troubles to seek out for seeing, and does not answer from a book. These experiments arise from “a cautious observation of human life,” as it appears “in the common course of the world.” Of course experiments usually involve more than merely consulting experience; they provoke it, deliberately altering circumstances to induce controlled change. In practice, Hume understands that. Here is one of his experiments: “When we press one eye with a finger, we immediately perceive all the objects to become double.... By [this and] an infinite number of other experiments of the same kind...
we learn that our sensible perceptions are not possessed of any distinct or independent existence.”39A second quality of Newton’s science that appeals to Hume is his insouciance about experimental conclusions. Newton cannot explain the force of gravity, but he has the experiments, and all the evidence confirms that attraction operates as he describes, so gravity it is. If we cannot explain its force we must live with the mystery. Not a few of the beliefs we think we understand (stones fall) are actually mysterious and likely to remain so. Reason is only reasonable in the analysis of relations of ideas, when it deals with conventions created by reason in the first place, but extends no further, having no insight into connections in nature. If this is Newton, it is also nominalism: for all that reason understands, anything may produce anything else, and every cause is as inexplicable as the force of gravity. “We cannot give a satisfactory reason why we believe after a thousand experiments that a stone will fall or fire burn.” Therefore, “Nothing is more requisite for a true philosopher, than to restrain the intemperate desire of searching into causes, and having established any doctrine upon a sufficient number of experiments, rest contented with that, when he sees a farther examination would lead him into obscure and uncertain speculations.” Hypotheses nonfingo.40
Hume’s argument is not about causes, it is about inference and the role of reasoning in beliefs about causes. Impressions are the only data, reckoned to one of two sources, sensation or reflection. Our thought is driven beyond impressions by non-intellectual principles including sympathy and belief, which is not the mere vivacity of perceptions, as Hume initially explains it, being instead an attitude of the mind, a feeling, a sentiment carrying the mind on wings of passion, not logic, to the vivacious idea of a causally active world of bodies and selves. Belief is not an impression but a manner in which ideas are apprehended, a manner native to every impression, all impressions tending to confer their vivacity on any idea associated with them.
Experience acts on belief and also on feeling, which affects how belief’s content becomes operative. The content might be imaginary and completely unreasonable without changing the effect that it has on belief and action. Belief is not an act of understanding, nor is it something method might control. “Belief is more properly an act of the sensitive, than of the cogitative part of our natures.” From Shaftesbury, Hume learned something not to be found in Locke. “Nature will not be mocked. The prepossessions against her can never be lasting. Her decrees and instincts are powerful and her sentiments inbred.” Hume extends to science what Shaftesbury, Mandeville, Hutcheson, and Butler establish for morality, which is that values appeal to feeling, not reason. Nature and feeling, not logic and science, are the ultimate factors of mental life, with science no less than morality resting on “the particular fabric and constitution of the human species.”41
Hume suggested that his conception of human nature affords a new foundation for natural philosophy. “In pretending, therefore, to explain the principles of human nature, we in effect propose a compleat system of the sciences, built on a foundation almost entirely new, and the only one upon which they can stand with any security.” The expectation is soon dashed when Hume draws his conclusion that “reason is nothing but a wonderful and unintelligible instinct in our souls” announcing “no choice left but betwixt a false reason and none at all.” Yet even here, perhaps especially here, Hume is following his idea of Newton and taking a consistently experimental position in philosophy. “While Newton seemed to draw off the veil of some of the mysteries of nature, he shewed at the same time the imperfections of the mechanical philosophy; and thereby restored her ultimate secrets to that obscurity, in which they ever did and ever will remain”42
What Hume calls belief is not an alternative paradigm for natural philosophy, as medical judgment is for Locke.
Locke is skeptical of natural philosophy; the understanding is not up to it, not capable of certainty on the substances that operate in nature, but he allows a kind of judgment, modeled on medicine, that arises from the sagacious use of experiments. Hume also finds the science of nature closed to us, though in its place he puts not disciplined conjecture but impassioned belief. He does not want a new paradigm for natural philosophy. He wants the dichotomy of episteme and doxa, science and belief, which allows him to make his devastating point about feeling over reason. When the mind passes from one idea or impression to another—whether believing them to be cause or effect, same or different—it is imagination, not understanding, habit, not reason, feeling, not cognition that operates. Sentimental, passionate, egregious belief is all we have to think with, and it is enough. Hume adopts the usual usualism of the Pyrrhonist. Belief can be usual or unusual, but never sagacious and never scientia.43Ockham maintained, on theological grounds, that what can be thought separately without contradiction can exist separately by the absolute power of God. Inexplicably, the irreligious Hume makes the principle his own. What is logically distinguishable is really separable and actually separate, which makes the impossibility of demonstrating causality a foregone conclusion. “The contrary of every matter of fact is still possible, because it can never imply a contradiction and is conceived by the mind with the same facility and distinctness as if ever so conformable to reality” Ockham did not outright deny knowledge of causes; the knowledge would not be scientia, but would be prudent experimental cognition and not sheer vanity, a nominalist legacy Bacon and Locke developed. Hume dispenses with the legacy and the theology, only to find that experimental reasoning loses its rationality.
The last conclusion of experimental logic is that experiments are not logical. Hume makes explicit what was always in Ockham’s nominalism, the corollary of his absolute individuals. “The mind never perceives any real connection among distinct existences.”44