Jane O’Grady explores the beautiful, paradoxical philosophy of David Hume
By Jane O’ Grady (reddit.com)
Portrait of David Hume (1711-1776), 1766
David Hume, a master of paradox and wit, is often said to be the greatest English-speaking philosopher who has ever lived. He was a figure of the eighteenth-century Scottish Enlightenment, and yet, like the Romantics, he deflated the status of reason, and elevated that of emotion, the natural, and human animality. Once regarded as the great arch-sceptic, he is now considered to be a naturalist, incorporating humans into empirical enquiry, as part of, rather than transcending, nature. He treated the human mind as a scientific specimen to be explained, and his diagnosis – that we are driven by unconscious mental mechanisms, habit and emotion – influenced Darwin, Freud and cognitive science, Bentham’s Utilitarianism, Logical Positivism and the philosophy of science.
Hume was born in 1711 near the English–Scottish border. According to Lord Charlemont who met him in middle age, no one looked less like their real character – Hume’s obesity conveying more “the idea of a turtle-eating alderman than a refined philosopher”. But he had been skinny and “raw-boned” (his own description) when, after leaving Edinburgh University without a degree, he “found a certain boldness of temper [which led him] to seek out some new medium, by which truth might be established”. In pursuing this for the next three years, he was “infinitely happy”, until, at the age of eighteen, an unknown, almost-symptomless malaise (probably depression) deflected him from study. After one of his several intermittent spells of unsatisfactory employment (he was, respectively, a merchant’s clerk, librarian, tutor to a mad marquis, secretary to a general and to an ambassador), he went to France in 1734. While staying at Descartes’s old college La Flèche, and amicably quarrelling with the Jesuits, he wrote the Treatise of Human Nature. The first part of it was anonymously published in 1738, when he was twenty-seven, the second in 1740, and, as a whole, it “fell deadborn from the press, without even reaching such distinction as to excite a murmur among the zealots”. There is much dispute over whether Hume’s Enquiry Concerning Human Understanding (1748) and Enquiry Concerning the Principles of Morals (1751) were intended to re-formulate or replace the Treatise. He twice applied for philosophy professorships, and was each time rejected, mostly on the grounds of his (denied) atheism; and he was chiefly renowned for his essays (several of which critiqued religion), his histories of England and his wit. Much loved and feted in Edinburgh, London and Paris, he died (probably of bowel cancer) in 1776. Adam Smith, one of his many illustrious friends, declared him “approaching as nearly to the idea of a perfectly wise and virtuous man as perhaps the nature of human frailty will permit”.
About a hundred years later, a partial translation of the Treatise woke Kant from his (self-described) “dogmatic slumbers” – he realized that, according to Hume’s intricate dissection of human thinking, metaphysics was impossible. Descartes had claimed that the mind is what we know best, and that it is free – exempt from the causation that governs the material world. Hume wrote that “the essence of mind is equally unknown to us with that of external bodies”. Extending Descartes’s “mechanical philosophy” into the mind, he set out to discover the mental equivalent of Newton’s laws of physics. Descartes, Locke and other seventeenth- and eighteenth-century philosophers (impressed by the discovery that sound, rather than being “out there”, is in fact the result of vibrations interacting with our ear drums and auditory nerves) held that what we actually perceive are not things around us but the “ideas” that either accurately copy, or somehow systematically represent, those things; our knowledge, therefore, consisting of the combination of “ideas”.
Hume disliked the way “idea” lumped together raw, instantaneous sensory experience with concepts and memories. He used the term “impressions” for the immediate elements of sensibility – our perceptions of colour, taste, shape, for instance, and of emotion and desire – in contradistinction to the “ideas” which (he said) are fainter but more lasting copies of these impressions, and which, in turn, “return upon the soul” to produce new impressions. Having received an impression of pain from touching a thistle, for instance, you form and store a less vivid idea of the pain, and that idea is reawakened into an impression of aversion whenever you come within touching range of a thistle.
“Impression” suggests the metaphor of an imprint on malleable wax by something outside it, but Hume was more consistent than other empiricists who claimed that our ideas are all we perceive, while simultaneously claiming that those ideas resemble, or fail to resemble, the things we can’t perceive. He was non-committal as to what, if anything, causes impressions. Instead he concentrated on working out what the mental mechanisms must be by which (the way he envisaged it) little units of experience and thought are pinged into different channels and combinations.
Hume postulated three “principles” (a notion of resemblance, of “contiguity” and of the cause and effect of present impressions) which move the mind from one impression or idea to some other idea – although not ineluctably, merely by “a gentle force”. We can, of course, combine, augment and modify our ideas as we please in imagination, but we cannot choose whether or not to believe these imagined notions: our beliefs cannot be “commanded at pleasure”. Depending, instead, on the forcefulness with which ideas strike us, our beliefs are more visceral than rational. And, in order to qualify as genuinely constituting knowledge, a combination of ideas has to be ultimately traceable back to the impressions from which it was first copied (which could, as with Julius Caesar’s recorded account of crossing the Rubicon, be someone else’s impressions). Apart from verbal definitions and logical “relations of ideas” (which, if true, are non-contradictable), “facts” that are not based on original impressions are not facts at all; books containing them, Hume wrote, should be thrown on the fire.
The corollary of Hume’s system is that, because we lack the impressions that are required to be the initial foundations to our ideas, our most fundamental beliefs are baseless. We have impressions (and subsequent ideas) of colours, shapes, etc, but lack any impression of their continuous and self-standing existence when not perceived – so why are we so confident that there is a world beyond our experience? Similarly, when we introspect, we encounter numerous fluctuating impressions (“of heat or cold, light or shade, love or hatred, pain or pleasure”), but an impression of self eludes us; therefore our idea of it is invalid. “Ourself, independent of the perception of every other object, is in reality nothing”, just “a bundle of perceptions”, or something like “a republic or commonwealth”, the citizens of which are only nominally united. Again, we see one type of thing or event constantly preceding another type of thing or event, and say the first causes the second, but however many times we experience that sequence of things or events, nothing new is added to our initial experience of it. The first time we witness a conjunction of events/objects is no different from the next and the next; each is just a repetition of the same kind of impressions we’ve already had; and, if one instance of cause and effect doesn’t show us necessity, then many such instances won’t either. We have no impression of what makes the second follow from the first; yet, without an impression of the necessity that connects them, we have no basis for believing in causation. In any case, just because up until now bread has always nourished us, or we have incessantly seen medium-sized things fall when let go of in mid-air, what reason do we have to assume that these hitherto “constant conjunctions” will go on happening? To argue that the future will be like the past because it always has been is “taking that for granted, which is the very point in question” – why should it be? There is “no known connexion between [a loaf’s] sensible qualities and [its] secret powers”, for instance. Why assume that, because certain sensible qualities are now, and have always been, attended with the power to nourish, they always will be? “Your appeal to past experience decides nothing in the present case”, said Hume.
It is no help in escaping Hume’s iconoclasm to say that we now know far more than eighteenth-century scientists about, for instance, bread’s then-“secret powers” – that it contains carbohydrates, and that the hydrogen and oxygen in the carbohydrates decompose to release energy. Hume is surely right that any such knowledge “only staves off our ignorance a little longer”. However far down we go in studying nutrition or anything else, the connection between disparate things and events remains unnecessary and unknown, which means that ultimate explanation eludes us. Induction – inferring from repeatedly observing similar particular instances of an object or event to general laws about it – is the very lynchpin of scientific enquiry, but thanks to Hume, it has become a problem, and none of the claims to solve it is successful.
If the external world is so dubious, where is everything? “Where am I, or what?” cried Hume in the Treatise. He was more rigorously sceptical than the original Sceptics – unlike theirs, his degree of scepticism, and of scepticism about his scepticism, fluctuated according to mood, food and weather, he said, and couldn’t be continuously sustained. Not just because, whenever feeling himself “inviron’d with the deepest darkness”, in “philosophical melancholy and delirium”, he would go out, dine, play backgammon, and be “merry with [his] friends”; but because he always found himself forced to “yield to the current of nature, in submitting to my senses and understanding”.
Although, as a philosopher, he doubted causation, induction, the external world, the self, “as an agent, I am quite satisfied” about them, he said. Like a boat that glides forwards due to momentum, our mental mechanism, without our awareness or volition, seamlessly bridges the gaps in our (in fact discrete) perceptions, so that there seems to be a continuous world of things existing independently of our perceiving them.
Each observation of “constant conjunctions” – that is, pairings of things/events that stand in an apparent causal relation – is, strictly speaking, the same. Yet something does change – after we have witnessed a few examples, we come to believe that the second half of the pairing necessarily follows from the first: when we see one billiard ball shooting straight towards another, we come to feel that the second must move on impact. We infer that the ball will roll away, not from reasoning but because our “natural instincts” – our imagination, twinned with custom or habit – “determine” us “unavoidably” to draw that inference. “The necessary connexion depends on the inference, instead of the inference’s depending on the necessary connexion.” As for continuity of the self, Hume, with the liberality of a great philosopher, admits that he is baffled by it, but “’Tis evident, that the idea or rather impression of ourselves is always intimately present with us”, and is clearly the “object” to which both pride and humility are directed. At any rate, it is not (à la Descartes) up to us to “assert” or not assert the truth of the ideas we have. The units of experience are involuntarily moved by forces that we have no access to.
Heralding modernity, Hume argues that reason is not our essence – that, as Arthur Schopenhauer would say, “we are not winged cherubs without a body” but rooted in the natural world. Where Descartes says that any beliefs without rational justification should be rejected, Hume argues that just because we have no rational grounds for many of our beliefs, it does not mean that we have no reason to hold them. Our beliefs are species-specific, not non-perspectival and absolute. Descartes’s project for a purely objective conception of the world is impossible. Indeed how fortunate that we rely on non-rational instincts that work “infallibly”, unlike the “fallacious” (in practice) deductions of reason.
But isn’t Hume being rather devious? Even as he speaks of things (the external world, self, necessary connection) seeming a certain way to us, he concurrently says that they don’t in fact (perceptually) seem that way. If our “impressions” are the ultimate units of experience, then surely the first sort of “seem” is illegitimate. He speaks at times of reason as an inferential instinct, a sort of “mechanical power” that we have in common with “the beasts”, but elsewhere he speaks of it as if it were a nature-transcending periscope, at odds with our survival instinct, and luckily thwarted by it. And while claiming that we have no impression of a “necessary connexion”, and therefore nothing on which to base a valid idea of it, he relies on causation to explain how it is that we come to have the (unjustified) sense of necessary connection (and of much else as well).
Is there, then – even though it is impossible for us to gain reliable empirical evidence for it – an external world? Does it contain our minds, and thus the “principles of connexion” which cause us – even though we never experience them as such – to believe in the existence of causal necessity, a material world and our selves? How, anyway, is Hume entitled to pontificate about the impressions and ideas, and their “principles of connexion”, in his own mind or anyone else’s except by reasoning about how they must operate? He talks as if mental units are propelled towards one another like tiny balls in a game of bagatelle, as if he can observe them from the outside, as it were. Whereas surely, when they are his, he only observes their content – what they are of (colours, smells, constant conjunctions). He has to infer how they function, and that other people’s impressions and ideas work similarly to his own. In neither case can he observe the little units that (in his metaphor) act as containers of experiential content, or the operations that propel them.
Hume dances daintily between paradoxes, extracting truth from between the teeth of contradictions. He does the same in his moral philosophy. Any moral system he’d encountered, he said, makes it seem that moral prescriptions are to be deduced from factual observations – that we derive “ought” from “is”. But this is to ignore that to rise from “is” into “ought” requires a take-off from a descriptive type of discourse and behaviour to speaking and acting in a quite different dimension. The “therefore” in “She is starving therefore I should feed her” is not a logical one. And where, Hume wondered, when we witness an act of “wilful murder” or of generosity, do we find an impression of the respective wickedness or virtue in either act? As with necessary connection, the impression we are looking for is not an “external” impression (an observable part of an act of generosity or of wilful murder) but an “internal impression” – a visceral feeling of approval or disapproval which results from observing such actions. Why? Because for all of us the desire for happiness, and aversion to suffering, are our ultimate motivations; and, unlike Bentham (whose Utilitarianism Hume inspired), Hume provides a mental mechanism (“sympathy”) that shifts us from self-interest to concern for others. He is not begging the question by using an already-moral term to explain morality naturalistically. “Sympathy” in his terminology is a pre-moral faculty for sensing viscerally, as well as deductively, the feelings of others as these are demonstrated in their behaviour, so that as with a violin’s vibrations transmitted from one string to another, observing (the evidence of) other people’s emotions plucks at our own. We naturally tend to be discomfited by seeing someone else’s suffering (unless he is our enemy) and prefer vicariously to enjoy his ease and pleasure. This automatic sensitivity to others’ feelings is our impetus to morality; and is not just an individually subjective feeling but more-or-less universal among the human species. It may not be rational, but, said Hume, “reason is inert”; by itself it can’t persuade us to move from is to ought. “Reason is, and ought only to be, the slave of the passions.”
Hume does enlist reason to smooth out the partiality and localization to which sympathy is prone, and, like Adam Smith, he invokes an impartial observer. Not entirely consonantly with the rest of his emotion-based morality, he also claims that we perceive moral values analogously to how we indirectly perceive sounds, tastes, colours, etc; not because they are as such in the fabric of the world but because our own human nature makes us apprehend certain features of reality in a certain way. No one denies the existence of moral distinctions, Hume said, except out of affectation, and the attempt to appear clever. Who could genuinely think all characters and actions to be equally likeable and commendable? Everyone “must often be touched with the images of Right and Wrong”.
What Hume says in his epistemology is equally applicable to his moral philosophy. “When we see that we have arrived at the utmost extent of human reason, we sit down contented; tho’ we be perfectly satisfied in the main of our ignorance, and perceive that we can give no reason for our most general and refined principles, beside our experience of their reality.” Belief has to be “founded on something natural and easy”; it tends not to be whole-hearted when “the posture of the mind is uneasy” or “forc’d and unnatural”. Strained philosophical reasoning may give us a view that is accurate but also – as in the clear-sighted bleakness of depression – diseased and abnormal. Our inadvertent, comfortable commonsensical beliefs are probably wrong, but, despite reason, we are compelled to hold them. We unwarrantedly believe that things are (mostly) real, connected and all right, and this normal maladjusted vision is healthy, and conducive to our own, and the species’, survival.
Clearly Hume himself often distorts his mind into uncomfortable positions, which is how he produces his beautifully convoluted and paradoxical philosophy. Hume reveals wheels within wheels, and where the wheels are is uncertain. But, as he said, “an object can exist, and yet be no where: and I assert, that this is not only possible, but that the greatest part of beings do and must exist after this manner”.
Jane O’Grady taught philosophy of psychology at City University, co-founded the London School of Philosophy and writes obituaries for the Guardian. Her book on Enlightenment philosophy will be published in January