Note: this is excised rough material from the draft of a book that will be in the works for likely many years. It is a bit choppy and derived partially from teaching material. Notes have not been formatted. It has been posted here as I often pick on Hume on social media, but haven’t the room to explain why in the length of a tweet–or the motivation.
An epistemological shriveling
The end result of David Hume’s skeptical empiricism is a radical diminishing of knowledge. It is in Hume we find not only the clearest formulation of the pseudo-problem of the external world, but also a more fully explicated thesis of usefulness as the sole criterion of value. Though he was not known as a utilitarian, it is quite easy to see how he fertilized the soil for an explicit doctrine of utilitarianism.
The atomistic theory of Locke–that knowledge is built up by an accretion and subsequent relating of sensory experiences–makes its way unimpeded into Hume’s epistemology. His treatment in the shorter, more concise, and more mature Enquiry Concerning Human Understanding (as opposed to the longer, rambling, and less-refined Treatise on Human Nature) stands upon the presupposition, explained only in the Enquiry’s final section, that our perceptions alone are present to our minds, and certitude of the external world causing those perceptions an impossibility:
By what argument can it be proved, that the perceptions of the mind must be caused by external objects, entirely different from them, though resembling them (if that be possible) and could not arise either from the energy of the mind itself, or from the suggestion of some invisible and unknown spirit, or from some other cause still more unknown to us? It is acknowledged that, in fact, many of these perceptions arise not from anything external, as in dreams, madness, and other diseases. And nothing can be more inexplicable than the manner, in which body should so operate upon mind as ever to convey an image of itself to a substance, supposed of so different, and even contrary a nature.
It is a question of fact, whether the perceptions of the senses be produced by external objects, resembling them: How shall this question be determined? By experience surely; as all other questions of a like nature. But here experience is, and must be entirely silent. The mind has never anything present to it but the perceptions, and cannot possibly reach any experience of their connexion with objects. The supposition of such a connexion is, therefore, without any foundation in reasoning.
The guiding presupposition of modern philosophy—that the “mind has never anything present to it but the perceptions”—finds its chief support in human disagreement: you and I, seeing the same thing, and interpreting it differently, consider it differently. Therefore, the moderns conclude, what we each know is not the same thing, but only our own impressions of that object; which puts the whole of reality existing independently of our own minds into doubt.
It comes as little surprise, then, that Hume’s Enquiry, after having discussed the different kinds of philosophy, begins with an egregious case of viciously circular argumentation. He seeks to explain how we arrive at our ideas, as the units of our abstract knowledge. Ideas, he says, along with impressions exhaustively form the category of our perceptions. While human imagination seems limitless, and therefore we are unlimited in our ideation, “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.” Because he follows Locke in the belief that we first possess only simple perceptions—that is, perceptions indivisible in meaning or content—and later form complex perceptions out of these simples, he has already all but closed the window for a transcendental ideation. It does not take him long to close and seal it completely:
All ideas, especially abstract ones, are naturally faint and obscure: The mind has but a slender hold of them: They are apt to be confounded with other resembling ideas; and when we have often employed any term, though without a distinct meaning, we are apt to imagine it has a determinate idea annexed to it. On the contrary, all impressions, that is, all sensations, either outward or inward, are strong and vivid: The limits between them are more exactly determined: Nor is it easy to fall into any error or mistake with regard to them. When we entertain, therefore, any suspicion that a philosophical term is employed without any meaning or idea (as is but too frequent), we need but enquire, from what impression is that supposed idea derived? And if it be impossible to assign any, this will serve to confirm our suspicion.
Ironically, Hume states as his goal in the Enquiry the rendering of philosophy intelligible and useful. Here, however, so long as he is followed, not only is philosophy rendered unintelligible and useless, but a coherent view of any two things whatsoever is forever lost. In this section of the Enquiry, Hume attempts determination of how we attain knowledge. He claims that ideas are nothing but weaker reflections or copies of our impressions and then denies validity to any idea which cannot be shown to derive from an impression. Where then did that idea come from, if every idea is nothing but a copy of an impression? To claim that all our knowledge derives from impressions, and that ideas irreducible to impressions are not valid, or real, cuts our minds off from the thread whereby the web of our world-contextualized lives: namely, relation; for relation, it cannot help but be noted, is an idea of which there is no sensory impression.
While we would have to say that the ultramodernist perspective of today hews much closer to Hume’s skepticism than Descartes’, the practical result of either is the same: “knowledge” becomes confined to a realm of mathematicised abstraction, and everything else is simply a matter of “experience”, incapable of veridical assertion except as a report of subjective interpretation—in other words, the only truths of experience are truths only for those who experience them. While we may discuss and share the events of our personal lives, their meaning is relative entirely to the individual, matters of mere opinion incapable of being or resulting in definitive and true knowledge.
You can find this attitude of cognitive division reflected today not only in prominent intellectuals, but also in the structure of institutions of higher education: divided into schools and departments, without any unifying intellectual goals. The natural sciences stand apart from the liberal arts (or humanities), which are distinguished (hopefully) from the social sciences, which likewise stand apart from the school of business. Although there are increasing numbers of interdisciplinary curricula, programs, and classes, this increase is a reactionary response to recognition in the world of business that students with well-rounded educations make better employees. Little if any meaningful guidance is given to the integration of diverse disciplines; rather, it is noted that a well-rounded education which enables students to incorporate material from their disparate courses results in more creative, cross-collaborative solutions; and, moreover, employees with richer, fuller, more healthy personal lives—a health promoted by education in the humanities—are happier, and therefore more productive. The problem-solving mentality characteristic of modern philosophy keeps divided the nature of cognition and keeps the realm of self-transcending truth or knowledge restricted to the discoveries of the physico-mathematical model of inquiry.
A divorce of fact and value
It is a direct consequence of this division of cognition that values, i.e., intelligible units of worth derived from the evaluation of an object, are divided from facts, i.e., intelligibly measurable units of symbolic precision concerning what is known about some object. For the physico-mathematical model only ever unveils facts, and never values, either aesthetic or moral. Such a scepticism about their apprehension has led to a scepticism about their existence; not, that is, that there do not exist any values whatsoever, but rather that these values are purely and always subjective in their nature.
Hume rather famously put this in terms of the difference between “is” statements, which describe a fact, and “ought” statements, which indicate a projection of value into the external world:
In every system of morality, which I have hitherto met with, I have always remarked, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surprised to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is, however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, ‘tis necessary that it should be observed and explained; and at the same time that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it.
In other words, there is no statement of “ought” which can be deduced from any statement of “is”: were I to say that heterosexuality is natural, that implies in no way that homosexuality ought to be condemned, corrected, or altered; were I to say that monogamy is better than polyamory, the implied ought—that one should have a single spouse and no other such intimates—reflects nothing more than a preference of my own heart.
This placing of value in a unique and universalized subjective point of view seemingly undermines all convention. We hold animals blameless for incest, Hume notes, but condemn humans because they have a “reason” which may discover an initial moral problem—which initial moral problem, he asserts, cannot actually be found. Why then, do we condemn it? Why, for that matter, do we condemn anything?
Take any action allowed to be vicious: Willful murder, for instance. Examine it in all lights, and see if you can find that matter of fact, or real existence, which you call vice. In which-ever way you take it, you find only certain passions, motives, volitions and thoughts. There is no other matter of fact in the case. The vice entirely escapes you, as long as you consider the object. You never can find it, till you turn your reflexion into your own breast, and find a sentiment of disapprobation, which arises in you, towards this action. Here is a matter of fact; but ‘tis the object of feeling, not of reason. It lies in yourself, not in the object. So that when you pronounce any action or character to be vicious, you mean nothing, but that from the constitution of your nature you have a feeling or sentiment of blame from the contemplation of it.
While today, we are furnished with better biological knowledge than Hume, and so to the question of incest is added the consideration of biological deformity rendered through too-similar a genetic pattern. Genetic diversity allows for the continued thriving of a species. However, we possess not only better biological knowledge than existed in Hume’s time, but also better biological control. That is, given contraceptive methods which, used in the correct manner, are effective in nearly every use, and given access to abortion, through which a perverse genetic inheritance can be terminated prior to any extensive development, the question must be raised anew: why is incest wrong? Why do we disapprove of the action? Is there anything in the act itself to which we can point? The same, Hume says, is true of murder. Most people would be more inclined from the basic societal standpoint to disagree with Hume, because we are taught from a very early age that hurting others is wrong. But why is it wrong in and of itself? Is there some molecule released in the act of murdering which makes it wrong, or bad? Is there some good in the person which is torn apart by the happening of being murdered? For the most part, the only foundational reason most human beings can readily identify, as to why murder is wrong, is that we ourselves do not want to be hurt, or those we love, or for our society to be undermined in such a way that our happiness is imperiled. Now, this line of thinking gets us ahead of ourselves, into contractarian thinking—and it shows us, perhaps, part of why contractarian thoughts evolved as they did—but the essential question Hume asks, is one we have to ask ourselves: where do we discover right and wrong, good and bad? Is it merely, nothing more, than a sentiment, a feeling? If so… can we ever say that something is right or wrong, or only that we do not like it?
Following Hume in his separation of fact and value, and the relegation of moral judgment to expressions of sentiment, was not intensely popular in his own time; but by the third-way point of the twentieth century, logical positivism had adopted the Humean position wholeheartedly. Thus when A.J. Ayer asked “whether statements of ethical value can be translated into statements of empirical fact,” his answer, no surprise, was that “we have seen that sentences which simply express moral judgements do not say anything. They are pure expressions of feeling and as such do not come under the category of truth and falsehood.” J.L. Mackie’s second-order moral scepticism paints the same picture, to which he adds the consideration that the externalization of our feelings results in the setting-up of these feelings as an external moral authority. The denial of such authority, Mackie says, itself produces a powerful emotional response:
The denial of objective values can carry with it an extreme emotional reaction, a feeling that nothing matters at all, that life has lost its purpose. Of course this does not follow; the lack of objective values is not a good reason for abandoning subjective concern or for ceasing to want anything. But the abandonment of a belief in objective values can cause, at least temporarily, a decay of subjective concern and sense of purpose. That it does so is evidence that the people in whom this reaction occurs have been tending to objectify their concerns and purposes, have been giving them a fictitious external authority. A claim to objectivity has been so strongly associated with their subjective concerns and purposes that the collapse of the former seems to undermine the latter as well.
That is, Mackie, prior to presenting his arguments as to why moral values are subjective, argues that those incensed by this notion are themselves expressing a subjective value: namely, despair at the thought that their values are not authoritative. Entailed in this claim is that external authority is not necessary for valid meaning.
Mackie then gives two claims for why morality is subjective. The weaker of these two is that from relativity: that is, it is evident from history, sociology, and anthropology, that given the same facts of life, different individuals and groups have radically different moral judgments. This is not a proof of subjectivism, but evidence considered in support of it. The second, and stronger argument, is what he calls the argument from queerness:
This has two parts, one metaphysical, the other epistemological. If there were objective values, then they would be entities or qualities or relations of a very strange sort, utterly different from anything in the universe. Correspondingly, if we were aware of them, it would have to be by some very special faculty of moral perception or intuition, utterly different from our ordinary ways of knowing everything else.
The empirical presuppositions here are obvious; as Mackie adds, “none of our ordinary accounts of sensory perception or introspection or the framing and confirming of explanatory hypotheses or inference or logical construction or conceptual analysis, or any combination of these, will provide a satisfactory answer” as to how we arrive at this moral knowledge. Even if we could somehow discover the moral quanta, it poses a further problem as to how this mysteriously-grasped object is related to the action in question. Mackie, like Ayer, echoes Hume. If we cannot ground our concepts in empirical experiences, he claims, in primary impressions, then commit them to the fire—or subject them to the argument from queerness. And, of course, fall into an inescapable pit of nominalism.
 Hume 1748: An Enquiry Concerning Human Understanding, §12.11-12, 134-35.
 This road to doubt-filled idealism, Deely explains (2001: Four Ages of Understanding, 522-35), begins with a divergence in the way modern philosophy treats sense qualities. In short, if what modernity terms the “secondary sensibles”—what medieval philosophy called the “proper sensibles”, such as taste, color, sound, and all the other sensory experiences which belong to one or another sense—are “phantoms” of the mind, incapable of being verified as actually belonging in any way to the external world, and if the “primary sensibles” (medieval philosophy’s “common sensibles”) are dependent upon the secondary sensibles, then the entirety of what is sensible is incapable of being known, and as, Hume says, the mind “cannot possibly reach any experience of [its perceptions’] connexion with objects.”
 Hume 1748: Enquiry, §2.3, 15.
 Hume 1748: Enquiry, §2.5, 16.
 Note that what Hume calls “perceptions” corresponds to what Locke calls “ideas”; Hume making a distinction not made by Locke between impressions, which are primary, and ideas, which are formed through reflection. Thus, a simple idea formed through sensation in Locke corresponds to an impression in Hume, and a simple idea formed through reflection in Locke to an idea in Hume.
 Hume 1748: Enquiry, §2.9, 18.
 Hume 1737: Treatise of Human Nature, 469. The spelling has been modernized by the author.
 Hume 1737: Treatise of Human Nature, 467-68: “I would fain ask any one, why incest in the human species is criminal, and why the very same action, and the same relations in animals have not the smallest moral turpitude and deformity? If it be answered, that this action is innocent in animals, because they have not reason sufficient to discover its turpitude; but that man, being endowed with that faculty, which ought to restrain him to his duty, the same action instantly becomes criminal to him; should this be said, I would reply, that this is evidently arguing in a circle. For before reason can perceive this turpitude, the turpitude must exist; and consequently is independent of the decisions of our reason, and is their object more properly than their affect. According to this system, then, every animal, that has sense, and appetite, and will; that is, every animal must be susceptible of all the same virtues and vices, for which we ascribe praise and blame to human creatures. All the difference is, that our superior reason may serve to discover the vice or virtue, and by that means may augment the blame or praise: But still this discovery supposes a separate being in these moral distinctions, and a being, which depends only on the will and appetite, and which, both in thought and reality, may be distinguished from the reason. Animals are susceptible of the same relations, with respect to each other, as the human species, and therefore would also be susceptible of the same morality, if the essence of morality consisted in these relations. Their want of a sufficient degree of reason may hinder them from perceiving the duties and obligations of morality, but can never hinder these duties from existing; since they must antecedently exist, in order to their being perceived. Reason must find them, and can never produce them.”
 Hume 1737: Treatise of Human Nature, 468-69.
 Cf. Gilbert Harman 1977: “Ethics and Observation” in The Nature of Morality, (32a): “You can observe someone doing something, but can you ever perceive the rightness or wrongness of what he does? If you round a corner and see a group of young hoodlums pour gasoline on a cat and ignite it, you do not need to conclude that what they are doing is wrong; you do not need to figure anything out; you can see that it is wrong. But is your reaction due to the actual wrongness of what you see or is it simply a reflection of your moral ‘sense’, a ‘sense’ that you have acquired perhaps as a result of your moral upbringing?”
 Ayer 1936: Language, Truth, and Logic, 106.
 Ayer 1936: Language, Truth, and Logic, 112. Cf. 111: “in every case in which one would commonly be said to be making an ethical judgement, the function of the relevant ethical word is purely ‘emotive’. It is used to express feeling about certain objects, but not to make any assertion about them.”
 Mackie 1977: “The Subjectivity of Values” in Ethics: Inventing Right and Wrong, (29b-30a): “If we admit what Hume calls the mind’s ‘propensity to spread itself on external objects’’ we can understand the supposed objectivity of moral qualities as arising from what we can call the projection or objectification of moral attitudes.”
 Mackie 1977: “The Subjectivity of Values” (26a).
 Mackie 1977: “The Subjectivity of Values” (28a).
 Ibid, (28a).
 Mackie 1977: “The Subjectivity of Values”, (29a): “What is the connection between the natural fact that an action is a piece of deliberate cruelty – say, causing pain just for fun – and the moral fact that it is wrong? It cannot be an entailment, a logical or semantic necessity. Yet it is not merely that the two features occur together. The wrongness must somehow be ‘consequential’ or ‘supervenient’; it is wrong because it is a piece of deliberate cruelty. But just what in the world is signified by this ‘because’? … It is not even sufficient to postulate a faculty which ‘sees’ the wrongness: something must be postulated which can see at once the natural features that constitute the cruelty, and the wrongness, and the mysterious consequential link between the two.”
 Hume 1748: Enquiry, §12.34, 144: “When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: For it can contain nothing but sophistry and illusion.”
 Mackie 1977: “Subjectivity of Values”, (28b): “If some supposed metaphysical necessities or essences resists such treatment, then they too should be included, along with objective values, among the targets of the argument from queerness.”