Let us fix our attention out of ourselves as much as possible; let us chase our imagination to the heavens, or to the utmost limits of the universe; we never really advance a step beyond ourselves, nor can conceive any kind of existence, but those perceptions, which have appear'd in that narrow compass. This is the universe of the imagination, nor have we any idea but what is there produc'd.
David Hume
Come with me and you'll be
In a world of pure imagination
Take a look and you'll see
Into your imagination
In a world of pure imagination
Take a look and you'll see
Into your imagination
David Hume is a curiosity. Philosophical adolescents of all ages thrill to his famously subversive doctrines concerning religion, causation, practical reason, value, the self, and metaphysics in general. And yet these doctrines rest on philosophical assumptions that are at best extremely controversial (such as the thesis that what is conceivable is possible) and at worst known to have been decisively refuted (such as the thesis that a concept is a kind of image) and even self-undermining (such as Hume’s Fork). Having been drawn and found agreeable, Hume’s conclusions persist, like zombies, beyond the death of the arguments that led to them.
It is especially ironic that people who think of themselves as staunchly objective, guided by rational argument grounded in the hard earth of observable reality, should regard Hume as a hero. For Hume’s philosophy destroys reason and experience alike, effectively reducing both to the entirely subjective arena of imagination. Hume’s is a realm of unreality -- he is Willy Wonka without the chocolate, but only impressions and ideas of chocolate.
As is well known to regular readers of this blog, Scholastics and other Aristotelians distinguish the faculties of sensation, imagination, and intellect. Sensation is what you deploy when you have a perceptual experience of (say) a certain man. Now though you are aware of the man by means of a percept of the man, it is for the Aristotelian the man himself, and not the percept, that is the object of sensory experience. Hallucinations and the like do not cast doubt on this, any more than the fact that this or that dog might be missing a leg casts doubt on the proposition that dogs have four legs. A three-legged dog is a damaged or abnormal dog and thus precisely notwhat you should look to if you’re interested in determining the nature of dogs. Similarly, a hallucination is an abnormal perceptual experience, and one typically resulting from some sort of damage or dysfunction. It is thus precisely the sort of thing you should not look to in order to discover the nature of normal sensory experience. A philosopher who takes hallucinations, illusions, and the like to “show” that the objects of sensation are not really external objects is like a biologist who takes the existence of three-legged dogs to “show” that dogs don’t naturally have four legs.
Imagination is what you deploy when you form mental images or phantasms of what you’ve seen, heard, touched, smelled, and tasted. Hence as you sit back relaxing one evening you might call to mind what a certain man you saw that day looked like, what his voice sounded like, what his handshake felt like, and so forth. Though the man and his qualities all exist outside your mind, they are not immediately present to you as you sit there imagining them. And of course you might form images of men you have not actually perceived and who do not exist. For instance, you might imagine a man that is like the one you saw but five feet taller, or with red hair rather than black, or who wears a colorful costume and fights crime, or who has wings. In general, in imagination we can separate out various aspects of the things we’ve perceived -- this or that color, shape, sound, texture, flavor, odor, or what have you -- and recombine them in all sorts of novel ways. As these facts indicate, imagination has a subjective character that distinguishes it from sensory experience.
Intellect is what you deploy when you grasp the concept of a man, when you put this concept together with others to form a judgment (such as the judgment that all men are mortal), and when you reason from one judgment to another in a logical way (as when you think all men are mortal, so the man I met today is mortal). Concepts, and the acts of judgment and reasoning that presuppose them, are irreducible to what sensation and imagination are capable of, for reasons I’ve set out many times (e.g. briefly here, and at systematic length here). Concepts have a universal reference that no percept or image can have; they can be determinate, precise, or unambiguous in their content in a way no percept or image can be; and we can form concepts of things which can in no way be perceived or imagined. Like sensation, intellect is objective, but in a different way. Sensation reveals to us only particular things that exist independently of our minds. The intellect grasps natures that are universal, existing not only in the particular things we perceive but in things we have not perceived and never could perceive.
Now, Hume essentially collapses both intellect and sensation into imagination. Start with intellect. Hume, like Berkeley, reduces concepts to mental images together with general names. Ever since Wittgenstein’s critique of classical empiricism, it seems generally to have been acknowledged among analytic philosophers that this account of concepts is hopeless, but any Scholastic could have told them the same. And this mistake of Hume’s underlies his accounts of causation, substance, and other basic metaphysical notions. The suggestion that we have no clear concept of causal connection, substance, etc. only seems plausible if we think of having a concept of these things as a matter of being able to form some kind of mental image of them. Once that assumption is abandoned, the force of the arguments dissipates. And the knowledge of arithmetic and geometry available even to a child suffices to show just how stupid the assumption is. To have the concept of a triangle is not a matter of having any sort of mental image, since what we can imagine is only ever this or that particular sort of triangle rather than triangularity in the abstract. Nor is it to have an image of the word “triangle,” since that word is only contingently connected with what it refers to. (To have the concept triangle is to have the very same thing Euclid had, even though he did not know the English word “triangle.”) Similarly, knowing that 2 + 2 = 4 is not a matter of forming images of the shapes “2,” “+,” etc., since those symbols too are only contingently related to the strictly unimaginable realities they name.
(Nor are these realities to be thought of on the model of any of the ghostly objects of empiricist and materialist caricature -- ectoplasm, magic fairy dust, or whatever -- all of which are things which can be imagined in the sense that we can form mental images of them. Skeptics who attack such sophomoric caricatures are missing the whole point, insofar as they assume that to make sense of something we have to be able to regard it as the sort of thing that could at least in principle be seen, heard, tasted, touched, or smelled. But whether that is the case is, of course, precisely what is at issue. Nor would mathematics and science be possible if it were the case.)
Hume also effectively reduces sensation to imagination insofar as he strips the former of its objectivity. For Hume there are in the mind only impressions and ideas, where the former are what we are aware of in sensation and the latter the faint copies of impressions that are formed in imagination. But impressions have no essential connection to anything mind-independent. When you perceive a man it is really only the impressions associated with the man -- these colors, those shapes, etc. -- that you perceive, and you cannot know one way or the other whether there is anything external to the mind which corresponds to them. They are thus as subjective as mental images. Indeed, while Hume characterizes an “idea” or image as a less vivid version of an impression, you could just as well characterize an impression as a more vivid version of an idea or image.
Impressions are also image-like in that they are more or less conceived of in a manner similar to the “pulled apart” elements that imagination recombines as it likes. Again, it isn’t strictly a man of which one has a Humean impression. It is rather a set of color patches, shapes, sounds, etc., which the mind combines and labels “man.” This too is a model contemporary analytic philosophers know to be hopelessly crude, and have known it ever since Wilfrid Sellars’ attack on the “myth of the given.” Hume takes a perceptual experience to be reducible to an aggregate of impressions, but the notion of a Humean impression is itself an abstraction from an actual experience. When you read a book it is a book that you are perceiving, not a whitish rectangular expanse, a feeling of smoothness, a sound as of paper crinkling, etc. These “impressions” are not more basic than the experience as a whole, any more than a foot or a kidney is more basic than the organism of which they are parts. On the contrary, organisms are more basic than their organs, and the latter have to be understood in light of the former rather than the other way around. “Impressions” and the like are related to ordinary perceptual experiences in the same way. Hence analyzing perceptual experiences in terms of Humean impressions gets things the wrong way around.
It is no surprise, then, that for Hume neither intellect nor sensation can ever “advance a step beyond” that “narrow compass” of “the universe of the imagination” -- that is, beyond “ourselves.” There is only the play of subjective appearances available to you here and now. Some of them you take to comprise a particular material object really existing external to your mind, some of them to amount to concepts and truths that apply far beyond not only what is outside your mind here and now but even beyond anything you have experienced or will experience. But all of that is illusion, or at least the supposition that you have any reason whatsoever to believe any of that is in Hume’s view an illusion. Nor is it any surprise that, once again to quote Willy Wonka channeling Hume, in a “world of pure imagination… what we'll see will defy explanation.” For explanation requires the intellect to grasp what sensation and imagination cannot -- objective causal connections, the essences of things, and so forth -- all of which go by the board in Hume’s philosophy.
What is surprising is that anyone would still take seriously Hume’s doctrines given the fallaciousness of the arguments on which they rest. Or rather, it is not surprising at all. Like the imagined religious believers at whom he so often directs his contempt, the Humean skeptic knows in advance the conclusions he wants to reach, and isn’t too particular about how he gets there. He wants a world in which causation will not get him to an Uncaused Cause, in which good and bad are not objective features of reality but mere sentiments, nor rationality anything more than the slave of the passions. For as Willy Wonka tells us, in a Humean world, a world of pure imagination:
Anything you want to, do it
Want to change the world, there's nothing to it.
Want to change the world, there's nothing to it.