This post will begin a series that examines David Hume’s An Enquiry Concerning Human Understanding.
Hume begins with some general comments about why philosophy is worth doing: we have curiosity, and there is nothing wrong with pleasure of satisfying it. Besides, doing philosophy allows one sharpen their ability to find truth, and it is undoubtable that a such an ability can be used in other, more practical areas:
“We may observe, in every art or profession, even those which most concern life or action, that a spirit of accuracy, however acquired, carries all of them nearer their perfection, and renders them more subservient to the interests of society. And though a philosopher may live remote from business, the genius of philosophy, if carefully cultivated by several, must gradually diffuse itself throughout the whole society, and bestow a similar correctness on every art and calling. The politician will acquire greater foresight and subtility, in the subdividing and balancing of power; the lawyer more method and finer principles in his reasonings; and the general more regularity in his discipline, and more caution in his plans and operations. The stability of modern governments above the ancient, and the accuracy of modern philosophy, have improved, and probably will still improve, by similar gradations.”
Hume then explains that this book will be an attempt to understand how the mind works:
“May we not hope, that philosophy, if cultivated with care, and encouraged by the attention of the public, may carry its researches still farther, and discover, at least in some degree, the secret springs and principles, by which the human mind is actuated in its operations? Astronomers had long contented themselves with proving, from the phaenomena, the true motions, order, and magnitude of the heavenly bodies: Till a philosopher, at last, arose, who seems, from the happiest reasoning, to have also determined the laws and forces, by which the revolutions of the planets are governed and directed. The like has been performed with regard to other parts of nature. And there is no reason to despair of equal success in our enquiries concerning the mental powers and economy, if prosecuted with equal capacity and caution. It is probable, that one operation and principle of the mind depends on another; which, again, may be resolved into one more general and universal: And how far these researches may possibly be carried, it will be difficult for us, before, or even after, a careful trial, exactly to determine.”
He begins his path to understanding the mind by observing that there are two basic kinds of perceptions that we have: we have ideas of things, and we have sensory experience of things. In other words, your mind is acquainted with things like colors, sounds, sensations, etc. and also ideas. Hume then begins the process of reducing the former to the latter; positing the thesis called the copy principle which says that ideas are just mental copies of sensations we have experienced. There’s a pretty obvious objection to this though: what about monsters, aliens, fictional characters and the like? These are not things which are out there in the real world (or if they are, they aren’t things we’ve ever experienced) and yet people do have ideas of them. How could this be if ideas are nothing more than copies of sensory experience? Hume posits an explanation:
“But though our thought seems to possess this unbounded liberty, we shall find, upon a nearer examination, that it is really confined within very narrow limits, and that 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. When we think of a golden mountain, we only join two consistent ideas, gold, and mountain, with which we were formerly acquainted.”
There is, however, a problem with even this position, as Hume himself noted:
“Suppose, therefore, a person to have enjoyed his sight for thirty years, and to have become perfectly acquainted with colours of all kinds except one particular shade of blue, for instance, which it never has been his fortune to meet with. Let all the different shades of that colour, except that single one, be placed before him, descending gradually from the deepest to the lightest; it is plain that he will perceive a blank, where that shade is wanting, and will be sensible that there is a greater distance in that place between the contiguous colours than in any other. Now I ask, whether it be possible for him, from his own imagination, to supply this deficiency, and raise up to himself the idea of that particular shade, though it had never been conveyed to him by his senses?”
Many philosophers have wondered if this doesn’t pose a big problem for Hume. After all, if you can imagine a shade of blue that you’ve never seen, then how could be that ideas are just copies of sensations one has previously experienced? I suspect Hume’s copy thesis is at least a little off the mark. In the process of doing a little research for this, I wondered whether or not people who had been blind from birth might not have some idea of what it is like to see. Perception occurs in the brain. The blind may have something wrong with their eyes, but not with their brain. Their brain, then, ought to have the same potential to experience red and green as any other brain. Could that potential to experience be activated by something besides signals being sent from the eyes to the brain? Perhaps a neurosurgeon could stimulate just the right area of the brain and produce visual sensations in a blind person. If that’s the case, might it not be possible for a blind person’s brain to somehow activate the potential for color experience on its own? I suspect so (partially because it’s intuitive, partially because I found a forum post by a blind man claiming to know what colors are). The potentials for what we can experience must be things we are born with, and those potentials could be actualized inside someone’s mind without any stimulation of their nerves by the external world. On the other hand, something that Hume failed to realize was that the man’s thought of the shade of blue was itself a kind of sensory experience, albeit one generated from inside his own mind. I think it is true that ideas are made up of sense experiences, but we need not have had those sense experiences stimulated by the outside world in order for us to be acquainted with them. Any innate ideas we have will only be those of sensory experience. If you’re old enough to read this, you’ve probably already experienced all of the various colors and basic sensations like that, and I suspect that all ideas, innate or otherwise, boil down to those. This thesis, I think, works well enough to suit all of Hume’s philosophical aim:
“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. By bringing ideas into so clear a light we may reasonably hope to remove all dispute, which may arise, concerning their nature and reality.”
