[I am resuming my weekly philosophy of economics posts. This Fall I am on Sabbatical at Santa Barbara where I am teaching a course on Spinoza's Ethics and drafting a monograph on Adam Smith. So, expect a lot of Spinoza and/or Smith, but I'll try to engage with more recent economics, too.--ES]
Friday, Andy Clark, who is a Sage Fellow here in Santa Barbara, gave a lovely talk to the philosophy department. I quote a few lines from the abstract: "Perception, according to an emerging vision in computational cognitive neuroscience, is largely a matter of prediction. Full-blown visual perception, if these approaches (for a wide-ranging, non-technical review, see Kveriga et al (2007)) are correct, involves meeting incoming visual information with a matching flurry of top-down predictions that match (and thus ‘explains away’) the evolving visual signal across multiple spatial and temporal scales." Clark's account relied on recent work in Bayesian modeling of neural networks. In Q&A, I pressed Clark on the extreme inductivism of these Bayesian networks. But here I want to share another train of associations; Clark's model of the brain is partially anticipated in a passage in Adam Smith that has long fascinated me. (This past year I gave a number of talks about it.)
Adam Smith is often treated as a follower of David Hume. The first two sentence in the passage below, (which is from Smith's The History of Astronomy [first published in 1795]--one of my favorite works in the history of philosophy--), are straight out of Hume. But then Smith adds a further thought that is un-Humean in at least three respects. I quote in full before I end with a brief comment
"When two objects, however unlike, have often been observed to follow each other, and have constantly presented themselves to the senses in that order, they come to be so connected together in the fancy, that the idea of the one seems, of its own accord, to call up and introduce that of the other. If the objects are still observed to succeed each other as before, this connection, or, as it has been called, this association of their ideas, becomes stricter and stricter, and the habit of the imagination to pass from the conception of the one to that of the other, grows more and more rivetted and confirmed. As its ideas move more rapidly than external objects, it is continually running before them, and therefore anticipates, before it happens, every event which falls out according to this ordinary course of things. When objects succeed each other in the same train in which the ideas of the imagination have thus been accustomed to move, and in which, though not conducted by that chain of events presented to the senses, they have acquired a tendency to go on of their own accord, such objects appear all closely connected with one another, and the thought glides easily along them, without effort and without interruption. They fall in with the natural career of the imagination; and as the ideas which represented such a train of things would seem all mutually to introduce each other, every last thought to be called up by the foregoing, and to call up the succeeding; so when the objects themselves occur, every last event seems, in the same manner, to be introduced by the foregoing, and to introduce the succeeding. There is no break, no stop, no gap, no interval. The ideas excited by so coherent a chain of things seem, as it were, to float through the mind of their own accord, without obliging it to exert itself, or to make any effort in order to pass from one of them to another.
But if this customary connection be interrupted, if one or more objects appear in an order quite different from that to which the imagination has been accustomed, and for which it is prepared, the contrary of all this happens. We are at first surprised by the unexpectedness of the new appearance, and when that momentary emotion is over, we still wonder how it came to occur in that place. The imagination no longer feels the usual facility of passing from the event which goes before to that which comes after. It is an order or law of succession to which it has not been accustomed, and which it therefore finds some difficulty in following, or in attending to. The fancy is stopped and interrupted in that natural movement or career, according to which it was proceeding."
Now, in Hume I have been unable to find the claim that our ideas move more rapidly than our ideas, although it certainly is consistent with Hume. But the idea that the mind is constantly anticipating the world is -- while neo-Humeanhttp://www.typepad.com/site/blogs/6a00d8341ef41d53ef0133f3df26ed970b/post/compose -- I think original with Smith. In particular, and this was also emphasized by Clark, once 'trained-up' on a stable environment, the mind is on auto-pilot. It can safely predict its on state and doesn't need to exert itself. In his talk, Clark characterized this state of mind very nicely as "controlled hallucinations." [Smith's views on refined superstition are not far from this, but about that some other time.] Smith is very clear that if we are put in extremely unusual environments we stop functioning altogether. (cf "Could we conceive a person of the soundest judgment, who had grown up to maturity, and whose imagination had acquired those habits, and that mold, which the constitution of things in this world necessarily impress upon it, to be all at once transported alive to some other planet, where nature was governed by laws quite different from those which take place here; as he would be continually obliged to attend to events, which must to him appear in the highest degree jarring, irregular, and discordant, he would soon feel the same confusion and giddiness begin to come upon him, which would at last end in the same manner, in lunacy and distraction. Neither, to produce this effect, is it necessary that the objects should be either great or interesting, or even uncommon, in themselves.") It's only when unexpected stimuli interrupt the natural train of thought that the mind needs to work according to Clark and Smith. Now, at this points Smith insists that emotions (surprise, admiration, and wonder especially) do the job of activating a mental response--something that was missing from Clark's talk, but certainly compatible with his view. [One caveat: in Clark's model the brain is 'predicting' its current state [lower down the network hierarchy], while in Smith's approach the brain is predicting future events.']