Jonathan’s reaction to Susan Jacoby’s outburst is carefully arch about Holmes’ theory of mind. (I need to point out quickly that this is not about being stupid, but being ignorant, as Jacoby recognizes, though whether wilful ignorance is itself stupid or ignorant or both is more complicated: see below.)
Holmes’ logic is seductive in the same way as Calvin’s Dad’s, and has exactly the same scope of application, namely entertainment, but it’s many steps closer to being serious (my mother had, or averred, approximately Holmes’ finite closet theory of learning). It’s worth taking seriously the question of why smart is better than dumb (not much debate about that, actually) and whether one should identify an optimal distribution of ignorance across things one might learn so as not to waste resources on stuff that isn’t useful.
The technical analysis of this problem is called preposterior analysis in decision theory, and attends to the question of paying for information [information is never free; even this blog costs you the time to read it] that might raise your odds of properly making a choice that will work out well if the world is one way but badly if it’s another. It’s well developed and you can find it in any decision theory textbook.
This analysis recognizes that if you think the world is in state A and not B before buying any data D, and if the data is relevant to knowing whether A or B is the case, you must expect that the data will confirm what you already “know”. The more certain you are of A, the less likely you will be to buy information about it even though, if D were to come up “B!”, you might profit mightily or avoid a terrible mistake. Thus, one respectable basis on which you can skip Ann Coulter and stick with the RBC. However, the value of information depends on two blades of a scissors: the cost of being wrong and the likelihood that you are currently wrong both count. Information theory scores the most unlikely message, if received, with the highest content.
Psychologically, things are not so simple. Having your prejudices confirmed is comfortable and reassuring; having them challenged is arousing and irksome, so the wise will constantly resist short-term impulses to wallow in what they already believe, along with the signals to fress out on salt, sugar and fat. A better justification for vacuuming up a wide scope is that being smart, according to research I’ve lost track of but a reader might (bleg, bleg) point me at, is mostly a matter of two states, and one property that might be a trait but might be learnable: (i) knowing a lot of (ii) different kinds of stuff, and (iii) being mentally loosely wired so these things bump up against each other across filing categories. Even if we can’t do much about (iii), (i) and (ii) are not traits and we can increase them, so if smart is indeed better than dumb, being less ignorant broadly can make you smarter, and Holmes is wrong to think he can tell whether something he doesn’t know yet might be just the thing for a question he hasn’t confronted yet.
There’s the issue of the obviously finite capacity of the brain in bytes. Sure, but is anyone actually at the point of filling it up? If we crudely estimate one bit per neuron, a fast reader (400 words per minute) would take ten years reading every waking hour of every day to do it. Anyway, the brain is good at erasing old “tapes” you haven’t watched in a long time to reuse for new stuff. The best analogy to this argument is the claim that a production-possibility frontier constrains any organization to trade off ruthlessly between cost and quality. As Bob Leone used to point out, nothing in this theory shows that any real organization is at that frontier, and there are lots of reasons why it isn’t, so we should assume we can make things better and cheaper both (Toyota), rather than pacing back and forth inside an imagined constraint (GM). Nine times out of ten, the PPF is pretty far away, so we can win both ways and (for example) teach students more and do more (better) research both.
Jacoby is right on the facts, as far as I can tell from shrinkage in the resources college students are able to draw on to make their points or explore issues with, assessed over decades. And she’s right to deplore the trend. Between that one and global warming, my anxiety plate is piled pretty high.