Michael Masinter writes:
As a longtime blog reader sufficiently wise not to post beyond my academic discipline, I hope you might take a look at what seems to me to be a highly controversial attempt to use regression analysis to blame the ACLU for the recent rise in homicides in Chicago. A summary appears here with followup here. I [Masinter] am skeptical, but loathe to make the common mistake of assuming that my law degree makes me an expert in all disciplines. I’d be curious to know what you think of the claim.
The research article is called “What Caused the 2016 Chicago Homicide Spike? An Empirical Examination of the ‘ACLU Effect’ and the Role of Stop and Frisks in Preventing Gun Violence,” and is by Paul Cassell and Richard Fowles.
I asked Masinter what were the reasons for his skepticism, and he replied:
Two reasons, one observational, one methodological, and a general sense of skepticism. Other cities have restricted the use of stop and frisk practices without a corresponding increase in homicide rates. Quite a few variables appear to be collinear. The authors claim that Bayesian Model Averaging controls for that, but I lack the expertise to assess their claim. More generally, their claim of causation appears a bit like post hoc propter hoc reasoning dressed up in quantitative analysis. Perhaps I am wrong, but I have come to be skeptical of such large claims.
I asked Masinter if it would be ok to quote him, and he responded:
Yes, but please note my acknowledged lack of expertise. Too many of my law prof colleagues think our JD qualifies us as experts in all disciplines, a presumption magnified by our habit of advocacy.
I replied, “Hey, don’t they know that the only universal experts are M.D.’s and, sometimes, economists?”, and Masinter then pointed me to this wonderful article by Arthur Allen Leff from 1974:
With the publication of Richard A. Posner’s Economic Analysis of Law, that field of learning known as “Law and Economics” has reached a stage of extended explicitness that requires and permits extended and explicit comment. . . . I was more than half way through the book before it came to me: as a matter of literary genre (though most likely not as a matter of literary influence) the closest analogue to Economic Analysis of Law is the picaresque novel. Think of the great ones, Tom Jones, for instance, or Huckleberry Finn, or Don Quixote. In each case the eponymous hero sets out into a world of complexity and brings to bear on successive segments of it the power of his own particular personal vision. The world presents itself as a series of problems; to each problem that vision acts as a form of solution; and the problem having been dispatched, our hero passes on to the next adventure. The particular interactions are essentially invariant because the central vision is single. No matter what comes up or comes by, Tom’s sensual vigor, Huck’s cynical innocence, or the Don’s aggressive romanticism is brought into play . . . Richard Posner’s hero is also eponymous. He is Economic Analysis. In the book we watch him ride out into the world of law, encountering one after another almost all of the ambiguous villains of legal thought, from the fire-spewing choo-choo dragon to the multi-headed ogre who imprisons fair Efficiency in his castle keep for stupid and selfish reasons. . . . One should not knock the genre. To hold the mind-set constant while the world is played in manageable chunks before its searching single light is a powerful analytic idea, the literary equivalent of dropping a hundred metals successively into the same acid to see what happens. The analytic move, just as a strategy, has its uses, no matter which mind-set is chosen, be it ethics or psychology or economics or even law. . . .
Leff quotes Posner:
Efficiency is a technical term: it means exploiting economic resources in such a way that human satisfaction as measured by aggregate con- sumer willingness to pay for goods and services is maximized. Value too is defined by willingness to pay.
And then Leff continues:
Given this initial position about the autonomy of people’s aims and their qualified rationality in reaching them, one is struck by the picture of American society presented by Posner. For it seems to be one which regulates its affairs in rather a bizarre fashion: it has created one grand system—the market, and those market-supportive aspects of law (notably “common,” judge-made law)—which is almost flawless in achieving human happiness; it has created another-the political process, and the rest of “the law” (roughly legislation and administration)—which is apparently almost wholly pernicious of those aims. An anthropologist coming upon such a society would be fascinated. It would seem to him like one of those cultures which, existing in a country of plenty, having developed mechanisms to adjust all intracultural disputes in peace and harmony, lacking any important enemies, nevertheless comes up with some set of practices, a religion say, simultaneously so barbaric and all-pervasive as to poison almost every moment of what would otherwise appear to hold potential for the purest existential joy. If he were a bad anthropologist, he would cluck and depart. If he were a real anthropologist, I suspect he would instead stay and wonder what it was about the culture that he was missing. That is, he would ponder why they ‘manted that religion, what was in it for them, what it looked like and felt like to be inside the culture. And he would be especially careful not to stand outside and scoff if, like Posner, he too leaned to the proposition that “most people in most affairs of life are guided by what they conceive to be their self-interest and . . . choose means reasonably (not perfectly) designed to promote it.”
I’m reminded of our discussion from a few years ago regarding the two ways of thinking in economics.
Economists are often making one of two arguments:
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People are rational and respond to incentives. Behavior that looks irrational is actually completely rational once you think like an economist.
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People are irrational and they need economists, with their open minds, to show them how to be rational and efficient.
Argument 1 is associated with “why do they do that?” sorts of puzzles. Why do they charge so much for candy at the movie theater, why are airline ticket prices such a mess, why are people drug addicts, etc. The usual answer is that there’s some rational reason for what seems like silly or self-destructive behavior.
Argument 2 is associated with “we can do better” claims such as why we should fire 80% of public-schools teachers or Moneyball-style stories about how some clever entrepreneur has made a zillion dollars by exploiting some inefficiency in the market.
Despite going in the opposite directions, Arguments 1 and 2 have a similarity, in that both used to make the point that economists stand from a superior position by which they can evaluate the actions of others.
But Leff said it all back in 1974.
P.S. We seem to have mislaid our original topic, which is the study of the change in homicide rates in Chicago. I read the article by Casell and Fowles and their analysis of Chicago seemed reasonable to me. At the same time, I agree with Masinter that the comparisons to other cities didn’t seem so compelling.