The law of law’s leverage

Last week I posted on Owen Jones’s 2000 article Time-Shifted Rationality and the Law of Law’s Leverage: Behavioral Economics Meets Behavioral Biology and his argument that behavioural economics (and law) requires the theoretical backbone of evolutionary biology.

The second half of that article has a neat idea – what Jones calls the law of law’s leverage. The basic idea is that the effectiveness of laws will vary with the adaptiveness (in ancestral environments) of the behaviour the law is trying to change. Jones describes it as follows:

The law of law’s leverage predicts that less legal intervention will be necessary to shift a behavior in ways that tended to increase reproductive success in ancestral environments than will be necessary to shift behavior in ways that tended to decrease reproductive success in ancestral environments. Put another way, the slope of the demand curve for historically adaptive behavior that is now deemed to be socially (in some cases even individually) undesirable will be far steeper than the slope of the demand curve for behavior that was comparatively less adaptive in ancestral environments. Importantly, this relationship between the slopes will hold, even when the costs that an individual actually and foreseeably incurs in behaving in an historically adaptive way will exceed presently foreseeable benefits of such behavior

As an example:

Evolutionary analysis predicts that, and explains why, the slope of the demand curve for adulterous behavior is likely to be comparatively steep (as is the slope for most sexual behavior) and thus comparatively insensitive to the imposition of legal prohibitions (or other costs, such as effect on career). Evolutionary analysis also predicts that, and may help explain why, marriage, separation, divorce, and remarriage behavior will be less sensitive to legal changes than will be many other forms of behavior. Because, as we know, natural selection disfavors inbreeding among close relatives, evolutionary analysis also and separately predicts that it will be far less costly to discourage incest among parents and their natural children, and between siblings reared together, than among stepparents and stepchildren, and among stepchildren. Because we know that natural selection favors discriminative parental solicitude rather than indiscriminate parental solicitude (that is, it generally favors psychological mechanisms that bias resources toward offspring over non-offspring), we can explain and anticipate that the cost of reducing child abuse will be greater, per capita, for stepparent households than for non-stepparent households. Similarly, we can predict that men under court-order to provide child support payments for a child they know or suspect they did not father will be less likely to comply than will biological fathers.

Another nice example brings the point home strongly:

Take, for example, a hypothetical legal rule that required an adult, in a crisis situation involving both her children and the children of others, to save children in order of their ranked intelligence (or any other desirable characteristic), irrespective of her own relatedness to each. We know that such a legal rule would be absurd. But why? It is not because the rule would lead to inefficient outcomes. To the contrary, the outcome might increase social wealth compared to the alternative.

It is not enough to say that powerful social norms would generate irresistible emotions in the woman to save her own children, because it so happens that we would expect the same behavior from parents all over the world, regardless of the many vicissitudes of culture. We know the rule would be absurd because we intuitively sense that the preference to save one’s own child would be insensitive to variations in legal costs we might impose in an effort to shift the behavior—all over the planet, in every human culture. The theoretical basis for that sense of relative inelasticity of the demand for certain behaviors, in certain contexts, is not simply acculturation alone, but the law of law’s leverage, as derived from the effects of evolution on human behavior-biasing psychological predispositions.

The concept of the law of law’s leverage reminded me of a section in Steven Pinker’s The Blank Slate: The Modern Denial of Human Nature, when he pointed out that evidence of a biological basis to crime could be used both by advocates of stronger punishment and advocates of weaker punishment. Evidence of a biological disposition could be argued to reduce culpability. Alternatively, a strong disposition needs to be countered by even stronger incentives.

As such, the law of law’s leverage may lead us to look at a steep demand curve for a particular behaviour and acknowledge that we can’t change it. Or, we may want to massively change the price.

A week of links

Links this week:

  1. A few years old, but good – a story from a Blue Zone “where people forget to die”. HT: Razib Khan
  2. Another critique of modern dietary guidelines. Weight gain after a fecal transplant. And the US Government is about to drop warnings about cholesterol.
  3. Improving ‘Neoclassical man’ with a gaze heuristic.
  4. Bigger data sets are uncovering the genetic underpinnings of intelligence.
  5. A take on the Peter Principle.
  6. To what extent will new birth control options be another fertility shock?
  7. Yet more on lead and crime.
  8. Greg Clark on social mobility. And my review of his book.

And if you missed them, my posts this week:

  1. Will defaults lose their power in the digital age. Or, as put by Eric Crampton, Will nudges survive the Lucs Critique?
  2. I recommend using a story other than organ donation rates to support defaults.

A week of links

Links this week:

  1. We see skill where none exists and are happy to pay for transparently useless advice.
  2. No evidence of the effect of parenting on criminal behaviour.
  3. Doug Kenrick on testosterone and the rationality of taking risks.
  4. Pulling apart the recent paper on perceptions of ability and the gender gap.
  5. The human guinea pig.
  6. Distrust of vaccines not a left wing issue.

Manzi on the abortion-crime hypothesis

My recent reading of David Colander and Roland Kupers’s Complexity and the Art of Public Policy prompted me to re-read James Manzi’s Uncontrolled: The Surprising Payoff of Trial-and-Error for Business, Politics, and Society. I see the two books as riffs on a similar theme.

I’ll post a review of Uncontrolled later this week, but in the meantime, Manzi provides an interesting take on the Donohue-Levitt abortion-crime hypothesis. Their hypothesis is that abortion reduces crime as unwanted children are more likely to become criminals. As the legalisation of abortion increased access to abortion and decreased the number of unwanted children, decreases in crime through the 1990s and 2000s could be due to this legalisation.

Donohue and Levitt’s initial paper triggered a raft of responses, including one demonstrating an analytical error, which, once corrected for, resulted in the abortion-crime link disappearing. Donohue and Levitt then redid the work, and showed by recasting a few assumptions, the error could be corrected for and the link re-established. As Manzi states:

The revealing observation is not that there was an analytical error in the paper (which almost certainly happens far more often than we like to think), but that once it was found and corrected, it was feasible to rejigger the regression analysis to get back to the original directional result through various defensible tweaks to assumptions. If one could rule out either the original assumptions or these new assumptions as unreasonable, that would be better news for the technique. Instead we have a recipe for irresolvable debate.

Manzi also points out that Levitt, in his book Freakonomics (with Stephen Dubner), indirectly identified one of the reasons why Donohue and Levitt’s  claim is so tenuous:

In Freakonomics, Levitt and Dubner write that Roe [the Supreme Court decision in Roe v Wade establishing a right to abortion] is “like the proverbial butterfly that flaps its wings on one continent and eventually creates a hurricane on another.” But this simile cuts both ways. It is presumably meant to evoke the “butterfly effect”: meteorologist Edward Lorenz’s famous description of a global climate system with such a dense web of interconnected pathways of causation that long-term weather forecasting is a fool’s errand. The actual event that inspired this observation was that, one day in 1961, Lorenz entered .506 instead of .506127 for one parameter in a climate-forecasting model and discovered that it produced a wildly different long-term weather forecast. This is, of course, directly analogous to what we see in the abortion-crime debate and Bartels’s model for income inequality: tiny changes in assumptions yield vastly different results. It is a telltale sign that human society is far too complicated to yield to the analytical tools that nonexperimental social science brings to bear. The questions addressed by social science typically have none of the characteristics that made causal attribution in the smoking–lung cancer case practical.

A week of links

Links this week:

  1. Skip your annual physical.
  2. The phrase “Statistical significance is not the same as practical significance” is leading us astray.
  3. The ineffectiveness of food and soft drink taxes (although not all calories are the same). The latest extension of the nanny state – banning junk food from playgrounds. And a new book worth looking at – Government Paternalism: Nanny State or Helpful Friend? (HT: Diane Coyle)
  4. Marijuana in Colorado – no surprise that the most grandiose claims of both sides haven’t come to fruition.
  5. Even more on lead and crime.

A week of links

Links this week:

  1. Arnold Kling’s review of Complexity and the Art of Public Policy.
  2. Are some diets mass murder? HT: Eric Crampton
  3. Social conservatism correlates with lower cognitive ability test scores, but economic conservatism correlates with higher scores.”
  4. More on lead and crime.
  5. A risk averse culture. HT: Eric Crampton
  6. Welfare conditional on birth control.
  7. We may regret the eclipse of a world where 6,000 different languages were spoken as opposed to just 600, but there is a silver lining in the fact that ever more people will be able to communicate in one language that they use alongside their native one.” HT: Steve Stewart Williams
  8. If you want to feel older, read this. HT: Rory Sutherland

The eugenics of contraception

After copping some criticism for his comments on the coverage of female contraception in health insurance, Steven Landsburg has noted that some arguments in its favour may have merit. Two of the more interesting he notes are as follows:

We might not want to discourage parenthood in general, but surely we want to discourage parenthood by the sort of woman who won’t use contraception unless it’s subsidised. Ideally we’d tax childbirth among that class of women, but since they’re hard to identify, the best available policy is to subsidize contraception.

We might not want to discourage parenthood in general, but surely we want to discourage unwanted parenthood, because unwanted babies are far less socially valuable than wanted babies.

On the first argument, Landsburg is not convinced that the primary group who will change their behaviour are the poor or the dumb, or that we do not want them reproducing. However, he notes the second, which in some ways reflects the Levitt-Donohue abortion-crime theory, is an argument worth taking seriously. The two arguments are quite similar, however, as while Levitt and Donohue explained the abortion-crime effect in terms of unwanted parenthood, the theory is often quoted in the context of what type of people had the abortions.

However, what struck me about these arguments is that they are representative of an increasing tendency for discussions about tax or family policy, contraception and immigration to refer to the effects on the composition of the next generation. On the one hand, I find the subject interesting and have blogged about it before. On the other, if government started to actively consider factors such as these, I can only imagine the unintended consequences.

Crime, abortion and genes

First, from Donohue and Levitt’s The Impact of Legalized Abortion on Crime, which argued that the legalisation of abortion contributed to later declines in crime:

More interesting and important is the possibility that children born after abortion legalization may on average have lower subsequent rates of criminality for either of two reasons. First, women who have abortions are those most at risk to give birth to children who would engage in criminal activity. Teenagers, unmarried women, and the economically disadvantaged are all substantially more likely to seek abortions. Recent studies have found children born to these mothers to be at higher risk for committing crime in adolescence. Gruber, Levine, and Staiger, in the paper most similar to ours, document that the early life circumstances of those children on the margin of abortion are difficult along many dimensions: infant mortality, growing up in a single-parent family, and experiencing poverty. Second, women may use abortion to optimize the timing of child-bearing. A given woman’s ability to provide a nurturing environment to a child can fluctuate over time depending on the woman’s age, education, and income, as well as the presence of a father in the child’s life, whether the pregnancy is wanted, and any drug or alcohol abuse both in utero and after the birth. Consequently, legalized abortion provides a woman the opportunity to delay childbearing if the current conditions are suboptimal. Even if lifetime fertility remains constant for all women, children are born into better environments, and future criminality is likely to be reduced.

Second, from Bryan Caplan’s Selfish Reasons to Have More Kids:

Parents have little or no effect on criminal behavior. …

In 1984, Science published a study of almost 15,000 Danish adoptees age fifteen or older, their adoptive parents, and their birth parents. … As long as the adoptee’s biological parents were law abiding, their adoptive parents made little difference: 13.5 percent of adoptees with law-abiding biological and adoptive parents got convicted of something, versus 14.7 percent with law-abiding biological parents and criminal adoptive parents. If the adoptee’s biological parents were criminal, however, upbringing mattered: 20 percent of adoptees with law-breaking biological and law-abiding adoptive parents got convicted, versus 24.5 percent with law-breaking biological and adoptive parents. Criminal environments do bring out criminal tendencies. Still, as long as the biological parents were law abiding, family environment made little difference.

In 2002, a study of antisocial behavior in almost 7,000 Virginian twins born since 1918 found a small nurture effect for adult males and no nurture effect for adult females. The same year, a major review of fifty-one twin and adoption studies reported small nurture effects for antisocial attitudes and behavior. For outright criminality, however, heredity was the sole cause of family resemblance.

The lesson: Even if your standards are low, instilling character is hard. Genes are the main reason criminal behavior runs in families.

How much of the abortion-crime link (to the extent it is real) is driven by elimination of those more genetically predisposed to crime?

Cost-effective crime fighting

From an interview of Steven Pinker on the Freakonomics blog:

There are many statistical predictors of violence that we choose not to use in our decision-making for moral and political reasons, because the ideal of fairness trumps the ideal of cost-effectiveness. A rational decision-maker using Bayes’ theorem would say, for example, that one should convict a black defendant with less evidence than one needs with a white defendant, because these days the base rates for violence among blacks is higher. Thankfully, this rational policy would be seen as a moral abomination. I suspect that the same sentiments would prevent any policy from pre-judging a child based on the behavior of his parents, whether one thinks the connection is due to genes or to parenting.

A review of the arguments against immigration would suggest that many people have no qualms using a similar Bayesian argument in shaping their immigration policy preferences.

Also from the same interview, which focuses on Pinker’s recently released book The Better Angels of Our Nature: Why Violence Has Declined:

Yes, I present extensive statistics showing the non-state peoples (hunter-gatherers, hunter-horticulturalists, pastoralists, and others living outside the control of states) have far higher rates of violence than modern states, even at their worst. I think this very long prehistory of life under anarchy probably selected for motives that can continue to lead to violence today, particularly dominance and revenge, both of which are adaptive in a state of anarchy but not in societies with well-functioning systems for nonviolent dispute resolution. This does not mean that we harbor a thirst for blood which must periodically be discharged—even the most bellicose societies modulate their violence, and can live for decades in peace. Evolution gave us motives that impel us to violence, such as greed, dominance, revenge, and the urge to mete out moralistic punishment, but it also gave us motives that undermine or control the violent inclinations, such as self-control, empathy, and reason—the better angels of our nature.

Genetic thresholds

In yesterday’s post on crime, I quoted David Eagleman’s statement that “we may someday find that many types of bad behaviour have a basic biological explanation—as has happened with schizophrenia, epilepsy, depression, and mania.” What we now consider culpable behaviour may fall into the class of mental illness, with the criminal justice system adjusting its threshold so.

This threshold issue extends beyond crime. Take IQ, which is highly heritable and correlates with income and most other life outcomes. Where one sits on the IQ bell curve is largely determined by genes. If one’s IQ falls below a certain level, they may receive special schooling, social security and other forms of special care. As is the case for criminal culpability, a threshold is set which considers biological factors.

In each case, is may be worse for someone to be just above the threshold than just below it. It is the person that has a strong genetic disposition to commit crimes, but not strong enough for the justice system to consider it a mental illness, that is the most likely to end up behind bars. Similarly, it is the person with the very low IQ, but not low enough IQ to be considered disabled, that may have the worst life outcomes. The pay-out from the genetic lottery is not monotonic.