Is Meat Bad for You?

I came across a convincing critique of the recent headlines claiming that eating eat greatly increases your chance of dying. The discussion is fairly detailed; the critic pretty clearly doesn't believe that the conclusions reported can be consistent with the data, given what appear to be internal inconsistencies: A larger effect after controlling for other factors then before, despite the fact that the other factors are mostly getting worse as the amount of meat eaten increases. 

But the real killer fact is much simpler. The studies reported on covered two groups of people over a period of more than twenty years. Total mortality from all causes was less than one percent. So what is being reported as a 13% increase in mortality due to eating one more serving of meat is, assuming everything in the study is correct, a 13% increase in a mortality rate of less than one percent, or an additional mortality of about one in a thousand over twenty plus years. 

I also found another piece offering a more general criticism of results of this sort—claims about the effect of nutrition based on studies of what some large group of people ate and what happened to them. Such results are often newsworthy but, at least according to the author of that piece, always or almost always fail to be supported by followup studies.

Correction:

Looking at the reports more carefully, I think the critique is wrong in at least one important respect. The death rate is not less than 1% for the whole study period, it is less than 1% per year. The total death rate over the period appears to be about 20%, which greatly weakens the force of the argument I cited.

Nordhaus on Global Warming

A correspondent points me at the work of Nordhaus and Boyer, attempting to estimate the externality from CO2 production and the appropriate response. I have not read the printed version, but there is a webbed version available. A number of things strike me:

1. Their conclusion is that 

"current approaches, such as the Kyoto Protocol, are highly inefficient, with abatement costs approximately ten times their benefits in reduced damages."

2. In order to get even that result, they depend on including costs from a very uncertain estimate of the risk that global warming will result in low probability catastrophes of one sort or another: 

"this approach is taken because of the finding of the first-generation studies that the impacts on market sectors are likely to be relatively limited."

Or in other words, without including the costs from such catastrophic risks, global warming doesn't seem to be a serious problem.

3. They estimated the cost from low probability catastrophes by asking a lot of experts how likely they thought it was that there would be a catastrophe, assuming a given rise in global temperature, that would reduce world GNP by at least 25%.

Even if one takes seriously the output of that sort of procedure, there is a striking asymmetry in their approach. They do not appear to have asked any experts what the chance is that preventing global warming would cause a catastrophe—or, to put it differently, that global warming will prevent one. Yet, as I keep pointing out, earth's climate was not designed for us, hence there is no a priori reason to assume that large negative results due to a few degrees of warming are more likely than large positive ones.

This is a striking illustration of my general critique of the "add up the externalities" approach to policy issues. Possible changes can have both positive and negative effects. If you want to conclude that something should be prevented, you focus on the negative effects, ignore or minimize the positive ones, and claim to have an objective argument to support your conclusion. That is precisely what Nordhaus and Boyer have done. The only surprising part is that, even after doing that, they still got only a weak version of the (presumably) desired conclusion.

This leaves me wondering what the pro-global warming view of Nordhaus and Boyer is. Their conclusion  weakens the case for something like the Kyoto protocol--and that conclusion hinges on a procedure that cannot, I think, be defended. Correct that error and their work appears to provide no support for any substantial effort to prevent global warming.

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P.S. After writing this, it occurred to me that there is one respect in which I am being too hard on Nordhaus and Boyer. Suppose we limit "catastrophes" to changes that are not only unlikely and very large, but also very fast. Then there really is some asymmetry to the situation. Humans are currently optimized against the current environment, making any change presumptively negative. I have argued in the past that that is not a strong argument with regard to changes that occur slowly—for example three degrees of warming in a century—since humans will in any case be changing what they do in many ways over so long a period. But that argument would not apply to a change that occurred over only a few years.

If, for instance, climate change makes Europe unbearably cold but adds an equal amount of acceptable land elsewhere, say in northern Canada, and does it in only a couple of years, there will be a very large net cost.

So they would have a legitimate case if they limited their category of catastrophes to rapid ones—but, so far as I can tell from what they wrote, they did not.

Iceland, Shari'a, and the Reliability of Oral Transmission

I have recently been reading up on the history of Islamic law, in particular in Knut Vikør's excellent Between God and the Sultan, for my current book project on legal systems very different from ours. While doing so, it occurred to me that there is at least one issue common to scholarly debates on that subject and debates on the legal system of saga period Iceland, the subject of a different chapter of my book. That issue is the reliability of oral transmission of a prose text.

In the Icelandic case, the question is part of a very old scholarly debate on the origin of the sagas. The family sagas describe events of the tenth and early eleventh centuries. Their texts, however, were written in the thirteenth and early fourteenth centuries. Were they composed at the time, using bits and pieces of the earlier history, in which case their description of the earlier society may largely reflect later conditions, or were they composed shortly after the events they describe, transmitted orally, and finally committed to writing?

The strongest evidence against the latter theory is that, while the sagas sometimes have skaldic verse embedded in them, they are themselves prose documents. Reliable oral transmission over a period of centuries is more plausible for verse, a point actually mentioned by Snorri Sturluson in his introduction to Heimskringla, his saga history of the Norwegian kings. 

Jesse Byock, a leading modern scholar, has offered some ingenious evidence on the other side. The hero of Egilsaga (one of my favorite sagas), his father and his grandfather exhibit a set of traits that fit the symptoms of a hereditary disease, Padget's syndrome, not known until the 19th century. It seems implausible that all of those apparently unrelated details of the story would have stayed together for the three hundred years between the events and the writing down of the saga, unless they had been combined into a single narrative composed shortly after Egil's death and transmitted thereafter as oral literature.

What about Islamic law? It purports to be based on two sources, both reflecting divine revelation—the Koran and the Hadith. The latter are traditions of what Mohammed and his companions did and said. The theory is that, since Mohammed was divinely inspired, his practice provides evidence of how God wishes believers to act—including men making and enforcing legal rules. 

Since the traditions can be used as evidence for and against various interpretations of the law, there was an obvious incentive to fabricate suitable ones, a point recognized by Islamic legal scholars. There was thus an extensive scholarly project in the early centuries to separate out the reliable traditions from the unreliable ones, based in part on each tradition's isnad, the account of who heard it, whom he told it to, and the series of oral links through which it was transmitted until it was eventually written down.

Some recent scholars, primarily western, have challenged this traditional account, arguing that all or almost all of the traditions are bogus, invented long after Mohammed's death in the course of disputes over alternative versions of the law, versions themselves based largely on non-religious sources—pre-Islamic Arab law, the legal traditions of the conquered provinces, and the administrative rules created by the conquerors in the early years. Their arguments depend in part on analysis of the supposed chains of transmission, in part on evidence that many of the supposedly genuine hadith deal with issues that could not have arisen in the early period from which they claim to date. Curious readers can find an entertaining discussion of one small part of the controversy in "The Truth About Cats and Dogs," an essay by Vikør.

By now the relation between the two controversies should be clear. Our understanding of the legal system of saga period Iceland depends, in part, on how willing we are to believe in the oral transmission of prose texts, the original versions of the sagas, over a period of centuries. Our understanding of the history of Islamic law depends, in part, on how willing we are to believe in the oral transmission of prose texts, the traditions of what Mohammed and his companions said and did, over a period of centuries. In each case, the alternative interpretation of the evidence, implying an alternative view of the history of the relevant legal system, is that the texts were actually invented by the people who wrote them down.

Chavez, Assad, and the American Left

My guess is that Americans who consider themselves left wing tend to approve of Hugo Chavez, as they have, traditionally, tended to approve of Fidel Castro. I would also guess that, like most other people, they tend to disapprove of Bashar Al-Assad and his violent suppression of opposition in Syria.

Chavez, however, is one of the few national leaders to support Assad. Assuming my guesses are correct, how do American (or, for that matter, European) leftists deal with the situation? One might view it, on a much smaller scale, as analogous to the problems faced by communists and those sympathetic to communism at the time of the Hitler/Stalin pact.

Colliding Seminars

This semester I am teaching two seminars, one on Legal Issues of the 21st Century and one on Legal Systems Very Different From Ours. Two days ago they collided.

The topic for the day in the legal issues seminar was human reproductive technology; one of the issues that came up was gender ambiguity. It is convenient to think of all human beings as either male or female, and it is a pretty good approximation, but no more than pretty good, for reasons some of which have only been discovered recently. Some humans are neither XX nor XY and so, genetically speaking, neither male nor female. Some humans are genotypically male but phenotypically female, or vice versa, presumably due to something going wrong in utero. Some humans are, judging by their own accounts, genetically and morphologically of one gender but psychologically of the other—and modern medicine makes it possible for them to surgically correct the error, although imperfectly. Finally, it has been known since antiquity that some humans are hermaphrodites (the politically correct term seems now to be "intersex," although it  covers a wider range of conditions), possessing both male and female sexual organs. 

All of which raise potentially interesting problems for legal rules, norms, cultural patterns that are based on the simple binary categories—a subject covered in an interesting paper by one of my students a few years back. So far as I know—readers are welcome to correct me if I am mistaken—these issues were ignored in traditional Anglo-American law. 

They were and are, however, treated in some detail in traditional Jewish law—one of the systems covered in my other seminar. That legal system recognized two categories other than male and female. One consisted of hermaphrodites. The other was labelled "tumtum" and seems to have been a condition in which the genitals were somehow concealed—at least, the discussions assumed the possibility that surgery might reveal whether a tumtum was actually male or female.

Under Jewish law, the religious obligations of men and women are different. That raised an obvious question—what were the obligations of someone in one of the other categories? One answer given by some sages was that, since such a person might be either male or female, he/she/it was obliged to do anything required by religious law of either a male or a female—just to play safe. Others apparently felt that ambiguous cases should be considered male. Doing a little last minute research to see how the ancient law dealt with the modern problem, I came across a web page discussing various opinions, ancient and modern, on the application of Jewish law to individuals of ambiguous gender—pretty obviously written by and for people to whom it was still a live issue in a living legal system.

A Better Way of Learning

One problem with the usual approach to education at all levels is that it mostly consists of having someone learn something not because he at the moment has any need to know it but because someone else told him to learn it, possibly on the grounds that the knowledge or skill will be useful at some time in the future. It is much easier to get someone to actually learn something if it is of immediate use to him. The best way of learning a computer language, in my view, is not to start by working your way through the manual but to start with a program you want to write. You then have an immediate incentive to learn what you need to write it, and immediate feedback as to whether you have succeeded.

That approach works in a wide variety of other contexts. When my home schooled son was about eleven or twelve, he was running a weekly D&D game for a group of other home schooled kids. It was good training in responsibility. Each week, when the other players showed up, he had to have already done all of the work of preparing that week's session—otherwise the game, his project, would fail. Each week he did. It was, I think, better training than if he had been a student with homework due on a regular schedule. The homework would have been someone else's requirement, with no justification other than someone else's orders. This was his project—and it was obvious what he had to do to make it work.

Suppose you are a comfortably well off parent. Almost everything your child wants—toys, books, games—is available to be bought at what is, in terms of your income, a trivial cost. That makes it hard to do a believable job of teaching your child the importance of saving, of deciding which things he really wants and which he can do without, skills that he will need, as an adult, to function in a world of limited resources.

If your child plays World of Warcraft, he will learn the relevant lesson with no need for you to impose arbitrary limits. He will have a limited amount of gold and a considerable variety of things he would like to spend it on. Increasing that amount will require him to spend time doing daily quests,  figuring out what he can craft and sell at a profit and crafting and selling it, or perhaps, if he is a mage, running a magical taxi service teleporting other characters hither and yon for pay. Whatever his effort, he will probably not end up with enough gold to buy everything he wants. Here again, the lesson works because it is, in its own odd way, real. These are the things he has to do in order to achieve the objectives he has himself chosen.

I was reminded of the same point today in a very different context. At lunch there was a talk on the Northern California Innocence Project, which is run out of, and largely staffed by, the law school I teach at. The purpose of the project is to identify people who have been convicted of crimes they did not commit and get their verdicts reversed and them released. While the project involves some lawyers and at least one faculty member, a lot of the work is done by law school students. Seen from one side, the purpose is to get innocents out of prison. Seen from the other, it is to help educate our students. 

Considered as education, it is a strikingly successful example of the  approach I have been discussing. The students are learning legal skills, how to interview witnesses, convince judges, prosecutors, juries, file the right paperwork, make the right legal arguments. They are learning those skills not because someone else has told them they will need them five years from now to do the work someone then will pay them to do, but because they need the skills now to do something they very  much want to do, to right a wrong, to rescue someone unjustly imprisoned. 

Pretty clearly, it works.

The Boy Who Cried Wolf

A number of political commenters have compared the current Republican contestants unfavorably with Barry Goldwater. The current crop, we are told, are religious nutcases, or possibly pretending to be. Goldwater, on the other hand, was an intelligent and reasonable man, even if not on the right side of every issue.

I have been reading my parents' autobiography, and recently got to the Goldwater campaign. Their description fits my memory. What we were being told then—by people almost none of whom could have done a competent job of explaining Goldwater's positions or the arguments for them—was that he was a dangerous madman. There was even a piece by some large number of psychiatrists, none of whom had ever examined the candidate, explaining how crazy he was. And the TV ad with the little girl, the countdown, and the mushroom cloud.

A while back I read an article attacking Bjorn Lomborg, an articulate  critic of much of the current environmental orthodoxy. It included a respectful reference to the late Julian Simon. Simon,  criticizing the population  orthodoxy, was making reasonable arguments, some of which turned out to be right. Lomborg, on the other hand ...  .

I remember that fight too—I contributed a chapter on the concept of optimal population to one of Julian Simon's books. Back when he was the front line of opposition to the then current orthodoxy, he got the same treatment Lomborg got a decade or two later.

I am not competent to judge the  climate science behind global warming, but I am suspicious of orthodoxies pushed relentlessly in the popular media, orthodoxies that claim that everyone competent agrees on an urgent problem which requires drastic action immediately if not sooner. I remember when we were being assured that it was simply a scientific fact that overpopulation was the cause of poverty and a near term threat to our own well being, if not survival. Also when we were assured that the only way to get the poor countries of the world up to our level was central planning, if possible supported by generous foreign aid.

When I see news headlines about global warming having shrunk horses to the size of cats, along with a picture comparing a cat sized horse to a modern Morgan—you have to read down a bit to discover that the ancestral horses shrank to the size of cats from the size of dogs, from 12 pounds to 8 1/2 pounds, and spent tens of thousands of years doing it—I suspect that what I am seeing is driven at least as much by what people want other people to believe as by the evidence for believing it.

Of course, going back to the beginning of this post, it's entirely possible that some of the Republican candidates are religious nutcases. With the possible exception of Ron Paul, none of them strikes me as someone I would be comfortable with as president. 

But after being told, time after time, that everyone competent to judge agrees with whatever views are currently fashionable with the academic and media elite, reasonable people stop believing it. 

Which brings me back to the title of this post.