Thursday, July 10, 2014

The Third Edition of the Machinery of Freedom is Now Available

As a kindle on Amazon.

It is not currently available in hardcopy. I am interested in comments from people as to whether they would want it to be. The kindle is up at $2.99. If I self-publish a hardcopy with CreateSpace it would be substantially more than that, and if I go with a commercial publisher more still. 

I am also interested in comments by people who read it and spot mistakes. One of the advantages of an eBook is that it's easy to make minor changes.

Tuesday, July 08, 2014

What We Could Learn From Dan Kahan. And Perhaps Shouldn't

I have commented in earlier posts on Dan Kahan's research about why we believe what we do. The basic conclusion is that, in the case of beliefs linked to group identity, individuals choose what to believe not on the basis of the evidence but on the basis of what beliefs fit their group identity. For most of us, as Dan points out, that is rational behavior. My beliefs about evolution or global warming have  little effect on the world at large but could have a large effect on how well I get along with the people who matter to me.

There is no reason to assume that the pattern I have just described only applies to other people. One possible conclusion is that I ought to look for beliefs that it is very much in my interest to hold and think about how good my reasons are for holding them.

One of the first candidates that occurs to me is my belief that minimum wage laws have bad effects, that they make it harder for unskilled workers to get jobs. That is a belief widely held among economists, especially economists generally in favor of free markets. Academic economists are part of an academic world where most people are politically liberal, hence inclined to support minimum wage laws. That makes the fact that economists are inclined to oppose them an important marker for group identity. And I have evidence of the cost to an economist of rejecting it from an interview with David Card, coauthor of a widely cited study that failed to find the expected effect. By his account, getting what was, from the standpoint of his professional peers, the wrong answer cost him a lot of friends.

That is a reason to think that my view on the subject might be mistaken but I cannot think of any good arguments against it, so I will rapidly pass on from my possible false beliefs to other people's. Dan Kahan's, for example.

Dan is a professor at Yale law school. My guess is that if he pointed out that there is no good reason to expect the distribution of intellectual abilities to be the same for men as for women, hence no good reason to interpret unequal outcomes as evidence of discrimination, he would suffer significant social costs. If he made the same point in the context of racial differences, the costs would be more than merely significant. Perhaps he should think about those questions, examine the arguments and evidence, and revise his beliefs accordingly.

Or perhaps not. His explanation for what he observed, after all, was that it was the result of rational behavior. Believing things merely because the evidence supports them may sound like an admirable policy, but it could prove to be a very expensive one.


Why Improving Things Is Hard

Someone who studies the effects of different diets comes up with evidence that consuming more salt causes high blood pressure and associated medical risks and concludes that people should eat less of it. Another researcher repeats the study looking at mortality from all causes and finds that people who eat more than the average amount of salt are no more likely to die early than people who do not.

Arguably you not only should not be surprised at the result, you should expect it. We have, after all, been "as if designed" by evolution for reproductive success. Dying, whether from high blood pressure or some other cause, makes it difficult to either help rear your existing children or produce more. Our bodies have built into them a sophisticated chemical factory for converting what we eat into what our body requires; reducing the amount of salt absorbed and excreting the excess should not be beyond its capabilities. If the body instead  absorbs all the salt consumed, that suggests that the disadvantages of higher blood pressure are on average balanced by other advantages.

That is one example of a more general point, suggested by my rather vague memories of what I have read about the effects of salt consumption and a comment someone made on an earlier post. For another, and this time entirely imaginary, example of the same point, suppose you discover that increasing the size of your car's tires improves its gas mileage. Before concluding that bigger tires are a good idea, it would be prudent to look at other consequences of the change—because you will probably discover that some of them are negative.

The logic is the same as in my previous example, although this time the design is by engineers rather than by evolution. People who design automobiles would like them to use less gas. If bigger wheels achieved that objective and had no disadvantages, someone in the past century would have discovered the fact. The current size of wheels is not an accident. It is the best solution engineers could come up with to the problem of optimal design.

The argument does not apply to everything; there is no reason to assume that either the climate or the population of the earth is optimal. But it does apply to anything that has already been optimized for some purpose, whether by human design or some natural mechanism. Any change from the present design that produces a benefit probably also produces a cost. That is why it is not already in the design.

Of course, even if something has been optimized, it may have been optimized for a purpose other than yours. Evolution designs organisms, including me, to do the best possible job of passing their genes down to later generations. That is its objective but not mine. Birth control is one of the ways in which humans subvert the objectives of the genes in order to better achieve their own objectives. 

For another example, consider trade barriers such as tariffs. There are good economic arguments to show that we would be better off if we went to complete free trade. That seems puzzling—if we would be, why don't we?

The answer is provided by public choice theory, the branch of economics that deals with the workings of the political market. A tariff makes the inhabitants of the country that imposes it worse off but the politicians who pass the tariff better off, since it benefits a concentrated interest group at the cost of dispersed interest groups. More concentrated interest groups are better able to pay politicians to do things for them.Trade policy is optimized, but for the wrong objective.

Another exception to the general rule occurs where optimization is slow and constraints have recently changed. Through most of the history of our species it made sense to get fat if you could in order to increase your odds of surviving the next famine. Now that famines are vanishingly rare, the same hardwired tastes produce less optimal behavior. Similarly, if gas prices have recently gone up a lot, existing car designs may weight fuel efficiency less heavily than  they now should.

Improving things is not always impossible. But it is often harder than it seems.

Friday, June 27, 2014

Another Good Article by Dan Kahan

The source of the public conflict over climate change is not too little rationality but in a sense too much. Ordinary members of the public are too good at extracting from information the significance it has in their everyday lives. What an ordinary person does—as consumer, voter, or participant in public discussions—is too inconsequential to affect either the climate or climate-change policymaking. Accordingly, if her actions in one of those capacities reflects a misunderstanding of the basic facts on global warming, neither she nor anyone she cares about will face any greater risk. But because positions on climate change have become such a readily identifiable indicator of ones’ cultural commitments, adopting a stance toward climate change that deviates from the one that prevails among her closest associates could have devastating consequences, psychic and material. Thus, it is perfectly rational—perfectly in line with using information appropriately to achieve an important personal end—for that individual to attend to information on in a manner that more reliably connects her beliefs about climate change to the ones that predominate among her peers than to the best available scientific evidence.
His empirical claim is that disbelief in global warming, or in evolution, is not evidence of scientific ignorance. If you separate groups on roughly a left/right basis, belief in warming increases with increasing scientific intelligence (measured in other ways) in the group predisposed to believe in it (left), decreases with increasing scientific intelligence in the group predisposed not to believe in it (right). Similarly with evolution if you divide the groups into more or less religious. His explanation ...:
If that person happens to enjoy greater proficiency in the skills and dispositions necessary to make sense of such evidence, then she can simply use those capacities to do an even better job at forming identity-protective beliefs.
The article is too long and starts with an irrelevant analogy to observer effects in quantum mechanics, but it has lots of interesting stuff in it. Among other things, if you test people to see how much they understand about the theory of evolution, those who believe in it do no better than those who don't. Similarly for global warming.


Monday, June 23, 2014

Interesting Post About the Climate Argument

I came across a recent piece discussing evidence about beliefs on climate issues. It finds  that Democrats mostly believe temperatures are warming due to human action and something must be done about it, Republicans mostly don't, but that the difference is not due to differing perceptions about what climate scientists believe. If the question is not what is true but what most climate scientists believe, Republicans and Democrats give roughly similar answers—correct in some cases, incorrect in others.

The author's conclusion is that the debate has become a status conflict, with each side taking the position that it is wise and good, the other side the opposite. One implication he draws is that the campaign to persuade people that 97% of climate scientists agree is based on the mistaken assumption that the reason people are not persuaded is that they don't know what climate scientists believe.

It struck me that his description fits my observations of the online debate. Most participants appear confident that their side is right, the other side stupid or evil. Most of the posts and comments are attempts by one side to put down the other. Substantive arguments occasionally appear, but they are largely cut and paste from popular web sites on the side of whoever is posting them.

I should add that I do not think it is clear what climate scientists believe. As best I can tell by my involvement in the argument, most such scientists think global temperature has been trending up and humans are at least partly responsible, many, perhaps a majority, think humans are mainly responsible. I have seen no evidence of what percentage take the next two steps, the conclusion that if nothing is done the results will be terrible and the further conclusion that there is something that can be done that is worth doing. But those steps are essential for the policy argument that one side of the dispute is pushing and the other side opposing.

As of 5:50 EST 6/23/14 the piece described in this post appears to have vanished. I have not yet figured out why or where, if anywhere, I can find it again.

After an exchange of emails with the author, who turned out to be someone I knew from my time at U of C Law school, the link is now fixed.

Friday, June 20, 2014

The Purpose of Commencement Addresses

I don't usually make posts that are links to webcomics, but this one is both good economics and good commentary.

I deduce from further research that the strip in question is aimed at readers with a background in physics and economics and side interests in philosophy and probability theory. Funny that.

Thursday, June 19, 2014

Is the Ocean Still Warming?

The latest data seem to show a very considerable slowdown in ocean warming, starting a few years after the slowdown in atmospheric warming.

That raises an obvious puzzle. As I understand the situation—readers are welcome to correct me if I am wrong—there are satellite measurements of incoming and outgoing radiant energy, and they show a substantial net inflow. If atmosphere, surface, and ocean are all warming much more slowly than they were twenty years ago, where is that energy going?

The two obvious alternatives are that we are missing something, that warming is happening somewhere we cannot readily measure it such as the deep ocean, or that there is something wrong with the measurements that show a net inflow. I do not know enough to offer an educated guess as to which is the case and no other alternatives occur to me.