50 000 comments

Some time in the past few days, my WordPress dashboard recorded its 50 000-th comment. I meant to watch out for it and note the lucky commenter, but I’ve been travelling and missed it. These comments span the period since the beginning of 2004 – I lost thousands of comments in the Great Database Disaster of 2003, and there were lots more in an early commenting system called Haloscan that I never managed to transfer.

Comments are a crucial element of a blog, and I’d like to thank both regular and occasional commenters for their contributions and for the fact that, most of the time, discussion here is sufficiently civilised and constructive to advance our understanding of the issues. If you’ve thought about commenting, but not got around here, this post would be a great opportunity

On the other hand there’s the spammers who make running comments much harder than it should be. I’ve only been running Akismet for six months or so, and its already picked up more than the 50 000 genuine comments accumulated over three years.

Exxon joins the real world

For the last few years, Exxon Mobil has been the biggest single source of support for global warming denialism, and has also exercised a lot of influence on the Bush Administration in its do-nothing stance. For a long while, Exxon was able to act through front groups like the Global Climate Coalition, but the corporation has been increasingly isolated and its activities have been exposed to public scrutiny, most notably with the open letter from the Royal Society last year.

Now Exxon has changed its position, recognising the inevitability of some sort of controls on CO2 emissions, and lobbying for a broad approach that will be relatively favourable to businesses like Exxon, rather than one tightly focused on the energy industry. At this point, an association with shills for denialism like the Competitive Enterprise Institute is counterproductive as well as being embarrassing, so they’ve been cut adrift (along with half a dozen others not yet named).

In other news, Stern has responded to critics of his review in a recently published postscript. There’s also a Technical Annex with a sensitivity analysis, something that both critics and those (like myself) with a generally favorable view should welcome.

Weekend reflections

Weekend Reflections is on again. Please comment on any topic of interest (civilised discussion and no coarse language, please). Feel free to put in contributions more lengthy than for the Monday Message Board or standard comments.

Pro-war bias (crossposted at CT)

The fact that people are so willing to support war is a puzzle that requires an explanation. After all, war is a negative-sum activity, so war between rational parties doesn’t make sense – there’s always a potential settlement that would leave both sides better off*. And empirically, it’s usually the case that both sides end up worse off relative to both the status quo ante or to a possible peace settlement they could have secured at a point well before the end of the war. Even the observation that rulers start wars and ordinary people bear the costs doesn’t help much – leaders who start losing wars usually lose their jobs and sometimes more, while winning a war is by no means a guarantee of continued political success (ask Bush I) All of this suggests that looking for rational explanations of war, as in the ‘realist’ tradition (scare quotes indicate that this self-ascribed title has little to with a reality-based focus on the real world) is not a good starting point.

So it makes sense to look at irrational sources of support for war. In this pice in Foreign Policy Daniel Kahneman (winner of the economics Nobel a couple of years back) and Jonathan Renshon start looking at some well-known cognitive biases and find that they tend systematically to favor hawkish rather than dovish behavior. The most important, in the context of today’s news is “double or nothing” bias, which is well-known in studies of choice under uncertainty as risk-seeking in the domain of losses (something first observed by Kahneman and Amos Tversky in their classic paper on prospect theory).

The basic point is that people tend to cast problems like whether to continue a war that is going badly in win-lose terms and to be prepared to accept a high probability of greater losses in return for a small probability of winning or breaking even. So we get the Big Push, the Surge, the last throw of the dice and so on.

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Yet more on Stern (quicklinks and brief summaries)

Megan McArdle has a generally sensible post on the main issues, though I disagree on some points as I note in comments, and I still don’t see that this has any bearing on the rights and wrongs of abortion (except relative to the obviously silly position that we are morally obliged to have as many children as possible).

Arnold Kling makes it clear that he doesn’t understand the mathematics of discounting. The first comment, by Michael Sullivan gets it right, but there’s no response or correction so far from Kling. Kling has now corrected his post.

James Annan links to this piece by Paul Baer,. Baer puts the view (with which I have some sympathy) that Stern underestimates the costs of the melting of the Arctic ice cap, which could happen even with stabilisation at 550ppm.

I definitely need to come back to the issue of the costs of global warming. My general view is that, while Stern’s choice of discount rate is at the low end, the Review badly underestimates the social cost of the damage to natural ecosystems that will inevitably arise from global warming.


Akismet has been marking most incoming comments as spam. I’ve rescued a bunch of them, but no doubt not all. Apologies to people whose comments have been lost.

With luck, manual correction will fix the problem. If not, I may have to move to some sort of active verification scheme, a step I’ve always rejected.

If you post a comment and it doesn’t appear, please email me.

Refugees again

Pamela Hartman of LA has another piece (over the fold) on the experiences of Iraqi refugees and the virtual impossibility of gaining refugee status in the US. She asks if anyone has any information on possibilities for refugees seeking to come to Australia. If anyone can help, they could get in touch with her at Pamela Hartman .

It’s obvious that neither the US nor Australian governments has any plan to do anything for the refugees (now numbering up to a million outside Iraq and an equal or larger number displaced internally)) their war has created. But at the very least, they are surely obliged to offer asylum to those whose lives are in great danger because they were unwise or desperate enough to work with the Coalition forces. Leaving these people in the lurch (as was done with the Shiites after the last war) will ensure that even those who were willing to be our friends will end up as our enemies
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Non sequitur (Crossposted at CT)

In the Monday Message Board, Michael Greinecker points to a truly strange response to arguments for a zero rate of social time preference.

Crucial quote

I found myself becoming very curious whether economists who support Sir Nicholas’s social discount rate of zero, such as econ bloggers John Quiggin and Brad DeLong, identify themselves as pro-choice or pro-life, and whether they had considered the Stern Report from this angle.

My response has been anticipated by a commenter who observes

Strange as it may seem to Economist writers, there are phenomena in the world that aren’t particularly illuminated by applying economic concepts. Attitudes towards abortion have nothing at all to do with discounting rates.

Others in the comments thread spell this out.

One odd feature of the Economist blog is that contributions are anonymous. I know that Megan McArdle (aka Jane Galt) has something to with the site. While I’m used to pseudonymous commenters, most economics bloggers are (as Matt Yglesias puts it) proudly eponymous, or at least easily identified, and I find this a more satisfactory mode for arguing about issues like the Stern Review, though can’t exactly say why.

Discounting and impatience with overlapping generations (Crossposted at CT)

During the discussion of discounting and the Stern Review, I got an email raising a point that I had already been worrying about. In discussing costs and benefits in 2100, I and others routinely refer to future generations, and in a sense that’s right, since the people involved in the discussion won’t be around then. But, children alive now have a reasonable chance of living to 2100 – quite a good chance if life expectancy keeps rising. Economists often deal with this kind of thing by modelling a series of overlapping generations, but I haven’t seen much discussion of this in relation to benefit-cost analysis, though no doubt it’s in the literature somewhere.

I finally got around to thinking about this, and in particular the following question. Suppose we accept an ethical framework in which everyone now alive matters equally. Suppose also that as individuals we have a consistently positive rate of time preference, preferring to have higher utility now at the expense of less in the future, that is, more when we are young and less when we are old (this isn’t obvious by the way, but I’m assuming it for the sake of argument) . What is the appropriate pure rate of time preference for society as a whole?

My preliminary answer, somewhat surprisingly to me, is “Zero”. I’ll set out the outline of the formal argument over the fold, but the simple summary has two parts. First, since generations overlap, if, at all times, we treat all people now alive as equal then we must treat all people now and in the future as equal. Given this equality, positive individual rates of time preference translate not into a social preference for the present over the future but into a social policy that consistently puts more weight on the welfare of people when they are young than when they are old.
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