A Case of Posthumous Conscription

A recent Forbes article is headlined "What Would Milton Friedman Do About Climate Change? Tax Carbon." It reports on a forum at the University of Chicago at which several economists, including Michael Greenstone, described as the "Milton Friedman Professor of Economics at the University of Chicago," argued that Friedman would have supported a carbon tax. The evidence for that claim was a 1979 clip from the Phil Donahue show where Milton Friedman argued that if the government is going to do something about emissions, they should use an effluent tax rather than direct regulation. He does not actually say that government should do something about emissions, only that there is a case for doing so and, if it is done, the best way to do it is by a tax on emissions.

To get from there to the conclusion that he would have favored a carbon tax requires at least one further step, a reason to think that he would have believed that global warming due to CO2 emissions produced net negative externalities large enough to justify doing something about them. The problem with that claim is that warming can be expected to produce both negative externalities such as sea level rise and hotter summers and positive ones such as longer growing seasons and milder winters. The effects will be spread out over a long and uncertain future, making their size difficult to estimate. My own conclusion, defended in past posts here (one example), is that the uncertainties are large enough so that one cannot sign the sum, cannot say whether the net effect will be positive or negative.

I do not know if my father would have agreed but I have at least a little evidence on the subject, more than offered in the Forbes article. The same issue arose in the earlier controversy over population. Just as it is now routinely assumed that warming is bad, it was then routinely assumed that population increase was bad. Forty years ago I wrote a piece on the subject for the Population Council in which I attempted to estimate the  externalities associated with population. I concluded that they were too uncertain for me to tell whether the net effect was good or bad. My father read the piece and commented on it. If he had disagreed he would have said so, and he did not. It is possible that he would have felt differently in the case of climate change, but I can see no reason to expect it.

The article quotes professor Greenstone on the uncertainty:

Estimating the cost is tricky, Greenstone said, but scientists and economists have models for projecting the cost of each added ton of carbon on agricultural losses, mortality, sea-level rise, storm surge, and other climate effects.

It’s a complicated task but I think the best evidence suggests that it’s probably around $40 a ton,” he said. The U.S. government has projected the cost of carbon emissions at $37 per ton.

Current estimates of climate sensitivity, the effect on temperature of an increase in CO2, vary by more than a factor of two. One would expect the size of the externality due to an additional ton of CO2 to increase with the temperature increase. A further uncertainty, reflected in the various scenarios of the IPCC report, is the amount of CO2 that will be emitted over the next century. Lockheed Martin has recently claimed that it will have a working fusion reactor in the near future. I have my doubts that it is true, but if it is, the result should be to reduce CO2 emissions over the course of the next few decades to between half and a quarter of what they would otherwise be. That would sharply reduce warming and thus the cost of additional CO2.

One would expect similar effects from any substantial reduction in the cost of other alternatives to fossil fuels, such as nuclear or solar power, or from a substantial increase in the cost of fossil fuels due to the exhaustion of the more readily accessible sources. Additional uncertainties are associated with the relevant climate science. The IPCC, for example, claimed in its fourth report that warming increased drought, retracted that claim in the fifth report.

Whether or not my view that we cannot sign the externality is correct, I would be very surprised if Professor Greenstone could justify his confidence in the specific number he offered—which happens to be close to the official government estimate. I would be equally surprised if he could offer evidence that Milton Friedman would have taken seriously a government estimate of an uncertain number offered in support of a policy the current administration favored.

Before they died, my parents created a foundation to promote the idea of school choice. One of the terms on which they created it was that the foundation was to end a fixed number of years after the last of the founders died. The reason for that was my father's concern, possibly based on the examples of the Ford and Rockefeller Foundations, that once the founders were no longer around their names would be used in support of policies they themselves would not have supported.

Of all my father's accomplishments, I believe the one he was proudest of was his role in ending military conscription. I do not think he would be happy to be conscripted, posthumously, for someone else's cause.

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P.S. Robert Murphy points at evidence against the claim that my father would have supported a carbon tax. In a 1999 comment to a recently published book, he wrote:

This encyclopedic and even-handed survey of the evidence of global warming is a welcome corrective to the raging hysteria about the alleged dangers of global warming. Moore demonstrates conclusively that global warming is more likely to benefit than to harm the general public.

It is possible that between then and now he would have reversed his view, but I can see no reason to expect it.

Me vs Mankiw on Global Warming

A commenter on a old post of mine about global warming points at a response by Greg Mankiw. Both are from 2007. The issues have not changed since then and, while I responded to Mankiw at length by email, I do not think I ever did so publicly.

Mankiw supports a carbon tax. I argued that while a carbon tax might make sense as the answer to the question "what is the best policy for dealing with negative externalities due to global warming," it did not make sense as the answer to the question "what policy should economists support to deal with global warming" since there was no good reason to believe that, if a carbon tax was implemented, it would take the form economists would recommend. Interested readers should probably read both my post and Mankiw's before going on to my response below, which I have copied from my email correspondence with him.

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It seems to me that you are making the error that was the norm in textbooks and the profession fifty years ago, before public choice theory. You are evaluating proposals for government policy on the basis of what they could do if optimally implemented not on what one can expect them to do given the incentives of the people making the decisions—what used to be referred to as the philosopher king model of government. It makes no more sense than evaluating the market alternative on the assumption that all the decision makers in that case will act to maximize social welfare rather than in their own interest. The question is not whether an optimal carbon tax designed and enforced by wise and benevolent economists would produce net benefits—very likely it would. It's whether passing a carbon tax designed and implemented as we can best expect it to be would produce net benefits.

Two further points with regard to your original blog post:

1. I wasn't making a slippery slope argument. If I had been, I would have argued that carbon taxes would initially be a good thing but would set the precedent for other bad things. In fact I argued that, as implemented, they would probably be a bad thing. As I made explicit in my post, it was a public choice argument—completely ignored in your response. I plan to send in my complaints to the Society for the Protection of Straw Men just as soon as I can find their email address.

2. My argument is  consistent with my father's views. For evidence, take a look at the discussion of professional licensing in Capitalism and Freedom. The argument is not that professional licensing, applied by wise and benevolent officials, could do no good. It is that we can expect, on grounds of both theory and evidence, that professional licensing will usually be controlled by the profession and used to restrict entry and raise prices.

If you look again at the quote from him you link to, he isn't saying that one should recommend policies independent of how one thinks they will be implemented—consider the "in light of what can be done." Professional licensing that isn't captured can't be done, or at least not reliably done, on the evidence. He is saying that one shouldn't refrain from making a proposal merely because you think it can't be passed.

In this context, the implication is that one might argue that a specified form of carbon tax would be a good thing and simultaneously that any carbon tax that could be passed would be a bad thing. I don't believe that is your position.

And, again:

Can you see any hint of evidence that the people proposing cap and trade have made any effort to estimate marginal cost of reduction of carbon dioxide, optimal level of emission, or any of the information necessary for a scheme designed to actually produce net benefits?

Isn't that question relevant to how one can expect a carbon tax (or cap and trade) to be implemented, and isn't that relevant to whether one ought to be in favor of it?