Bryan Caplan  

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Clark and I are moving toward agreement on the implications of the Malthusian model, but I'm still not satisfied. He writes:

Caplan replaces my figure 2.1 with one where disease and harvest failures cause the technology schedule to move down but leave the death rate unchanged. But even if he is correct that bad stuff killed people but also affected production possibilities, then the new picture should still involve a shift in the death schedule.
Does it? It depends. If bad stuff kills people solely by reducing income, then the Technology Schedule should shift, and the Death Schedule should stay fixed. If bad stuff kills people directly, with no indirect effect on income, then the Technology Schedule should stay fixed, and the Death Schedule should go up. If bad stuff kills both directly and indirectly, then both should shift (as I explained in the post script of "Malthus on Stilts").

I'll defer to Clark historical expertise when he describes the Plague as a pure shift in the Death Schedule. But at the other extreme, harvest failures, which Clark praises in identical terms, are basically pure shifts in the Technology Schedule.

Most of the other bad stuff that Clark praises on Malthusian grounds is closer to a harvest failure than a Plague. Indeed, as I mentioned, noted economic historian Robert Fogel emphasizes the economic drain of chronic bad health on the pre-modern economy. Is Fogel wrong, Greg?

Clark goes on to tell us:

The normative statement: - “England was lucky to have been struck by the plague” is more debatable. But let me make that case. 1.5 million people died prematurely in 1349. In return 6 generations got to live very well with little further excess deaths. And then 1.5 million people got to live longer as the plague weakened its grip in the 16th century, and the population returned to its earlier level. The unlucky generation of 1349 was counterbalanced by the lucky generations of 1540-1620.

God smiled on the English when he delivered the plague!

Somehow I doubt that the grief felt by plague survivors at the loss of a third of their families compares to the satisfaction generated by the rising life expectancy of the generations of 1540-1620. But even leaving this aside, I'm puzzled. If we're doing a utilitarian calculus, why isn't it bad to have six generations of lower population?

Question for Clark: What, in your view, is the socially optimal fraction of the population for the plague to kill? If 25% death is a gift of God, why not 50%? 90%?

Update: I posted a follow-up from Clark in the comments.


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COMMENTS (13 to date)
Scott Scheule writes:

Does he ever say that six generations of lower population isn't a bad thing?

My guess is he does not. Clark's position simply seems to be that the increases in utility of the plague (consisting of longer lifespans for future generations) outweighs the decreases in utility of the plague (consisting of lower population and the initial deaths).

General Specific writes:

Bryan Caplan wrote: "I'll defer to Clark historical expertise when he describes the Plague as a pure shift in the Death Schedule. But at the other extreme, harvest failures, which Clark praises in identical terms, are basically pure shifts in the Technology Schedule."

It doesn't seem as if this statement has ever been motivated or substantiated by you. After a harvest failure, the young, weak, and sick are more likely to die. The death rate goes up amongst this segment of the population. In addition, a harvest failure is likely to operate non-uniformily. Some will outright starve, others will either have sufficient harvest to get by or stores or other means to get by. Populations will then shift to make up for the heavy losses in certain regions.

Even a harvest failure seems like a shift in the death schedule to me.

Can you motivate otherwise?

Tom Myers writes:

Imagine that society A has uniform harvests: they never fail, so population rises after X generations to the point of Malthusian misery. Society B has a crop-failure every twenty years, so that a quarter of the population die in the following winter, and the remainder have a pretty bad spring until the first vegetables come out, but then they're better off in per-capita income terms until the next failure. Both have long-run stable (or slightly-growing) populations; comparable life expectancies, comparable reproductive success, but a dying A looks back at a hungrier lifetime than a dying B. I think Clark would say that on the average, Bs are "better off" than As. I'm not sure, but I think it's a defensible point of view.

Ben writes:

[quote]Question for Clark: What, in your view, is the socially optimal fraction of the population for the plague to kill? If 25% death is a gift of God, why not 50%? 90%?[/quote]

Isn't the answer obviously marginal cost = marginal revenue? At equilibrium, you have MC = MB, so the next person will survive just so long as his existence produces enough for him not to die. The person after him starves or causes someone else to.

At MC = MR, an additional person should necessarily bring down the average real income. So if a plague took out enough people to make MC = MR, you'd expect to maximize income. It will move towards equilibrium because it's essentially a free market for having kids. Of course, I don't know if the percentage who would need to die to reach MC = MR has been empirically established for that era or any other.

Ben writes:
Question for Clark: What, in your view, is the socially optimal fraction of the population for the plague to kill? If 25% death is a gift of God, why not 50%? 90%?

Isn't the answer obviously marginal cost = marginal revenue? At equilibrium, you have MC = MB, so the next person will survive just so long as his existence produces enough for him not to die. The person after him starves or causes someone else to.

At MC = MR, an additional person should necessarily bring down the average real income, as should one person fewer. So if a plague took out enough people to make MC = MR, you'd expect to maximize income. It will move towards equilibrium because it's essentially a free market for having kids. Of course, I don't know if the percentage who would need to die to reach MC = MR has been empirically established for that era or any other.

Matt writes:

I didn't see how Malthusian theory predicts two different solutions to population level in terms of technology, which is what Clark is implying. Malthus seems, having not read him, to imply equilibrium solutions, "after all things settle" is what I hear economists say.

Clark is simply saying that births equal deaths after we settle out the effect of periodic plagues.

Bryan Caplan writes:

Here is another reply from Greg Clark. All that follows is from him.

More response from Clark
(1) Harvest Failures – I think Arnold Kling identified well the reasons why I put harvest failures in the “good” column for the Malthusian Era. But I also understand Bryan Caplan’s objection to this in terms of the model. So let me try and clarify.
Suppose you had to choose between two economies. In one through government policies or the nature of the climate the supply of food is the same each year. In the other every 20 years there is a bad harvest that kills 10% of the population. The average food production is the same. We can thus think of the second economy as having the same average technology schedule, but a higher death rate schedule.
My thinking was that you are better off on average in the one with the periodic disaster. Life expectancy will be roughly the same (life expectancy in the pre-industrial world is just the inverse of the birth rate). And because there is an extra source of mortality, on average deaths from economic causes have to fall.
So pre-industrial governments like those in China that stored grain and distributed them to the poor in years of harvest failure reduced, rather than increased, average material welfare.

(2) Technological Advance – Bryan is absolutely correct that technological advance improves human welfare, at least temporarily, in the Malthusian era. But I do not say in FTA that it is bad – I say instead that the rate of advance was so slow before 1800 that it had negligible effects on material welfare.

(3) Population Size – Bryan is also right in saying that population size may have a value also, as well as material welfare. And indeed the book accepts that one of the things bringing about the Industrial Revolution was the much greater population of the world in 1800 than in 100,000 BC.
But in practice the weight we give to population as opposed to income per person in the modern world is very small, particularly when incomes are very close to physical subsistence. We do not have newspaper headlines warning “Uganda achieves record 3.5% annual population growth rate in 2007 – can the US meet this challenge?”

(4) Writing Style – In his introductory post on the book Bryan notes disapprovingly that Clark “delights in counterintuitive claims”, “scoffs” at the importance of institutions/policies.
I confess to the crime. I tried to write a book that would both be sound in terms of analysis and evidence (there is a great deal of evidence in the book for various claims – there is a reason this book took 12 years to complete), but that would also be playful, surprising, and ironic.
I know the book does not read like the standard economics monograph, or like an Intermediate Micro text. But since when did the economics profession become such a temple that we cannot laugh a little at some of our own sacred doctrines, which are maintained more by hope and faith than by any hard evidence? It is ironic that even after the Scientific Revolution of the 17th century the correct way to analyze the economies of people is the same way we would analyze hyena or wildebeest society.

eric writes:

Hmmm...maybe there was a method to the madness of Mao and those mass Mayan sacrifices! This is a great case for genocide against, I dunno, rich people, which, to be meaningful would have to go down to those making more than $100k/year or with $1mm in net wealth:

1) lowers inequality
2) raises wages and productivity
3) lowers stress on infrastructure, natural resources, our 'carbon footprint'

Freshly killed bodies need no longer be wasted in mass graves, but can used as protein for people and livestock, or burned in sustainable energy solutions. The key is good top-down support and direction.

Seems like a small price to pay every century or two.

eric writes:

forgot to add: to make this eugenic, kill only the stupid rich people

Bruce G Charlton writes:

These comments from GC are pure gold!

I'd have to say that I regard FtA as a work of genius.

Time will tell whether I am correct. But just now the book seems first rate - and the deftness, concision and ironic wit are a vital part of that.

John S Bolton writes:

It's interesting to see the false dilemma and attempted smearing here,all confirming that there is still no rational argument for releasing the failed populations on the successful ones. It is still reasonable and we still owe loyalty to fellow citizens over against foreigners who would raise the level of aggression, moving here. We still evaluate officials by whether they can raise per capita standards without increasing the level of aggression, in the jurisdiction for which the decision is to be made. If Caplan's false dilemmas were actually plausible, it would seem that we would be praising a politician who found out how to lower our per capita incomes, but also found a way to double an African population many times larger. The people rightly do not honor disloyalism and traitorous schemes, and will not give power to those who want to be the vectors of universalized third world squalor.

John S Bolton writes:

It's a lot like Julian Simon's false dilemma of saying that valuing per capita income would mean killing off the poor. Those are not known to be our only choices; the Simonesque would have to prove that those are our alternatives and that we are so constrained, not just smear the good and responsible. Does free overflow of fast-expanding failed populations into successful societies not threaten all of humanity, even the poorest with mass death by infectious disease if progress stalls and rolls back due to faltering quality of population leaving no margin for 'extras' like research? The more-people-is-always-better believers must prove this before asking the responsible to sign on to an experiment of such huge change, with no indications that it would succeed.

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