Gregory Clark emailed me the following reply to my criticism and asked me to post it to the blog. I’m happy to oblige. Everything that follows is Clark, not me.

Clark right on Malthus!

Bryan Caplan raises some interesting points in his criticism of my interpretation of the perverse role of sources of higher mortality in raising living standards in the pre-industrial world. But he is wrong for three reasons.

(1) Even if something that caused higher mortality lead to a lower technology schedule, in equilibrium real incomes would still be higher.

(2) Most of the sources of higher mortality in the pre-industrial era had no effect on production processes.

(3) Even taking into account excess deaths from the onset of diseases such as the Plague, they still were blessings!

(1) 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. i.e.

Just looking at this new figure you can see that while the new equilibrium involves more population decline, real wages rise just as much as before. What Caplan has done in redrawing the figure his way is to assume that extra disease has no effect on the death rate at a given material living standard. But this is just to assume away the possibility that the death schedule could change. Now that is a pretty strong assumption, and one demonstrably untrue.

(2) “For Clark’s story to make sense on its own terms, bad stuff would have to directly kill people without affecting the Technology Schedule.” (Caplan).

In fact there was lots of “bad stuff” in the Malthusian era that had just the effect Caplan denies possible.

England, for example, in 1348 was a settled, secure agrarian society with a population of 4.9 million people extracting a modest living from a fixed farmland area of 26 million acres.

Then the Plague arrived. Assuming this was Bubonic Plague, 80% of the afflicted would die within 7 days. The other 20% would fully recover within a few weeks. As the plague marched across England, village by village, by 1350 the population had fallen to 3.4 million. One third of the population was gone within months.

But the economic disruptions of this medical catastrophe were remarkably limited. The harvest of 1349 was successfully brought in. Prices of wheat which were 9 d. a bushel in 1348, were 6 d. a bushel in 1349, and 8.5 d. a bushel in 1350.

Other prices adjusted exactly as if an invisible hand had overnight removed one third of the population. Real wages doubled. Capital goods, such as oxen, fell in price from 12 s. in 1348 to 6 s. by 1350. Labor intensive goods – linen, nails, etc. – became more expensive. Goods such as pepper, imported from southern India, continued to be available at little change in price.

The Plague, in exactly the way Caplan denies is possible, took away people but left the economy entirely intact.

For the next 200 years periodic visits of the Plague kept English population at this new low level. Indeed population by 1450 was down to 2.4 million. But the English enjoyed unparalleled prosperity. The real wages of farm workers in 1450 were not again equaled until World War I, 150 years after the onset of the Industrial Revolution. Life expectancy in 1450 seems to have been little lower than in 1300, since the plague deaths were counterbalanced by lower mortality from other diseases caused by poor material living conditions.

Thus the following factual statement is unequivocably true: – “The Plague raised English material living standards.”

(3) 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!

What about the other “bads.” Other diseases like influenza and smallpox would operate in just the same way. Bad sanitation that swept away people with cholera and dysentery would have just the same affect. There are wasting diseases that weaken people a long time before killing them. But in the pre-industrial world most variation in mortality was from stuff that killed children or let them live.

Infanticide, which again takes people without disrupting production, was all good in terms of living standards in this world. The strong Christian prohibition of this would just reduce material living standards compared to the Roman world, or Tahiti, where it seems to have been common.

In the light of (1) and (2) I stand by my conclusions on the paradoxical nature of the Malthusian era.