Puzzeling to me, one theory or three?

Ok, now I’m confused. Professor Clark has completely and utterly convinced me that human economic life is properly explained, through most of history, via Malthusian theory. This may come as a surprise to some who’ve seen previous posts where, for example, I lambaste Jared Diamond for being a Malthusian and I provide data on how it can’t be the case that inputs are linearly growing while demand grows exponentially.

In Professor Clark’s upcoming book, “Conquest of Nature,” he lays out the implications of the Malthusian way of looking at things (see specifically “Malthusian Equilibrium” in chapter two). According to this model, standard of living is only dependent on a culturally fixed birth rate and a death rate that inversely depends on the standard of living (i.e. if standards of living increase, the death rate decreases). Technology change is just a shift in the technology schedule such that for each population level there’s a higher standard of living. Improved technology improves living standards which has the effect of increasing people’s life span. The increased life span means that there’s more people around, in turn decreasing the standard of living (e.g. the amount of food per person goes down). The decreased standard of living, decreases the death rate until the population is back into equilibrium (births equals deaths).

The only effect of the improved technology was to permanently increase the number of mouths to feed.

Worst for my anti-Malthusian case is that the data is there to back that theory up. The only effect of increases in technology through, let’s say, the 17th century was to increase the population. Shocks to the society (e.g. plagues, new farming techniques, even moving from a hunter/gathering to an agrarian society) resulted in unsustained changes in the standard of living. Clark has convinced me that Malthus was right.

At the same time, I’m also convinced that countries experience a demographic transition as they modernize. The timing differ from country to country but the pattern is clear. Countries start with high birth/death rates and these rates are generally equal (i.e. the population is stable). As countries first begin to develop their death rates fall and then a couple generations later their birth rates fall. This results in an s-curve expansion of population. Population quickly starts to increase as death rates decline, then the rate of increase slows as the birth rate begins to decline and then the population tops out when death rates equal birth rates again. We see this pattern over and over again, across countries and time.

Of course, these data don’t comport with the Malthusian model. Birth rate doesn’t change in that model and decreases in the death rate don’t coincide with increases in the standard of living. But there the data is…

There’s support for Malthus’ model before about 1800. There’s sustained and repeated demographic transitions after that date. What gives?

Are historians content with having two models of development (or lack there of). One that describes the world before the industrial revolution and one, incompatible with the first, that describes the world after the industrial revolution? Of course, you’d need a third theory that describes the transition. If I were a historian, I wouldn’t be happy with this situation at all. I’d want one theory, not three.

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