The Malthusian Trap?

by Jason Crawford · May 21, 2017 · 2 min read

One idea I’ve heard repeatedly is that before the Industrial Revolution, people were stuck in a “Malthusian Trap”. E.g., from this blog post in The Atlantic:

In the thousands of years before the Industrial Revolution, civilization was stuck in the Malthusian Trap. If lots of people died, incomes tended to go up, as fewer workers benefited from a stable supply of crops. If lots of people were born, however, incomes would fall, which often led to more deaths. …

A followup post adds:

After a plague, a roughly stable supply of food and goods shared among a smaller number of people made everybody richer. That is, until births rose, and incomes fell again.

Something about this doesn’t quite make sense to me. Why is the “supply of food and goods” “roughly stable”? That supply is still produced by people. More people, more work, more goods. If people die, why does the food just keep coming? If people are born, can’t they work and produce?

Now, maybe the limiting factor at some point is not labor but land. Surely, given a certain level of technology, there is a certain carrying capacity to the land. Maybe civilization was right at that point?

But then, say more people are born, but there isn’t enough land for them all to work productively. What happens? Are the farms overstaffed, with hands who don’t have enough to do? Is there unemployment? But it’s not as if everyone, even in ancient times, worked on farms. Wouldn’t people leave farms and try to find another craft? Or was the pull of tradition too strong?

Or maybe I’m being a little anachronistic by even trying to analyze pre-industrial societies in terms of economic concepts like unemployment? I don’t know much about feudal Europe, but as I recall, serfs worked the land without owning it. Maybe if there were more people, they just got smaller plots of land to work? Maybe there was no market for labor to speak of?

But also, if a population is at the carrying capacity of the land, wouldn’t that spur migrations? Wouldn’t the people without farms head off in search of land? Was Europe already saturated? Was India? Was China??

And is the idea that every industry is at capacity? So, not only is there not enough land to farm, but there aren’t enough mines to dig, there’s not enough cotton to spin, there aren’t enough fish to catch, there aren’t enough bricks to lay, there aren’t enough trees to cut, etc. Because if there were capacity in any of these areas, the “extra” people could go work there and increase the overall wealth of an economy. (Again, assuming there is some labor mobility.)

I suppose, conceivably, that without the right technology you’d have an imbalance of goods in the economy. So maybe people can smelt a lot of iron, but that just makes iron relatively cheap while people are starving because food is expensive.

But anyway, if you want to explain why GDP per capita was roughly flat for thousands of years, isn’t the answer simply that productivity didn’t increase much because technology wasn’t advancing much?

And if you want to explain why GDP per capita went up and down over the centuries, as in the last graph in part 3 of that blog post series, then aren’t there probably other factors, like variations in climate affecting agricultural output?

In any case, the whole notion of the Malthusian Trap, even as something that was only operative in the technologically stagnant pre-industrial world, just doesn’t sit right with me. It seems to assume a static flow of goods, ignoring the fact that goods are produced by people. I don’t understand it.

Update: See the followup with a bit more analysis.