What’s Wrong with the Malthusian Argument?
I have let on both privately and in public that I am currently working on a book. This is a work in progress and still pretty much in flux. As the title suggests, it is supposed to be a critique of “An Essay on the Principle of Population,” which was first published in 1798 by Thomas Malthus.
I think this is one of the most influential works ever written. It is no understatement to say that it is the foundation of much of our worldview. But at the same time, I also believe that it was not only flawed, but completely wrong from the get-go. The basic contention is this:
Human populations will always grow given the opportunity, and actually as Malthus thinks at the maximum rate possible. He concedes that there are some imperfections and that reality only approximates what his theory predicts, but he is still confident that it is mostly correct.
The consequence is that human populations will grow until something stops them the hard way. Fertility is stuck at a high level, and only steeply rising mortality can do the trick. Modern readers know this is not true, and also Malthus and his contemporary readers knew it. Still those who think the Malthusian argument is correct assume that the conclusion held until about 1800. Afterwards, some weird things happened, and so now it is only true in a latent sense. One takeaway for many is that people in modern industrial societies are tricked into “unnatural” behavior. They should have extreme fertility, but something went wrong.
My contention is that this is false. Human populations have never done anything like this. They set a reasonable target for their population size and pursue it. Once they have reached it, fertility reverts to the replacement level, and that is what we see in modern industrial societies. It has happened many times before. That’s what humans have done throughout history, and what I think also many other species do. Hence Malthus has it backwards: Not rising mortality reins in the effect of stubborn procreation, but fertility matches a given level of mortality.
Human populations do grow and have often grown in the past. But this was a reaction to improving conditions. Since the underlying mechanism is imperfect, there can be some overshooting. So after a major boost to population, fertility should fall below the replacement level for some time before it converges to it from below. It is true that you will see shrinkage from a peak. But it is false to extrapolate from this and conclude that the respective population will die out. In other words: The democraphic panic that first gripped France about 150 years ago, Germany some hundred years ago, and that seems to be in full swing currently in the US is baseless.
I will write more about this as I go along. So stay tuned …
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Here’s an overview with all the articles and related ones in this series. There is also a short summary for each post, so you can follow the argument even if you don’t feel like reading everything. I will keep the list updated: