The Roots of Progress

Why you, personally, should want a larger human population

A bigger world is better for everyone

What is the ideal size of the human population?

One common answer is “much smaller.” Paul Ehrlich, co-author of The Population Bomb (1968), has as recently as 2018 promoted the idea that “the world’s optimum population is less than two billion people,” a reduction of the current population by about 75%. And Ehrlich is a piker compared to Jane Goodall, who said that many of our problems would go away “if there was the size of population that there was 500 years ago”—that is, around 500 million people, a reduction of over 90%. This is a static ideal of a “sustainable” population.

Regular readers of this blog can cite many objections to this view. Resources are not static. Historically, as we run out of a resource (whale oil, elephant tusks, seabird guano), we transition to a new technology based on a more abundant resource—and there are basically no major examples of catastrophic resource shortages in the industrial age. The carrying capacity of the planet is not fixed, but a function of technology; and side effects such as pollution or climate change are just more problems to be solved. As long as we can keep coming up with new ideas, growth can continue.

But those are only reasons why a larger population is not a problem. Is there a positive reason to want a larger population?

I’m going to argue yes—that the ideal human population is not “much smaller,” but “ever larger.”

Selfish reasons to want more humans

Let me get one thing out of the way up front.

One argument for a larger population is based on utilitarianism, specifically the version of it that says that what is good is the sum total of happiness across all humans. If each additional life adds to the cosmic scoreboard of goodness, then it’s obviously better to have more people (unless they are so miserable that their lives are literally not worth living).

I’m not going to argue from this premise, in part because I don’t need to and more importantly because I don’t buy it myself. (Among other things, it leads to paradoxes such as the idea that a population of thriving, extremely happy people is not as good as a sufficiently-larger population of people who are just barely happy.)

Instead, I’m going to argue that a larger population is better for every individual—that there are selfish reasons to want more humans.

First I’ll give some examples of how this is true, and then I’ll draw out some of the deeper reasons for it.

More geniuses

First, more people means more outliers—more super-intelligent, super-creative, or super-talented people, to produce great art, architecture, music, philosophy, science, and inventions.

If genius is defined as one-in-a-million level intelligence, then every billion people means another thousand geniuses—to work on all of the problems and opportunities of humanity, to the benefit of all.

More progress

A larger population means faster scientific, technical, and economic progress, for several reasons:

In fact, these factors may represent not only opportunities but requirements for progress. There is evidence that simply to maintain a constant rate of exponential economic growth requires exponentially growing investment in R&D. This investment is partly financial capital, but also partly human capital—that is, we need an exponentially growing base of researchers.

One way to understand this is that if each researcher can push forward a constant “surface area” of the frontier, then as the frontier expands, a larger number of researchers is needed to keep pushing all of it forward. Two hundred years ago, a small number of scientists were enough to investigate electrical and magnetic phenomena; today, millions of scientists and engineers are productively employed working out all of the details and implications of those phenomena, both in the lab and in the electrical, electronics, and computer hardware and software industries.

But it’s not even clear that each researcher can push forward a constant surface area of the frontier. As that frontier moves further out, the “burden of knowledge” grows: each researcher now has to study and learn more in order to even get to the frontier. Doing so might force them to specialize even further. Newton could make major contributions to fields as diverse as gravitation and optics, because the very basics of those fields were still being figured out; today, a researcher might devote their whole career to a sub-sub-discipline such as nuclear astrophysics.

But in the long run, an exponentially growing base of researchers is impossible without an exponentially growing population. In fact, in some models of economic growth, the long-run growth rate in per-capita GDP is directly proportional to the growth rate of the population.

More options

Even setting aside growth and progress—looking at a static snapshot of a society—a world with more people is a world with more choices, among greater variety:

Deeper patterns

When I look at the above, here are some of the underlying reasons:

All of these create agglomeration effects: bigger societies are better for everyone.

A dynamic world

I assume that when Ehrlich and Goodall advocate for much smaller populations, they aren’t literally calling for genocide or hoping for a global catastrophe (although Ehrlich is happy with coercive fertility control programs, and other anti-humanists have expressed hope for “the right virus to come along”).

Even so, the world they advocate is a greatly impoverished and stagnant one: a world with fewer discoveries, fewer inventions, fewer works of creative genius, fewer cures for diseases, fewer choices, fewer soulmates.

A world with a large and growing population is a dynamic world that can create and sustain progress.

For a different angle on the same thesis, see “Forget About Overpopulation, Soon There Will Be Too Few Humans,” by Roots of Progress fellow Maarten Boudry.

Comment: Progress Forum, LessWrong, Reddit

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