One of the earliest editions of this newsletter was a barely disguised letter of appreciation about David Roodman, a senior adviser at the Open Philanthropy Project with the unusual job description of compiling evidence on big, broad, important issues.
Roodman’s latest project is even bigger: He’s just released a new draft paper with the title “Modeling the Human Trajectory.” The very modest goal is to model how human economies have evolved since 10,000 BCE. You know, easy stuff.
Debate on social scientific questions is never “settled,” but Roodman’s past papers were useful because they came to relatively assured conclusions that it would take considerable subsequent research to overturn.
Reading his paper on the “human trajectory,” I came away with the belief that … human history is a beautiful mystery that we are only just beginning to unravel.
Roodman first tries to see, descriptively, how the growth rate of the world economy has evolved from 10,000 BCE to the present. He finds that it’s best represented by a power law distribution: that is, the economy hasn’t grown at a steady rate, accumulating to an exponential growth explosion, but instead the rate at which the world economy has grown has itself increased as the economy has gotten bigger.
If we follow this trajectory, that implies infinite or near-infinite growth over the next few thousand years. These are the kinds of projections that led environmentally minded economists and “systems thinkers” in the 1960s and ’70s to project some kind of bust; you can’t have infinite growth on a finite planet, as the slogan goes.
Those projections haven’t come to fruition yet, but that doesn’t mean the intuition is wrong, Roodman argues, asking: “What should we make of the fact that good models of the past project an impossible future?”
One possibility he explores is that this future is not in fact impossible. If, as the endogenous growth theory of economists like Paul Romer and Charles Jones has suggested in recent decades, technology, not raw materials, is the main driver of economic growth in the long run, maybe there isn’t a limit. “Technology” is just a term of art we use for human ideas and inventiveness, which doesn’t obey the restrictions of scarcity that apply to coal or rare-earth metals.
I am condensing a really dense and fascinating blog post about an even denser and more fascinating white paper that I absolutely do not have the math skills to fully grok, so forgive me if some is lost in translation. But I really encourage you to dive into Roodman’s post. He doesn’t arrive at a firm prediction of the future, naturally, but instead two much more modest observations:
“First, if the patterns of history continue, then some sort of economic explosion will take place again, the most plausible channel being AI. It wouldn’t reach infinity, but it could be big. Second, and more generally, I take the propensity for explosion as a sign of instability in the human trajectory. Gross world product, as a rough proxy for the scale of the human enterprise, might someday spike or plunge or follow complicated paths in between. The projections of explosion should be taken as indicators of the long-run tendency of the human system to diverge.”
My takeaway from the piece is arguably tautological but I think still useful: The difference between our best possible future and our worst possible future could be quite literally infinite. It could be the difference between civilization ending and the kind of abundance only dreamed of in science fiction.
That makes anything we can do to shape that long-term trajectory of humanity almost indescribably important. The hard part is finding out what, if anything, can reliably make that trajectory better.
From Vox’s Future Perfect newsletter: