The Equilibrium Problem

In Ruhi Çenet’s documentary on Burundi, a man transports goods on a bicycle, 32 kilometers a day. He makes $23 a month.

My first thought was logistic: an inefficiency a proper logistics company could fix. Replace the bicycle with a motorcycle, add route optimization, and suddenly that $23 becomes ten times more. A dream market for anyone who can navigate the local bureaucracy.

The longer I sat with it, the more I realized the inefficiency wasn’t logistical. It was baked into the structure.

The Bicycle as a Window

$23 a month. About $0.75 a day. The man isn’t running a business — he’s surviving. His labor is so cheap that human muscles still outcompete machines at the margin. Not because bicycles beat trucks, but because capital is absent, credit is absent, and the labor pool is so deep that the price of a day’s work has bottomed out at bare subsistence.

The same pattern runs across the Global South: populations so large relative to productive capital that labor becomes disposable. You can replace that courier for $0.75 a day. The system doesn’t need him — it needs a body.

Why does this persist? The land is fertile. Burundi isn’t a desert. The country could feed itself. The knowledge of subsistence farming is ancient, not advanced. And yet.

The Aid Trap

Follow the chain. Food aid arrives, fewer children die, population grows. The same plots get split more ways, per-capita output drops. More aid arrives to fill the gap — people survive but don’t thrive. Nobody builds the non-farm economy because aid and subsistence are good enough to prevent collapse. Every year, the gap between what people need to be self-sufficient and what they can produce widens.

What looks like humanitarian intervention is, at the system level, a demographic debt that compounds every generation. You keep people alive without making them viable. The population grows beyond what local resources can carry, and now you need the aid forever just to stop the crash. Cut it off and you get famine. Keep it flowing and you get perpetual dependency.

The Black Death is the inverse. When a third of Europe died in the 14th century, the survivors had more resources. Labor became scarce overnight. Serfs who were worth a bowl of porridge suddenly could demand wages, negotiate terms, move freely. The feudal lords tried to reverse it — wage caps, forced labor laws — but the math was against them. The Peasant’s Revolt followed. Feudalism cracked open.

The lesson is uncomfortable: population collapse benefited the survivors not because death is good, but because labor scarcity shifted bargaining power downward. The people at the bottom gained leverage for the first time in centuries.

The inverse is what we see today. When labor is abundant, humans are fungible. When labor is scarce, humans are valuable.

The Feudal Logic of Population

Follow that chain to its endpoint: population growth disproportionately benefits the people at the top. Land, capital, distribution networks, political connections — these are fixed resources. More people means more competition for access, which means the owners can extract more rent for the same asset. The Black Death broke that dynamic. Modern aid perpetuates it.

A farmer on half a hectare trying to feed eight people can’t produce a surplus. He can barely keep everyone alive. Eight chronically malnourished people are less productive, less healthy, and less capable of escaping the trap than three well-nourished ones would be. The same land, with fewer people, produces more total human welfare — not less.

But this implies a trade-off between the living and the hypothetical not-yet-born, between rights to ancestral land and the practical math of subsistence. And that trade-off is politically radioactive.

What a Humane Equilibrium Looks Like

Lower bound: enough people that specialization works. A village of 150 can’t sustain a physicist or a neurosurgeon. You need a critical mass for civilization.

Upper bound: not so many people that labor is disposable. A world where replacing a human costs nothing in practice is a world where human dignity is a luxury, not a given.

One useful heuristic: the optimal population is where the median person can achieve dignified self-sufficiency on 40 hours of work per week. If the system requires 60+ hours for bare survival, you’re past the ceiling. If 20 hours covers your needs, you have room to grow.

By that metric, much of the world is way past the ceiling. The bicycle man in Burundi is working more hours for less dignity than a medieval serf.

The cities that produced the most innovation per capita weren’t the biggest. Florence had ~60,000 people. Classical Athens ~40,000. Bangalore was ~500,000 during its tech boom before hitting 14 million and collapsing into traffic and smog. There’s a sweet spot — enough minds for critical mass, not so many that coordination costs and competition drown everything out.

The Shirt Problem

I am a software engineer in Germany. From here, the equilibrium looks enviable. High wages, short work weeks, clean air, functional healthcare. But it only works because Bangladesh’s equilibrium is broken. The $3 shirt I can buy exists because someone in Dhaka works 14-hour days in a tin shed for $150 a month. If Bangladesh reached its own equilibrium — higher wages, shorter hours, better conditions — that shirt becomes $25, and my living standard adjusts downward.

The peaks are coupled. There are no independent equilibriums. The global poor subsidize the global comfortable. Every time you optimize labor costs in one place, you shift the burden to another.

The system isn’t failing. It is functioning exactly as the incentives dictate.

So when I talk about “optimal population,” the question becomes: optimal for whom? The global maximum approach implies some world authority calibrating population to resources — a utopian vision that’s one bad leader away from totalitarianism. The local peaks approach is more honest but falls apart when you follow the supply chain.

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Every link in that chain is bolted together by a single question: who decides?

The man on the bicycle doesn’t decide where he’s born, how much land his family has, what his government does, whether aid flows or stops, or what his labor is worth on the global market. He just cycles. 32 km a day. $23 a month. Inside a system he never chose, can’t influence, and that doesn’t need him to be anything more than cheap.

All the theory — the aid trap, the demographic debt, the equilibrium models, the shirt problem — they’re conversations other people get to have. The people inside the disequilibrium don’t even have a voice in it.

That’s the real inefficiency. Not the bicycle. Not the logistics. Not the land distribution. It’s that the people who most need the system to change have the least power to change it.

If a place is structurally unable to reach a dignified equilibrium — too landlocked, too resource-poor, too fragmented — what then? Every person born into that system either suffers their whole life, migrates and depresses wages somewhere else, or gets supported by aid that perpetuates the dependency cycle. All three are bad. You could follow the logic to radical answers — population planning, forced redistribution, mass relocation — and every one of them has been tried somewhere, by someone, with good intentions and bloody outcomes. Not because the math was wrong, but because the implementation was captured by the worst people.

So the real question isn’t “is there an optimal population?” The math says yes, probably. The question is: who decides? And if you follow that far enough, you arrive at the only answer that ever sticks.

It depends on who is in control.

The man on the bicycle was never the problem. He was never even in the room. He cycles 32 kilometers a day inside a system maintained by people who will never know his name.

That system isn’t a law of nature. As Varys told Tyrion in Game of Thrones: power resides where men believe it resides. It is a trick, a shadow on the wall.

Right now, the shadow is casting a very long dark line over Burundi. And as long as we believe the shadow is real, the man will keep pedaling.