At first, it sounds obvious: if we want to save the planet, we should do less. Fewer people, less consumption, smaller footprints. I believed this too—so much so that I once thought having kids was irresponsible. But the more I looked into it, the less sense it made. Physicist David Deutsch has a radical view: all failures are knowledge failures. Pollution isn't proof we've hit Earth's limits—it's proof we haven't figured out the right solutions yet. The laws of physics permit clean abundance; we just need to discover how. Think of it like alchemy. For centuries, turning lead into gold seemed impossible—until we discovered nuclear physics. What looks like pollution today is just valuable matter in the wrong form, waiting for smarter minds to rearrange it. The only true limit is how many of those minds we have working on the problem. For instance, there's no law of physics that says more people must mean more carbon emissions. In the United States, GDP has more than doubled since 1990, but per-capita CO2 emissions have actually decreased by 30% over the same period. Is this because we have offshored much of our manufacturing to China? Partly. But China's GDP grew 14x since 1990 while their CO2 emissions only increased 5 times. It is widely believed that China's carbon emissions will peak this year as they replace their coal power stations with nuclear. In short: we have decoupled carbon emissions from growth. Carbon isn't the price of progress—it's just a sign we're using outdated tech. The stone age didn't end because we ran out of stones. It ended because we invented bronze. How about resources, aren't we running out of those? In 1980, Stanford biologist Paul Ehrlich made a famous wager with upstart economist Julian Simon. Ehrlich—author of The Population Bomb—was certain humanity was headed for collapse. More people meant more resource consumption, driving prices up as scarcity took hold. It seemed obvious. So they bet $1,000 on the future price of five industrial metals (chromium, copper, nickel, tin, and tungsten). If prices rose over the next decade, Ehrlich won. If they fell, Simon did. Ten years later, every single metal was cheaper—despite a global population increase of 800 million. Why? Because Ehrlich made a fatal error: he assumed resources were static. But humans don’t just consume—we innovate. When copper got expensive, we found ways to use less (fiber optics replaced phone wires). When tin prices spiked, companies switched to aluminum cans. Oil was worthless sludge until we invented refineries; sunlight was just weather until we built solar panels. But how about land, surely we’re running out of that? It seems intuitive that as a population grows we’d need more land to feed and house them, but the data shows that we're learning to do more with less. In 1960, feeding one person required 1.2 acres of farmland. Today? Just 0.5 acres, thanks to high-yield crops and precision agriculture. The Netherlands, a country smaller than West Virginia, is now the world’s second-largest food exporter—using vertical farms and AI-driven greenhouses that grow tomatoes with 90% less water. Meanwhile, global forest cover has expanded by an area larger than France since 1982, as improved productivity frees up marginal land. The constraint was never space; it was knowledge. And the more knowledge we have, the more land we can return to nature. Cities are humanity's secret weapon. As Geoffrey West's research in Scale shows, when you double a city's population, you don't just get double the output—you get roughly 15% more innovation per person. More collisions between minds mean more breakthroughs. The printing press, the steam engine, the smartphone—none were inevitable. They emerged because enough people were packed together, thinking and trading ideas. This explains why human progress doesn't just add—it compounds. More people don't just mean more labor; they mean more possible connections between ideas. One person's half-formed thought becomes another's world-changing invention. The “have fewer kids” argument fails a simple test: children don’t just consume resources, they create solutions. Every additional human is a potential Marie Curie, Norman Borlaug, or the student who figures out fusion. The Industrial Revolution, the Green Revolution, the internet—all emerged during population booms. More people don't just mean more mouths to feed. It means more minds to invent, more hands to build. Progress scales with people. Telling people to have fewer kids to "save the planet" is like throwing the crew off a sinking ship to make it lighter. Sure, it buys time—but who's left to fix the leak? More people does mean more consumption—but we need to update our intuition that this is inherently bad. Demand isn’t just strain; it’s fuel for innovation. Take solar power: in 1975, a single watt of solar capacity cost between $70–$100 per watt. Today it’s 20 cents. That 500x drop didn’t happen because we used less energy—it happened because booming demand drove economies of scale, better manufacturing, and breakthroughs like perovskite cells. The same pattern—demand driving economies of scale—holds for batteries (costs down 90% since 2010), LED lighting (100x cheaper than 2000), and lab-grown meat (projected to undercut beef by 2030). Consumption isn’t the enemy—it’s the signal that tells innovators: "Solve this, and you’ll get rich." The more people who want something, the faster we make it cheaper, cleaner, and abundant. The future won't be saved by guilt or retreat, but by doubling down on humanity's greatest resource: people. Cities humming with ideas. Labs running on young curiosity. The next Norman Borlaug figuring out carbon-neutral protein, or the next Grace Hopper coding up climate models. We're not passengers on this planet—we're the engineers. Pollution isn't the end—it's an invitation to invent. And the more of us there are working on it, the faster we'll crack these problems: cleaning oceans, rewilding forests, turning emissions into resources, and diverting the next extinction-level asteroid. Sustainability isn't about making ourselves smaller. It's about making our potential limitless. Because in the long run, the only thing that's truly unsustainable is giving up.