I used to be a Malthusian. This was my mental model of the world: exploding population, small planet; it's going to lead to ugly things. But I'm moving past Malthus, because I think that we just might be about 150 years from a kind of new enlightenment.

Here's why. This is the U.N.'s population data, you may have seen, for the world. And the world's population expected to top out at something hopefully a bit less than 10 billion, late this century. And after that, most likely it's going to begin to decline. So what then? Most of the economic models are built around scarcity and growth. So a lot of economists look at declining population and expect to see stagnation, maybe depression. But a declining population is going to have at least two very beneficial economic effects.

One: fewer people on a fixed amount of land make investing in property a bad bet. In the cities, a lot of the cost of property is actually wrapped up in its speculative value. Take away land speculation, price of land drops. And that begins to lift a heavy burden off the world's poor.

Number two: a declining population means scarce labor. Scarce labor drives wages. As wages increase that also lifts the burden on the poor and the working class. Now I'm not talking about a radical drop in population like we saw in the Black Death. But look what happened in Europe after the plague: rising wages, land reform, technological innovation, birth of the middle class; and after that, forward-looking social movements like the Renaissance, and later the Enlightenment.

Most of our cultural heritage has tended to look backward, romanticizing the past. All of the Western religions begin with the notion of Eden, and descend through a kind of profligate present to a very ugly future. So human history is viewed as sort of this downhill slide from the good old days.

But I think we're in for another change, about two generations after the top of that curve, once the effects of a declining population start to settle in. At that point, we'll start romanticizing the future again, instead of the nasty, brutish past.

So why does this matter? Why talk about social-economic movements that may be more than a century away? Because transitions are dangerous times. When land owners start to lose money, and labor demands more pay, there are some powerful interests that are going to fear for the future. Fear for the future leads to some rash decisions. If we have a positive view about the future then we may be able to accelerate through that turn, instead of careening off a cliff.

If we can make it through the next 150 years, I think that your great great grandchildren will forget all about Malthus. And instead, they'll be planning for the future and starting to build the 22nd Century Enlightenment. Thank you. (Applause)