Green Mars. Kim Stanley Robinson

surfboards, or long folded birdsuits. As they passed he recognised the faces of the previous night’s kitchen crew, and also their driver. The driver waved and continued up the path. Art walked down it to the lagoon. The low sound of waves mumbled through the salty air, and birds swam in the reeds.

      After a while Art went back up the trail, and in the compound’s dining room he found the elderly workers back in the kitchen, flipping pancakes. After Art and the rest of the guests had eaten, yesterday’s driver led them upstairs to a large meeting room. They sat on couches arranged in a square. Big picture windows in all four walls let in a lot of the morning’s grey light. The driver sat on a chair between two couches. “I’m William Fort,” he said. “I’m glad you’re all here.”

      He was, on closer inspection, a strange-looking old man; his face was lined as if by a hundred years of anxiety, but the expression it currently displayed was serene and detached. A chimp, Art thought, with a past in lab experimentation, now studying Zen. Or simply a very old surfer or hang-glider (which had he been carrying?), weathered, bald, round-faced, snub-nosed. Now taking them in one by one. Sam and Max, who had ignored him as driver and cook, were looking uncomfortable, but he didn’t seem to notice. “One index,” he said, “for measuring how full the world is of humans and their activities, is the percent appropriation of the net product of land-based photosynthesis.”

      Sam and Max nodded as if this were the usual way to start a meeting.

      “Can I take notes?” Art asked.

      “Please,” Fort said. He gestured at the coffee table in the middle of the square of couches, which was covered with papers and lecterns. “I want to play some games later, so there’s lecterns and workpads, whatever you like.”

      Most of them had brought their own lecterns, and there was a short silent scramble as they got them out and running. While they were at it Fort stood up and began walking in a circle behind their couches, making a revolution every few sentences.

      “We now use about eighty percent of the net primary product of land-based photosynthesis,” he said. “One hundred percent is probably impossible to reach, and our long range carrying capacity has been estimated to be thirty percent, so we are massively overshot, as they say. We have been liquidating our natural capital as if it were disposable income, and are nearing depletion of certain capital stocks, like oil, wood, soil, metals, fresh water, fish, and animals. This makes continued economic expansion difficult.”

      “Difficult!” Art wrote. “Continued?”

      “We have to continue,” Fort said, with a piercing glance at Art, who unobtrusively sheltered his lectern with his arm. “Continuous expansion is a fundamental tenet of economics. Therefore one of the fundamentals of the universe itself. Because everything is economics. Physics is cosmic economics, biology is cellular economics, the humanities are social economics, psychology is mental economics, and so on.”

      His listeners nodded unhappily.

      “So everything is expanding. But it can’t happen in contradiction to the law of conservation of matter-energy. No matter how efficient your throughput is, you can’t get an output larger than the input.”

      Art wrote on his note page, “Output larger than input—everything economics—natural capital—Massively Overshot.”

      “In response to this situation, a group here in Praxis has been working on what we call full world economics.”

      “Shouldn’t that be overfull world?” Art asked.

      Fort didn’t appear to hear him. “Now as Daly said, manmade capital and natural capital are not substitutable. This is obvious, but since most economists still say they are substitutable, it has to be insisted on. Put simply, you can’t substitute more sawmills for fewer forests. If you’re building a house you can juggle the number of power saws and carpenters, which means they’re substitutable, but you can’t build it with half the amount of lumber, no matter how many saws or carpenters you have. Try it and you have a house of air. And that’s where we live now.”

      Art shook his head and looked down at his lectern page, which he had filled again. Before clicking to a new one he read it: “Resources and capital non-substitutable—power saws/carpenters—lumber—house of air.”

      Fort was looking out the west window, down to the beach. A few minutes passed, and he did not go on.

      “Excuse me?” Sam said. “Did you say natural capital?”

      Fort jerked, turned around to look at Sam. “Yes?”

      “I thought capital was by definition manmade. The produced means of production, we were taught to define it.”

      “Yes. But in a capitalist world, the word capital has taken on more and more uses. People talk about human capital for instance, which is what labour accumulates through education and work experience. Human capital differs from the classic kind in that you can’t inherit it, and it can only be rented, not bought or sold.”

      “Unless you count slavery,” Art said.

      Fort’s forehead wrinkled. “This concept of natural capital actually resembles the traditional definition more than human capital. It can be owned and bequeathed, and divided into renewable and nonrenewable, marketed and nonmarketed.”

      “But if everything is capital of one sort or another,” Amy said, “you can see why people would think that one kind was substitutable for another kind. If you improve your manmade capital to use less natural capital, isn’t that a substitution?”

      Fort shook his head. “That’s efficiency. Capital is a quantity of input, and efficiency is a ratio of output to input. No matter how efficient capital is, it can’t make something out of nothing.”

      “New energy sources…” Max suggested.

      “But we can’t make soil out of electricity. Fusion power and self-replicating machinery have given us enormous amounts of power, but we have to have basic stocks to apply that power to. And that’s where we run into a limit for which there are no substitutions possible.”

      Fort stared at them all, still displaying that primate calm that Art had noted at the beginning. Art glanced at his lectern screen. “Natural capital— human capital— traditional capital— energy vs. matter— electric soil— no substitutes please—” He grimaced and clicked to a new page.

      Fort said, “Unfortunately, most economists are still working within the empty world model of economics.”

      “The full world model seems obvious,” Sally said. “It’s just common sense. Why would any economist ignore it?”

      Fort shrugged, made another silent circumnavigation of the room. Art’s neck was getting tired.

      “We understand the world through paradigms. The change from empty world economics to full world economics is a major paradigm shift. Max Planck once said that a new paradigm takes over not when it convinces its opponents, but when its opponents eventually die.”

      “And now they aren’t dying,” Art said.

      Fort nodded. “The treatments are keeping people around. And a lot of them have tenure.”

      Sally looked disgusted. “Then they’ll have to learn to change their minds, won’t they.”

      Fort stared at her. “We’ll try that right now. In theory at least. I want you to invent full world economic strategies. It’s a game I play. If you plug your lecterns into the table, I can give you the starting data.”

      They all leaned forward and plugged into the table.

      The first game Fort wanted to play involved estimating maximum sustainable human populations. “Doesn’t that depend on assumptions about lifestyle?” Sam asked.

      “We’ll make a whole range of assumptions.”

      He wasn’t kidding. They went from scenarios in which