Another way of putting it would be Simon (i.e., plenty) for capital
and Malthus (i.e., subsistence) for labor. That, of course, is Karl
Marx's vision of long-term economic development. And while I don't have
a strong opinion as to whether or not this is accurate over the long
term, it's certainly a plausible story about the future, and Marx's
solution--socialism--unquestionably seems to me to be the correct one.
Why, you ask?
If the "robots" are really mere machines, then it should be easy to
peacefully divide up the surplus more-or-less equitably, we'll
transition to socialism and everyone will be happy--it'll be like Star
I'm baffled. Yes, the robots will be mere machines. But these mere machines will be owned by people. And though these people will be awfully rich by our standards, even rich people rarely take the "transition to socialism" lying down. They (or their robot stewards) will have every reason to resist expropriation like any other capitalists. In the short-run, that means investing less and consuming more - and capital flight if the transition to socialism looks serious. In the long-run, it means far lower dynamic efficiency. Why tell your robots to figure out ways to increase productivity when you could instead tell them to figure out how to beat the system?
Even worse: Depending on what kind of "transition to socialism" you have in mind, you might want to reprogram your robots for civil war. That's how these transitions typically end. True, all the soldiers of the future may be robots. But as anti-pacifists like to remind us, "Those who don't own swords can still die upon them." Just because robots do all the killing doesn't mean humans won't do their share of the dying.
At first glance, I admit, a vision of a superabundant world where people who own only their labor eke out a meager existence seems frightening. But put your fears aside. In an ultra-productive world, a relatively tiny amount of non-labor resources would make your rich by current standards. Labor + zero non-labor assets = poverty; labor + token non-labor assets = riches. In any case, a slight charitable impulse in the better-off is all you need to ensure fabulous riches for every human on earth.
Once you've got a world this wonderful, the last thing you'd want to do is start down a potentially slippery slope with a high tech Russian Civil War at the bottom. Indeed, a more sensible reaction would be abolish the welfare state as obsolete. If half of us were billionaires, mopping up any residual human poverty with voluntary charity would be child's play.