I have been thinking recently about the question of would humans and autonomous intelligent robots trade. The first guess would be yes, since humans and robots would have different opportunity costs of doing different tasks, and therefore comparative advantage would apply.
From "The Shape of Automation", 1960, H. O. Simon:
"""The change in the occupational profile depends on a well-known economic principle, the doctrine of comparative advantage. It may seem paradoxical to think that we can increase the productivity of mechanized techniques in all processes without displacing men somewhere. Won't a point be reached where men are less productive than machines in all processes, hence economically unemployable? (Footnote in article: The difficultly that laymen find with this point underlies the consistent failure of economists to win wide general support for the free-trade argument. The central idea--that comparative advantage, not absolute advantage, counts--is exactly the same in the two cases. )
The paradox is dissolved by supplying a missing term. Whether man or machines will be employed in a particular process depends not simply on their relative productivity in physical terms, but on their cost as well. And cost depends on price. Hence--so goes the traditional argument of economics--as technology changes and machines become more productive, the prices of labor and capital will so adjust themselves as to clear the market of both. As much of each will be employed as offers itself at the market price, and the market price will be proportional to the marginal productivity of that factor. By the operation of the marketplace, manpower will flow to those processes in which its productivity is comparatively high relative to the productivity of machines; it will leave those processes in which it productivity is comparatively low. The comparison is not with the productivities of the past but among the productivites in different processes with the currently available technology. """
I can think of three ways (one was stolen from wikipedia) that comparative advantage would fail.
The first is if there is a scarce non-time resource and there is a substantial difference in the quantity of the scarce resource consumed. For example if A uses 2 tons of iron to make a car and B uses 1 ton of iron, and iron is scarce, then B can make more cars absolutely.
The second is that there is a wage floor (or utility floor). If the wage so low human cannot live on it, then the wage cannot get low enough to make trade beneficial.
The third is from the Wikipedia comparative advantage article http://en.wikipedia.org/wiki/Comparitive_advantage , and is that the transactions costs can eat away the benefits from trade.
Basically, at some point robots reach the point where they make the decision of do they keep trading with humans. If there is no benefit for the robots (that is no point for trade from the robots point of view), will they keep helping humans, or will humans be once again on our own. I can't even think of any science fiction where independent robots trade physical goods with humans (in Always Coming Home by Ursula K. Le Guin, the humans and artificial intelligences do give each other information).
