Implicit in that argument is the assumption that we must maintain existing levels of productivity to create a decent socialist society. Abstract Hayekian arguments about the efficiency of markets aside (yeah,
I couldn't resist blowing a raspberry at andie), it is possible to provide adequate resources to people using socialist strategies, even if those strategies don't generate high levels of "productivity" in the formal economic sense. --Examples: public roads, libraries, the creation of the Internet, universal health care, basic scientific knowledge and research.
It's actually pretty simple math: When we don't have to divert a sizeable chunk of the resources to a small number of capitalists, there are more resources to spread around. Thus capitalist levels of economic productivity are unnecessary in a socialist society.
Miles