My long answer was in Quiet Revolution in Welfare Economics, Princeton University Press, 1990. It took 15 years and a long book to come up with an answer that satisfied me to the question: what should a radical mean by efficiency? My short answer is: While radicals are right to be more worried about equity and participation than efficiency, inefficiency is surely not a good thing. To misuse people's work and/or the scarce productive resources we have -- that is to get less beneficial goods and services, less pleasurable work lives, or more destruction of the environment than is necessary -- is not a good thing. A good economy should be equitable and provide people with self-management but should also be efficient. Re capitalism: While capitalism is undesirble because it is inequitable and denies most people effective self-management opportunities and undermines human solidarity, it is also undesirable because, contrary to its champions' claims, it is highly inefficient. While capitalism is the most ENERGETIC economy humans have come up with to date -- I am thinking in comparison to feudalism for example -- it sets people off at frequently high levels of energy in very inefficient directions. Briefly, that is what I was referring to when I said that there are compelling "efficiency" critiques of capitalism.