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A quick look at the web site of the _post-autistic economics review_ (http://www.paecon.net) finds a page titled 'The Greatest 20th Century Economists Poll'.
Qualification is defined as:
"“Greatest” here means ... who most added to our understanding of economic phenomena ... Only subscribers to the post-autistic economics review are eligible to vote"
Friedman is off the back from #1 Keynes (3,253 votes) and well back from #4 Amartya Sen (708 votes) or #6 Thorstein Veblen (591 votes) - but he is #13, right behind Kenneth Arrow and well above Coase.
Friedman's theories are surely open to question on social and political grounds and the criticisms of the heterodox economists are cogent, but even they don't hold his thinking in contempt, just his conclusions.