George Stigler in the lecture “Economics or Ethics?” (1980):
The proposition that economists are not addicted to taking frequent and disputatious policy positions will appear incredible to most non-economists, and implausible to many economists. The reason, I believe, for this opinion is that in talking to a non-economist, there is hardly anything in economics except policy for the economist to talk about. The layman is unequipped to discuss with an economist the problems that concern professional economics at any time: he would find that in their professional writing the well-known columnists of Newsweek are quite incomprehensible. The typical article in a professional journal is unrelated to public policy—and often apparently unrelated to this world. Whether the amount of policy-advising activity of economists is rising or falling I do not know, but it is not what professional economics is about.
The great economists, then, have not been preoccupied with preaching. Indeed, none has become great because of his preaching—but perhaps I should make an exception for Marx, whom some people rank as a great economist and I rank as an immensely influential one. The fact that the world at large thinks of us as ardent enthusiasts for a hundred policies is not pure error, but it tells more about what the world likes to talk about than what economics is about. The main task of economics has always been to explain real economic phenomena in general terms, and throughout the last two centuries we have adhered to this task with considerable faithfulness, if not always with considerable success.