The one question in science is about the truth of a theory, i.e. its material and formal consistency: “In order to tell the politicians and practitioners something about causes and best means, the economist needs the true theory or else he has not much more to offer than educated common sense or his personal opinion.” (Stigum)
Economists do not have the true theory. They have many opinions but nothing in the way of scientific knowledge. Since the founding fathers, there is political economics and theoretical economics. The main differences are: (i) The goal of political economics is to successfully push an agenda, the goal of theoretical economics is to successfully explain how the actual economy works. (ii) In political economics anything goes; in theoretical economics, the scientific standards of material and formal consistency are observed.
The fact is that the agenda pushers of political economics have captured theoretical economics (= science) from the very beginning with the result that economics has produced nothing of scientific value in the last 200+ years. The major approaches ― Walrasianism, Keynesianism, Marxianism, Austrianism ― are mutually contradictory, axiomatically false, materially/formally inconsistent, and all got the foundational concept of the subject matter ― profit ― wrong.#1, #2
Economics is what Feynman called a cargo cult science and neither right-wing nor left-wing economic policy guidance ever had sound scientific foundations since the soapbox economists Adam Smith and Karl Marx. At present, neither Krugman nor Wren-Lewis nor Keen nor Varoufakis nor the rest of political loudspeakers, amateur journalists, bloggers, and blatherers can back up their political agenda pushing with a scientifically acceptable economic theory.
Scientific ethics forbids economists to dabble in politics. This is the one thing. The other thing is that economists have NOTHING of scientific value to add to the discussion and the political process.
#1 For details of the big picture see cross-references Failed/Fake Scientists
#2 For details of the big picture see cross-references Political Economics/Stupidity/Corruption
Related 'The economist as storyteller' and 'Circus Maximus: Economics as entertainment, personality gossip, virtue signaling, and lifestyle promotion' and 'How to make economics a science' and 'Your economics is refuted on all counts: here is the real thing'.