Voilà ci dessous l’opinion de Draghi à propos des hommes politiques, en gros ils sont incompétents, ils ne pensent qu’à leur élection et leur réélection, ils mentent et nie qu’ils ont menti ensuite : "they renege", et Draghi conclu que : la crédibilité d’une banque centrale avec un mandat clair de stabilité des prix est mieux assuré par une banque centrale  :

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http://www.ecb.europa.eu/press/key/date/2017/html/ecb.sp170823.en.html

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In the 1970s governments attempted to maximise social welfare, in the form of low unemployment and inflation, by trying to exploit the short-run trade-off between the two. They engineered surprise booms “just once” before promising to revert to a policy of low inflation in future, especially when motivated by the electoral cycle. The insights of a number of Nobel laureates showed how these policies were bound to fail and why they were time inconsistent.[2] The same incentive to renege remains in the future, and promises to do otherwise lack credibility. Rational wage and price setters will not believe in a policy that policymakers will find it optimal to renege on, making it difficult for policymakers to achieve price stability without a recession.

It is hard to overestimate the enormous impact that the Lucas critique and the problem of time inconsistency have had on the conduct of monetary policy over the past 40 years. In the 1970s, most central banks were under political control and obliged to follow more or less short-term oriented policies. During the 1990s and 2000s, the importance of credibility was increasingly appreciated and evidence mounted that operationally independent central banks with a clear mandate to maintain price stability delivered much better economic outcomes than those under direct government control.