Economics is a social science, not like physics, where there tends to be more consensus, and yet in physics there are paradigm shifts. To this we have to add the fact that ideology is imbricated in economics, which makes objective knowledge more difficult, so to speak. But there are things on which there is consensus and they work, such as, for example, that raising interest rates serves to lower inflation, and lowering them to stimulate economic growth.

Regarding the meltdown you ask about, it is relative because a left-wing economist will tell you that what is going wrong is because not enough regulations and state control have been established and someone on the right will tell you the opposite, precisely that the economy is going wrong because it has not been deregulated and liberalised enough.