Nobody can prove anything in any scientific way, however.
This is a problem. Assertions become adopted because they support a desired action and become accepted fact. Then even when better, more descriptive theories come along, the old ideas are impossible to budge. In the case of real science, look how quickly the luminous aether, Newtonion mechanics and other outdated models were replaced (even in the face of strong opposition often). For comparison,
Keynesianism New neoclassical synthesis( Monetarists ) is stubbornly holding on in the face of almost overwhelming circumstantial evidence of its abysmal failure.
So through my Bitcoin inspired education I would like to add / amended your statement.
Keynesianism died in 1971 with the abolishing of the gold standard, Neo-Keynesian economics died with the Monetarists during the Reagan and Thatcher revolution. It is during this revolution that Hayek's, Austria free market ideals are perverted by Milton Friedman who leads the creation of the Monetarism model we have today.
In my view the very worst of the negative side effects of central planning materializing the very worse possible outcome of the free market serving the needs of humanity.
The result is a separation of a sustainable system into to mutually apposed conflicting systems. Ecosystem and Economic system.