It was his capacity in the field of macroeconomics avant la lettre that qualified. [fact]
While his clarity and strong convictions in this area qualified him for membership in the Mont Pèlerin Society, it was his capacity in the field of macroeconomics avant la lettre that qualified him for the League's roster of economists and the WLC in the first place.
Dieter Plehwe, Quinn Slobodian & Philip Mirowski (eds.), Nine Lives of Neoliberalism, loc. 390