The whole is greater than the sum of parts, this is why reductionist ideas cannot account for what Life consists of. Like Mae-Wan Ho said:
“Life is a process of being an organizing whole. Life is a process and not a thing, nor a property of a material thing or structure. Life must therefore reside in the patterns of dynamic flows of matter and energy that somehow make the organisms alive, enabling them to grow, develop and evolve. From this, once can see that the “whole” does not refer to an isolated, monadic entity. It refers to a system open to the environment, that enstructures or organizes itself by simultaneously ‘enfolding’ the external environment and spontaneously ‘infolding’ its potential into highly reproducible or dynamically stable forms.”
If one follows Jean Staune in this path he could think that darwinists aren’t aware of synergy, or that it’s always true that « the whole is greater than the sum of parts », which is false in cases of antagonism. And this can’t even qualify reductionist approaches, one way or another. It would be as if saying that a chemist isn’t able to describe a chemical synthesis process because he considers electron transfers from one molecule to another.
Keynes like a lot the word « must« , but the « why » is quite absent here.
The meaning of this citation might be made clearer if the justifications of Kaynes are juxtaposed.