"But it will be argued that since the sole elements of which society is composed are individuals, the primary origin of sociological phenomena cannot be other than psychological. Reasoning in this way, we can just as easily establish that biological phenomena are explained analytically by inorganic phenomena. It is indeed certain that in the living cell there are only molecules of crude matter. But they are in association, and it is this association which is the cause of the new phenomena which characterise life, even the germ of which it is impossible to find in a single one of these associated elements. This is because the whole does not equal the sum of its parts; it is something different, whose properties differ from those displayed by the parts from which it is formed... By virtue of this principle, society is not the mere sum of individuals, but the system formed by their association represents a specific reality which has its own characteristics... The group thinks, feels and acts entirely differently from the way its members would if they were isolated. If therefore we begin by studying these members separately, we will understand nothing about what is taking place in the group. In a word, there is between psychology and sociology the same break in continuity as there is between biology and the physical and chemical sciences. Consequently every time a social phenomenon is directly explained by a psychological phenomenon, we may rest assured that the explanation is false."
January 1, 1970
https://en.wikiquote.org/wiki/Emergence