“General chemistry is sometimes defined as ‘the science of atoms and their behavior.’ The same chemists who use this definition acknowledge that they have never discovered the hypothetical ‘free atom.’ The only close likeness in this respect that I can discover between general sociology and general chemistry or biology is in the fact that we must use the conception of human individuals, although we can find no such object in reality as the free individual. If we should describe sociology as ‘the science of human individuals and their behavior’ we should be in verbal uniformity with one way of defining chemistry; but I do not see any profit from that fact in the shape of more knowledge about society. Unless we are willing however, to take as our ultimate concept ‘the human atom,’ ‘the individual,’ ‘the social man,’ or whatever we may choose to name the irreducible element in societary combinations, I see nothing but arbitrariness in the plan of adopting a ‘unit of inquiry.’ Is it not a purely gratuitous assumption that at present sociology needs or can use a unit of inquiry in the sense to which Professor Lindsay seems most to incline?”