More than any other scholar, Ernst B. Haas deserves to be known as the founding father of neofunctionalism. Haas has developed the idea of regional integration through functional cooperation on ‘nonpolitical’ issues, which would in fact lead to further integration in the geographical area concerned. However, even Haas himself had second thoughts right from the beginning of his studies about both the soundness of this “spill over” theory and neofunctionalism as a promising way to world peace.

One ardent supporter of functionalism has been David Mitrany.

The other names are the ones supporting legalist approach.