The mental consciousness likes to create castles in the air, developing theories and ideas that “make sense” and which represent a systematic and organized approach to things. The problem with applying this approach to human unity is that we are not dealing with inert material things which can be lined up, counted and built up, but rather, with vital reactions based on long history that are not so easily clubbed together.
The mind would look at natural language or cultural groupings, or perhaps racial groupings, and use that as the basis for large continental formations which would then interact on the world level with each other. A brief review of history however shows the limitations of this approach.
Sri Aurobindo notes: “It is easy to build up a system in the mind and propose to erect it on foundations which would be at first sight rational and convenient. At first sight it would seem that the unity of mankind could most rationally and conveniently arrange itself upon the basis of a European grouping, an Asiatic grouping, an American grouping, with two or three sub-groups in America, Latin and English-speaking, three in Asia, the Mongolian, Indian and West Asian, with Moslem North Africa perhaps as a natural annexe to the third of these, four in Europe, the Latin, Slavonic, Teutonic and Anglo-Celtic, the latter with the colonies that still chose to adhere to it, while Central and Southern Africa might be left to develop under present conditions but with the more humane and progressive principles upon which the sentiment of a united humanity would insist.”
The obstacles to this approach however are considerable, given historical reality: “… nations closely connected by every apparent tie, are actually divided by stronger antipathies than those more ideative and less actual which separate them from peoples who have with them no tie of affinity. Mongolian Japan and Mongolian China are sharply divided from each other in sentiment; Arab and Turk and Persian, although one in Islamic religion and culture, would not, if their present sentiments towards each other persisted, make an entirely happy family. Scandanavian Norway and Sweden had everything to draw them together and perpetuate their union, — except a strong, if irrational sentiment which made the continuance of that union impossible.”
Over time, the historical causes of these divisions could of course be resolved, potentially, but this is not something that can be imposed by some mental formula or plan of organization of the world. “…any such arrangement would be quite impracticable unless and until the actual sentiments of the peoples corresponded with these systems of rational convenience: the state of the world is at present far removed from any such ideal correspondence.”
Sri Aurobindo, The Ideal of Human Unity, Part Two, Chapter 18, The Ideal Solution — A Free Grouping of Mankind, pp. 163-165