To Rabindranath Tagore, the very concept of Nation was ill-founded and based in greed of material prosperity. A Nation, to him, was that aspect which a whole population assumes when organized for mechanical purpose. By mechanical purpose must be understood material purpose, which Tagore referred to as ulterior. To him, society was far more superior, since it was a natural regulation of human relationships, so that men can develop ideals in cooperation with one another. He wished for a world of no Nations, but only societies. Tagore defined society as a spontaneous self-expression of man as a social being; a natural regulation of human relationships, so that men can develop ideals in cooperation with one another.
However, one need not consider material purposes ulterior. An example in point is the material purpose of a hungry man who wants to earn his daily bread. There is nothing ulterior about that. Of course, it becomes ulterior when greed sets in. It is not necessary that a natural regulation of human relationships must help develop only ideals in cooperation with one another. It is perfectly ethical for human relationships to help develop tangible material products and services, again in cooperation with one another, as long as greed is out of the equation. Material pursuits are valid pursuits of life as long as they don't tread on the life or liberty of others.
Once this is granted, it must be granted that groups of people uniting for material purposes is not ulterior either, again as long as such a unity does not tread on the life or liberty of others. There is nothing wrong for a group of people to seek material well-being. What is wrong, is for it to seek its own well-being at the cost of pushing other groups to levels of poverty and helplessness below its own levels, by taking the life or liberty of others. Thus, material pursuits become ulterior only when they cross the boundary of ethics. Within that boundary, there is ample space for a valid and ethical Nation to be defined.
British India and Britain itself were, of course, invalid and unethical Nations. The British took the life and liberty of people in this part of the world in order to feed the greed of material prosperity of the British.
But that need not bias us against the very concept of Nation, like it did seem to bias Rabindranath Tagore. It is perfectly fine for a set of people (or peoples as in the case of India) to organize themselves for the mechanical purpose of material prosperity, and call themselves a Nation. There's nothing ulterior about it as long as greed does not set in. Thus, a Nation need not be necessarily based on unethical or greedy grounds.
However - and this is very imporant - on those who define the Nation rests the burden of ensuring that there is no compromise of life or liberty not just outside, but even inside it. If this ensuring is not done with due diligence, the Nation becomes invalid and unethical. It is only if this ensuring is not done with due diligence, that a Nation becomes tyrannical and unjust - the Nation which Tagore so hated.
The first symptom of such tyranny and injustice is the disregard and disrespect for diversity; the second is the foolish belief that unity can be achieved by forced juxtaposition of the language, culture, religious beliefs, and whims and fancies of one people on every other; and the third is the legalization of an unfair advantage given to selected people or peoples in education and employment (even if it is unintentional). These symptoms are already seen in India.
The first step towards curing India of this disease is to convert India into a Federation of Linguistic States equal in all respects, and in whom the very same principle of respect for diversity and upholding of life and liberty is in turn enshrined. This is the India of our dreams. Such an Indian Nation is free from the ills of the greedy Nation which Rabindranath Tagore so hated. It is not difficult to build such an Indian Nation. We just need to make an attempt to build it.