It was not Schopenhauer that originated this concept but he borrowed it from Hinduism through Upnisads.
It is slightly different from FC’s ontology of self valuing, for the simple reason that FC’s concept of self valuing is very subjective, while Hinduism visualizes will as objective also.
FC’s N says will to power but Hinduism says power to will. It is not merely a linguistic issue but the question of deciding the basic nature of the will.
FC says - Get power through willingness. It is a straight line and infinite process, without any control.
Hinduism says - Get control on your willlingness. Do not be its slave but master it.
And, that changes all. And, that is precisely the difference between N and Buddha. One says acuumulate as much as you can while the other says let go as much as you can. One says change the ambient according to you, while the other says change yourself according to the ambient.
Secondly, at the metaphysical level, there cannot be anyting but will only. It is one of those concepts that cannot be logically challenged ( without an alternative, as you always put it).
For a will to exist, firstly and lastly too, it must have will to exist. Then, this will would have two alternatives only. First alternative would be to maintain the status quo, means there would be nothing else except the will to exist only. It does not want any change but just to remain in existence. This is the state of perfect unentropy; The Eternity (nothing changes).
The second option would be to berak away from the status quo and will for something more than mere existence. There cannot be any third option. So, as soon as the will wills to change, entropy takes a start. From hereon, RM can take the baton and can explain the formation of small and large particles from the metaphysical concept of will to change. Different particles would be formed but still all that manifestation of this universe is nothing but trandformed will to change into different shapes.
That is why all religions say that this world is not real but illusion. That is technically true but it is also true that it is for real as far as we are in it. To move out from it ( realize and eliminate all wills except to exist) is enlightenment.
Schopenhauer had only a broad idea of this subtle concept and was not gone deep enough. He was not wrong but incomplete.
Thirdly, comes the question of consciousness. I do not think Schopenhauer got it in its entirety, though he had some glimples of it for sure. Without taking a saperate feeling entity other pure will, ontology cannot be completed. It cannot explain what we call life. If complexity was the only cause of consciousness, this universe would have been evolved differently. Big stars, white dwarfs and black holes would have been evolved as life forms instead of small manifestaions like humans, animals or even ameabas. Logically, odds are in the favor of that but that did not happened. That is what pursuaded ancient thinkers to look to alternative explanations.
To create life, we need something extra than mere will to change (complexity). That is why i repeatedly said that there cannot be any AI ever. A will cannot feel by itself. A large planet like earth is also a manifestation of will and so the humans. But, we feel while planets cannot. We need something extra to complete the sequence.
And James, it is not mere a theory. It can be varifed at personal level.
with love,
sanjay