From an all-knowing God's perspective, any claim with pretensions to eternal validity that a human being might make would tempt the comment, "Of course, you would say that, with your history, and your experiences and the history of the universe behind you pushing and pulling you to say just that. History and causality are sufficient to explain just why you would say that."
Ok, so strict determinism. Big whoop. Consider this: if the conditions, the soil as it were, from which this view of something arises were constituted a little differently, wouldn't the perspective, one's view and belief on the matter at hand be different? All perspectives are equally contingent, equally haphazard. This includes Nietzsche's perspectivism as well.
Naively considered, Nietzsche's perspectivism is self-refuting. But let's look at perspectivism a little more closely. An analogy from algebra and arithmetic. In order to solve an equation it is necessary to manipulate the form of the equation in order to put it into a form whose solution is relatively straightforward. Simplification is achieved by adding, subtracting, and multiplying quantities in a way that respects the equal sign of the equation. Analogously, the concepts of perspective and perspectivism are an equation to be simplified so that solutions and observations are straightforward.
Nietzsche's perspectivism looks like it makes an assertion with identifiable content and truth about ideas and human cognitive processes. If, however, the content is an assertion of a lack and of limitations of perspectives, namely that there are other perspectives which are mutually irreconcilable, It asserts a negative. It tells us something about human cognitive processes in the same way that denials of the existence of unicorns tells us something about the taxonomy of animals. If, however, there are bureaucracies and institutions that have made the existence of unicorns central to their continued existence, then denials of unicorns become a direct challenge to the existence of those unicorn-centric bureaucracies and institutions by calling attention
to the limits of unicorn-centrism.
At this point perspectivism becomes indistinguishable from popular conceptions of relativism and what Nietzsche called nihilism. All perspectives become equally valid. There are no standards by which ideas, perspectives, and views may be ranked and organized. This is true in that value is not a quality of things. I would like to point out that as disconcerting as this may be, that there is a way out. Even if all views and ideas have the same relative value considered without regard to persons holding those views and ideas: namely zero, these ideas and perspectives do not all have the same value for me. Preference for one perspective over another is rooted in flesh and blood. This includes truth as well.
Perspectivism challenges traditional metaphysical claims to transcendent and knowledge of eternity and the like. An unlikely philosopher and later contemporary provides a surprisingly useful view on this whole matter: the early Wittgenstein, specifically his Tractatus Logico-Philosophicus. Consider the following:
That the world is my world, shows itself in the fact that the limits of the language (the language which I understand) mean the limits of my world.
. It's not the quote that I remembered. Oh well. What I remembered is the following:
Our life is endless in the way that our visual field is without limit.
See what I wrote here. Just do a search in the google search box to the left of the phrase "last moment of innocence". "The last moment of innocence" is a specific instance of a the more general insight that the boundaries of perspectives are only reluctantly acknowledged in the vast majority of cases.