This question came up for me when I began considering metaphysical realism and metaphysical idealism.
Realists claim that there exists an objective world independent of consciousness, though we only have indirect access to it via our sense perceptions. On the other hand, idealists essentially claim that nothing can be known outside of consciousness and therefore positing an entire world independent of consciousness is un-parsimonious and unjustifiable. Therefore, there is no world outside of consciousness as a category. It may very well be that there is an objective consciousness beyond our personal consciousness (objective idealism), but idealists think that claiming an entire (physical) world exists beyond consciousness is wrong.
Although I am sympathetic to both realism and idealism in some ways, it seems as though both positions are unverifiable. For the realist, the idealist makes a very powerful point that we cannot escape consciousness and subjective experience to go beyond it and verify that there indeed is a world independent of consciousness. However, for the idealist, the realist can claim that just because we cannot go beyond consciousness to verify the existence of a world independent of it does not necessarily mean that it isn’t there.
Is this dilemma between realism and idealism ultimately irresolvable? In other words, how could we ever possibly know which of them is true? Or do we just have to use principles such as Occam’s Razor and parsimony to conclude that one is at least more likely to be true over the other?
