R Scott Bakker advances the case for an ultra-modern, neurologically-informed skepticism:
The question [Blind Brain Theory] raises — the Kantian question, in fact—is simply whether the way humans are functionally constructed to track our own states allows us to track the way humans are functionally constructed to track our own states. Just how is our capacity to know ourselves and others biologically constrained? The evidence that we are so constrained is nothing short of massive. We are not, for instance, functionally constructed to track our functional construction vis a vis, say, vision, absent scientific research. The whole of cognitive science, in fact, testifies to our inability to track our functional construction — the indispensability of taking an empirical approach. Why then, should we presume we possess the functional werewithal to intuit our functional makeup in any regard, let alone that of social cognition? This is the Kantian question because it forces us to see our intuitions regarding social cognition as artifacts of the limits of social cognition — to eschew metacognitive dogmatism.
As a quotable bonus, the conclusion to the David Roden article just cited:
Nor (given our lack of any transcendental grasp of agency) are we entitled to reflect on the ethical status of very strange posthumans. We have no future-proof grasp of how strange posthumans might be, so we lack any basis for adjudicating the moral status of such beings. We may buy into a parochial humanism which accords humans subjects a level of moral consideration that is greater than the nonhuman creatures we know about. But this does not entail that there are not morally considerable states of being in [Posthuman Possibility Space] of which we are currently unaware which have little in common with the modes of being accessible to current humans. If posthuman politics is anthropologically unbounded, in this way, then any ethical assessment of the posthuman must follow on its historical emergence. If we want to do serious posthuman ethics, we need to make posthumans or become posthuman.
ADDED: Dark Lord possibility space.