Over at talkingphilosophy blog Jeff Mason has an elegant essay on metaphysics that takes the Kantian view that the physical sciences are the source of all knowledge and everything else is mere speculation. My problem with this essay, and Kant’s critique, is that they are the worst examples of the very thing that they are complaining about—making, as they do, grandiose excessively-general statements about the nature of reality that are quite immune from empirical or logical examination, the most extravagant metaphysical conceit of them all. The genre really should be called metametaphysics as it installs itself as the last arbiter on truth and preemptively disqualifies, tout court, anything that could offer an alternative to its dogmatically positivistic understanding of reality.
Good scholarship, good philosophy, common sense requires that each claim to structure reality, and there are many, including the positivistic and various religious traditions be examined on its own merits to make sure it does what it says on the tin. It is unlikely that only one perspective is coherent and useful—we should expect to find more than one, but it is truly pointless to expect to be able to assess one of these philosophies using the framework of another and find anything useful. That will just lead to the predictable conclusion that the best way of seeking the kind of knowledge that system A is intended to deliver is to use system A.
It is my experience that the positivists are so locked into their way of understanding reality that they, quite literally, can’t comprehend any other way of thinking, or often conceive it is possible that any other way could provide access to knowledge (that couldn’t be acquired more directly with their system). Such is the narrow world of the fundamentalist.