JD WALTERS SAID:
One question I'm interested in is the dialectic between empirical evidence and metaphysics. Is it meaningful to speak of empirical constraints on metaphysical views? Or are all empirical considerations entirely relative to one’s paradigm?
I guess that depends on what you think our paradigm should be able to do. If you think our paradigm should preserve the basic structure of our experience and our impressions with as little adjustment as possible, then you’ll favor a metaphysical view that does that.
If, on the other hand, simplicity is your criterion, then you may be prepared to sacrifice more common sense, properly basic beliefs as long as that streamlines your paradigm.
And, of course, something can be simpler in one respect, but more complicated in another. There may be tradeoffs.
Or if your objective is a naturalized epistemology/ontology (e.g. Quine, Dawkins, Churchlands), then you may go to great lengths to explain away appearances to the contrary.
Naïve realism is simple inasmuch as it eliminates the gap between appearance and reality. It takes the deliverance of our senses at full face-value. Does the least disruption to our immediate impressions.
Yet it’s deceptively simple. How can a mountain be objectively smaller at a distance from me, but objectively larger near you? So, to eliminate the paradoxes of naïve realism, we may switch to direct realism. That’s more disruptive to our individual impressions than naïve realism, but less disruptive to our collective impressions (i.e. many different observers).
Or take Berkeleyan idealism. That’s simple inasmuch as it eliminates the gap between appearance and reality. Eliminates the gap between primary and secondary qualities. Ontologically simple inasmuch as one substance (mind) is simpler than two (mind and matter).
Yet there’s a cost to that simplicity. It simplifies in one respect, but complicates in another. Why does the human body have so many useless parts and organs? Here physicalism and dualism have the simpler explanation. We appear to have a physical body because we really do have a physical body. As such, all these parts and organs perform real functions.
Mind you, it’s still possible to come up with a face-saving alternative. Take the brain-in-the-vat. The reason the “world” of the test-subject has this fine-grained detail is because that’s necessary to maintain the illusion of verisimilitude. So it is functional, but in a different respect. Functional to delude the test-subject into believing it’s real, so that his reactions can be studied.
But that’s a complicated explanation in its own right. It accounts for the illusion, but it also pushes the explanation back a few more steps, since you must then explain the aliens.
What about a scientific explanation of human vision? Sensible objects emit photos, which impinge on the eye. Then the brain takes over from thereon out, translating the electrochemical impulses into conscious mental imagery. Making various compensations along the way.
Yet that description is somewhat deceptive, for it charts the process from start to finish, from the outside to the inside. But, of course, a scientist can’t assume the viewpoint of an outsider to the process he describes. He doesn’t see the sensible object emitting photons which impinge on his own eye.
His understanding of the process comes at the tail end of the process, as the end-result of the process he presumes to describe. And if that’s all he’s got to go by, then he’s in no position to retrace the process. He can’t step outside himself to tell us what happens before the brain takes over, then what happens after the brain takes over. For him, it’s the brain all the way. And even the brain is not an object of direct inspection.
So where does that leave us? How much confidence should we vest in that 3rd-person description?
Well, that depends on other considerations. From a Christian standpoint, if God designed our visual system; if God put us in a visible world; if, indeed, God told us the story of how he made us, and how he made our world, then there’s far more reason to trust the prima facie evidence of our senses. We perceive the external world because there really is something out there to perceive. So it all hangs together.
If, on the other hand, you posit a blind creative process (i.e. naturalistic evolution), then maybe we’re like a bird that keeps flying into the windowpane. It can’t tell the difference between clear glass and thin air. And it lacks the mental aptitude to correct for its mistake. It keeps swinging back around and hitting the same windowpane. Bang! Bang! Bang! Until it drops in a heap of feathers.