That doesn't mean we have to give up on understanding the mechanism. Nor does it mean we shouldn't try to find out if it isn't a sufficient explanation. But calling it an unsupported belief system goes a bit far. It certainly isn't proven scientific theory. And there is room for it to be wrong. But there are good scientific principles behind this belief.
Intelligence and consciousness are two of the things we don't understand.
I agree it would be going too far to call it an unsupported belief system. I don't think I implied that it's unsupported, but it is a belief system. My point is that even with support, the underlying, unproven or unprovable assumptions should not be glossed over.
I'm skeptical that we have a mechanistic explanation of intelligence. I think we have sensible-but-unproven hypotheses, partially supported by observations, for how intelligence might evolve/arise. There's a lot of hand-waving between mechanistic principles and an outcome of general intelligence. One can imagine Occam's razor applying, if the hand-waving eventually resolves to something coherent. Until then, it's a combination of good science and fantasy.
Intelligence is just one of many human experiences that are believed/assumed to have mechanistic explanations. We should be careful to recognize the assumptions, however sound they may seem, and not turn them into dogma.
I feel very weird about this too.
This de facto assumption that organisms are mechanisms first, that "higher-order" experiences we are familiar with as humans are at best "emergent" from these mechanisms--I wish people would understand that this is fundamentally as much a belief system, an article of faith, as the many alternatives are.
Saying this doesn't imply that every belief system is equally valuable or scientifically verifiable. But I think it's important to recognize one's axioms and/or biases.
The mechanistic view is certainly compelling and has the appearance of being all-encompassing.
Its all-encompassing appearance may actually be an artifact of how used to the story we've grown. A clockwork universe. We know that one by heart, whether we're scientists or not. We can apply that template to anything, and set about exploring (or reading about) the mechanisms. The fact that there are mechanisms everywhere doesn't prove that mechanism is all there is. That last part is an implicit belief system, a hidden article of faith, and that's how you get Descartes vivisecting dogs, and conscious experience necessarily (as though no other possibility could exist) having to be an "emergent" property.