Earlier quoted context omitted.
We know the brain is doing something - if you don't want to call it computation, then you might as well call it magic.
There are other possibilities. For example, there can be an immaterial mind that operates as a halting oracle and interfaces with the world through the brain. Halting oracles are well defined, and we can empirically test for their existence. So, no reason why we have to assume everything humans do is reducible to some sort of automata. The only reason we make the assumption is because of prior materialistic commitmen…
Also, personally what my mind is doing doesn't feel like it's invoking an oracle for my problem solving. Generally when the search space for a problem that I'm solving increases I experience the kinds of blowups in the difficulty that would arise from me following an algorithm. Now, not everybody is the same. Do you feel like your problem solving calls an oracle?