- "there is every reason to believe that a human brain is a machine"
Given what evidence?
- Platonism died for mathematicians some centuries ago, and simply looks silly.
And yet Frege and Gödel, two of the most accomplished mathematicians of the past century, could be described as Platonists. Clearly this isn't a closed question.
https://en.wikipedia.org/wiki/Philosophy_of_mathematics#Plat...
https://plato.stanford.edu/entries/platonism-mathematics/
Regarding digestion: if the Turing Test is determining whether a computer is thinking like a human being, then focusing only on input and output, and not the 'being', sort of misses the entire point. Remember that Searle's Chinese Room is primarily a criticism of the Turing Test.
As always, the truth is: it's more complicated than it seems.