There are different levels of argument depending on the precision of the definition of the concepts in play, which is unhelpful in general but also unavoidable.

There are different levels of argument depending on the precision of the definition of the concepts in play, which is unhelpful in general but also unavoidable. I think that the folk definition of computation is so wide and vague that almost any physical process can be characterized as a computation in that sense. So brains (being physical) must be (folk) computers. The problem is that this doesn't get us anywhere because there are lots of equivalences and for practical purposes in there and what we really need is a characterization of the brain as it operates rather than what that operation might be modeled as. As Searle says, you can simulate the processes of digestion but that doesn't mean that you have an artificial stomach that can turn food to energy.