In my opinion it's not a matter of definition, it's a matter of understanding a real type of phenomenon. That's fine, and there very well may be some issues he

In my opinion it's not a matter of definition, it's a matter of understanding a real type of phenomenon. That's fine, and there very well may be some issues here that are worth investigating that don't just involve figuring out a definition. But your specific questions, "What makes something computation", and "What is it about a physical process that means it is performing computation?", both hinge on a blurry notion of "computation" that needs to be pinned down before they can even be taken on. Because if we take the first definition of the word from Google, "The action of mathematical calculation", then the answer is pretty trivial: a physical process is performing a computation if the states of the physical system reliably map to the result of a known mathematical operation, no more, no less. Now, we may quibble over what is a useful computation, whether a computation is happening if we don't observe it, etc., and that's the kind of tightening of focus that's necessary to get any answers in these situations. Those tightenings are not implicit in the word "computation". This is a typical philosophical problem - questions like "what is consciousness?" and "what about a physical process makes it conscious?" may be answered in a straightforward manner by going to the dictionary (google (Define consciousness) -> "The state of being awake and aware of one's surroundings"), but answers along those lines reliably fail to satisfy philosophers because they don't actually mean "The state of being awake and aware of one's surroundings" when they use the word "consciousness", they're using some personal tightening of the term that carries a lot of unspecified baggage (or perhaps they'll hide this baggage in "awake" or "aware", which just shifts the issue). Arguments then ensue about the right definition of the word, the one that matches the "know it when I see it" feeling that each person involved has about it, and little progress is made because nothing is pinned down concretely enough to actually discuss.