Part of the problem here might be that Oerter is not carefully distinguishing the following two claims:
(1) There just is no fact of the matter, period, about what function a system is computing.
(2) The physical properties of a system by themselves don’t suffice to determine what function it is computing.
Oerter sometimes writes as if what Ross is claiming is (1), but that is not correct. Ross is not denying, for example, that your pocket calculator is really adding rather than “quadding” (to allude to Kripke’s example). He is saying that the physical facts about the machine by themselves do not suffice to determine this. Something more is needed (in this case, the intentions of the designers and users of the calculator).
What exactly does Ross claim? Here is Ross from his paper:
Adding is not a sequence of outputs; it is summing; whereas if the process were
quadding, all its outputs would be quadditions, whether or not they differed in quantity from additions (before a differentiating point shows up to make the outputs diverge from sums).
For any outputs to be sums, the machine has to add. But the indeterminacy among incompossible functions is to be found in each single case, and therefore in every case. Thus, the machine never adds.
Extending the outputs, even to infinity, is unavailing. If the machine is not really adding in the single case, no matter how many actual outputs seem "right," say, for all even numbers taken pairwise (see the qualifying comments in notes 7 and 10 about incoherent totalities), had all relevant cases been included, there would have been nonsums. Kripke drew a skeptical conclusion from such facts, that it is indeterminate which function the machine satisfies, and thus "there is no fact of the matter" as to whether it adds or not. He ought to conclude, instead, that it is not adding; that if it is indeterminate (physically and logically, not just epistemically) which function is realized among incompossible functions, none of them is. That follows from the logical requirement, for each such function, that any realization of it must be of it and not of an incompossible one. [emphasis added]Ross is quite clear: he is not saying (2) at all. Neither is he saying (1). He is saying something stronger than either (1) or (2): the machine does not add - period. It is not that the physical properties of the system alone don't determine what function it is computing, the system isn't actually computing any function at all. "... if it is indeterminate (physically and logically, not just epistemically) which function is realized among incompossible functions, none of them is."
I just don't see how Feser can write "Ross is not denying, for example, that your pocket calculator is really adding rather than “quadding”..." for that is exactly what Ross is denying.
It is this denial I had in mind when I said Ross couldn't apply the same reasoning to Hilda without denying that Hilda adds, too. But rather than re-visit that argument I will wait for the professor to (I hope) clarify.