You choose topic, I choose position.

A rebuttal works when it shows that the opposing position with regard to the proposition fails I am not sure that he takes me to be stating a general point or a point about mathematics. It is usual to show that an apparent phenomena can be represented mathematically as means of having a loo at it, it is why physics makes such ample use of maths. I am arguing in terms of a more general point,; that functional ascriptions are under determined by evidence. So for any historical list of behaviours in response to sets of conditions. I am arguing that there remain a host of alternate functional ascriptions equally warranted by the historical evidence. Aeroplanes trucks space rocket malfunction, for any plane that has not been grounded there is no evidence of a serious fault that might cause the aeroplane to fail, it is constrained not to fail. Any theory that a given plane will not crash based on the laws of physics and physical evidence of behaviour planes may be said to warrant the idea that it will not malfunction. But the term malfunction just means that it will not function in accordance with its prescribed function. It will instead do something else that is it will function differently. Again we have a case of under determination by evidence, physical evidence is not enough to exclude all aberrant behaviours. Intentionally x functions if it does what it is intended to do. So we can write a use/ case spec for an entity and claim x has a functionality F because F captures what it is we intend x to do. But how are we to express our intentions but via some use case. In the case of a person we may say that she intends perform a task spec or function if she intends to order her behaviour in terms of it that function. Whether her knowledge of the behaviour required be in a manual or internalised though training we need an account of what intention she has. My contention is that for any Intensions (I do not mean intentions) we ascribe to someone on the basis of the evidence available the evidence available equally justifies the ascription of variant and incompatible intentions. More genuinely any scheme of ascribing a rule-based interpretation of function such that a function may be ascribed to the world as a whole.( or to the Universe as pro prefers) will ascribe functionality to subsets of that Universe which are under determined by the evidence available. As a parting point. The world's function is to do exactly what it does if we accept the Panglossian argument. It is to follow a set of rules that are established by long and arduous study of the phenomena of the world in the pursuit of a theory of everything. Which put in more simplest terms is the world's function is to do what it does and become whatever it becomes. And the function of everything in the Universe is to play its part in what it does. Panglossianism was formulated at the time of the Heyday of Newtonian physics since Newtonian physics was false as a scientific theory the Panglossian was historically wrong. It is not the function of the world to function by Newtonian physics despite it being the case that the canon of scientific evidence at the time fully supported the attribution of that function. Furthermore, there seems something inherently wrong in defining function solely in terms of observed phenomena. I would suggest that Quantum physics is as likely to be falsified in its present form and supplanted by another model. We cannot exclude the possibility that an incommensurate theory equally warranted by the observation of phenomena will not supplant it. In which case attributions of function in terms of quantum physics will also fall by the wayside. The Panglossian argument failing again. The Panglossian argument was used by Voltaire as a joke, an illustration of apparently sensible words being put together which on the one hand is irrefutable but strikes us as having some weight. Saying that the world functions in doing what it already does and then tagging on perfection as a property of a physical thing is a recipe for fallacy. An irrefutable proposition can have no material consequences. In the sense in which the Panglossian argument is used for arguing that we have no duty to change the world, it is wrong because it is flummery; empty argument standing in the garb of the meaningful.