I think if you want to make a statement such as "Every electron has its own (self-)identity or "haecceity" simply by being numerically different from all other electrons: where there are two or more electrons, there are two or more numerically different electrons. Simple as that!" you'd have to describe an experiment whose results can only be explained if that statement is true.
This is why I suggested earlier that purely ontological questions about how things "really are" such as "are electrons really identical?" serve no purpose and just lead to confusion unless they're tied to what can be observed.
So is Consul saying in effect that if you can count things, including electrons, then they are discrete entities? From what Consul says, I gather that my original question is a question about epistemology: how we can know anything.
Steve, are you agreeing that questions about how things "really are" are epistemological questions, and not ontological questions at all?
Earlier, Steve, you mentioned how a physicist can measure a double decker bus. Is it the case that while I , who am not a physicist, can measure a double decker bus I cannot measure an electron because only physicists who have special measuring techniques can measure electrons? This is an epistomological question, would you say? I mean how we differentiate entities is a separate question from "is any entity, ranging from a double decker bus to an electron, a real entity?"
So, Steve, are you claiming that scientific realism is the only ontological stance that serves any useful purpose? If so, I agree. What is the difference if any between scientific realism and logical positivism?