Well that's kind of the point, you really couldn't, outside the copy's insistence that they were the original. But that means that insisting externally that they're not "really" who they say they are is just as unprovable.
There's futurists who take the maximalist position that eventually we'll either have predictive technology capable of re-tracing the history of every extant particle in the observable universe and thus recreating the past in perfect detail, or that we'll make some breakthrough in physics and cosmology that makes direct observation of the past possible.
I don't really know if I buy either of those propositions, but either way telling a recreation of a past individual that they're not really that individual despite their insistence is trying to disprove a negative. I've heard people bring up the Chinese Room in regards to this sometimes, but that also applies to literally every living being capable of communicating with you.
Well that's kind of the point, you really couldn't, outside the copy's insistence that they were the original. But that means that insisting externally that they're not "really" who they say they are is just as unprovable.
There's futurists who take the maximalist position that eventually we'll either have predictive technology capable of re-tracing the history of every extant particle in the observable universe and thus recreating the past in perfect detail, or that we'll make some breakthrough in physics and cosmology that makes direct observation of the past possible.
I don't really know if I buy either of those propositions, but either way telling a recreation of a past individual that they're not really that individual despite their insistence is trying to disprove a negative. I've heard people bring up the Chinese Room in regards to this sometimes, but that also applies to literally every living being capable of communicating with you.