>>126
Here's a unique trait: he called himself Tuvix and pleaded for his life, which neither Neelix nor Tuvok did -- if only because they never had reason to. You seem hell-bent on defining personhood in terms of what you think qualifies as "sufficiently unique" to an external observer, instead of, you know, the needs, wants and opinions of the actual person.
My clone example wasn't meant to give you a reason to say "but that's not exactly the same thing" but to make you think about how your criterion of "no unique trait" could be applied in other situations and would be equally invalid. Sci-fi clone rules often give us clones that aren't just genetically identical, but with the original's memories too (ENT had an episode like that) -- does that change anything?
Is the "separate organism" thing what matters to you? Let's say the transporter accident had resulted in Tuvix being created *without* removing Tuvok and Neelix from the equation (a la Thomas Riker). Does Tuvix suddenly become a person with rights *then*? Why? He's the same guy, certainly from his own perspective. At *best* you could say he now has more opportunity to distinguish himself, but that's not a given. We could still separate him into new copies of Tuvok and Neelix -- would *that* now be bad because Tuvok and Neelix are still there, so *now* we are creating people "without unique traits"? But doesn't that mean we implicitly acknowledge that Tuvix is something new? It seems very odd to define the rights of Tuvix either in terms of whether Tuvok and Neelix are around, or whether the guy can suddenly play the piano.
It's one thing to say "eliminating Tuvix was justified because we wanted to get Tuvok and Neelix back and we didn't think Tuvix was all that worthy". It's quite another to say "Tuvix was never a person in the first place so it's not killing anyone". The latter might make sense superficially from a story perspective, but I don't see how you can consistently argue it without getting into some very unfortunate conclusions about who qualifies as a person with rights.
I guess we're lucky this is one of those sci-fi hypotheticals that's not likely to crop up irl, so the outcome of the discussion hopefully doesn't matter.