Two points, firstly, the negative side and discrimination towards those we perceive to be outside our group. To compensate for this through what is sometimes termed “positive discrimination,” I still see as discrimination.
Yeah, I agree. I think we can do better than engaging in identity politics discrimination with transhumanism/posthumanism.
Secondly, to address your final point and one I see as crucial. You say “I think we should very clearly define what a more perfect human would look like, and then work towards that.” There is a fundamental problem here and it’s a big one, as I said previously “perfection” is subjective. So how do we define perfection and who is the “we” who gets to decide what constitutes perfection. I’m guessing that if you were to ask a large group of people from any walk of life as to what their idea of a perfect human would be you would get varied answers. I personally can’t think on an objective definition and I have been unable to find one, so if perfection cannot be objectively defined then striving for it is impossible.
You originally said "more perfect" and I don't think that is subjective to the degree you're mentioning it.
If you asked a big group of people, they will want to be more physically attractive, intelligent and stronger (especially for men). That's really enough to show there is some degree of objectivity for human perfection. But I'm not interested in transhumanism that makes people more of those things because humans will simply adapt to those things and become bored/unsatisfied again.
What trends closer to perfection is a human that isn't burdened with a psychology that is insatiable. THAT is a fence to swing for. Imagine not needing to work, work out, drive through peak hour, deal with tricky conversations etc. in order to grind out some meaning in life? All those pesky, annoying tasks that generate meaning in our lives could be bypassed if that type of meaning were not required, or if a post-human replacement for meaning (something with stronger affect) were genetically hardwired into our genomes, of which could be generated in a more efficient way.
Or how about a human psychology that doesn't adapt to drug usage, and thus you could live in a constant state of bliss, as if you'd taken heroin and cocaine for the first time AND that effect never subsides. Compare that to what we currently have, and there's no doubt in a reasonable mind that a constant state of bliss is superior to what is normal now.
Those seem to be "more perfect" than what we currently have. I think if those were pitched to humans, that would be your "we" deciding to strive towards these goals.
There is another factor, assuming there is an agreement on what constitutes perfection, then by the fact that it is perfect, it would be applied to everyone, so there would be no individuals and we would become a collective. As to whether that would be considered beneficial or detrimental is subject to opinion, but I do have a feeling that those in power who would be implementing this perfection, would probably prefer to remain imperfect.
I think those who fully embrace transhumanism (especially posthumanism) would simply make those "imperfect" obsolete, and thus unable to remain in power. Super smart transhumans with 3500 I.Q. (relative to humans) would be too smart for any human trickery.
It is strange to think about how a posthuman would wield power. We know that humans are easily corrupted by it (although, not all the time), but a posthuman? Or even transhuman? I think that's where some issues may manifest.