I can reconcile sapience with a "father knows best" mindset (as you put it) because people are cruel and have a hard time walking a mile in someone else's shoes. You say there would be no reduction of personhood, but how long would it take to see a person begging for money and overhear someone tell them to just sell a kidney if they're so poor? Why should I offer money to someone too proud to do whatever it takes to survive, even if that means selling organs? This does not apply to donation but could only apply when there is monetary compensation. The slope from encouraging more donations to encouraging people to die (which already happens far too frequently for the purpose of getting donations) to expecting poorer people to sell off as many organs as necessary to support themselves is incredibly slippery and incredibly steep.
I'm afraid I don't follow. Nothing you've said really reconciles the two. It seems (to me) to simply say: "I believe X, except when I don't."
Either we're sapient, or we're not. If we are, then we have certain inherent rights, particularly over our own bodies. Chief among them, I would think, is the right to use our bodies in any way we please so long as it does not interfere with the rights of others. That means we can exclude people from using our bodies (
e.g., reflected in such things as the prohibitions on rape and slavery), grant others the permission to use our bodies for specified purposes (
e.g., by granting informed consent to invasive surgical procedures to remove cancer cells), or otherwise use our bodies as we please.
Either we have those rights or we don't. If we don't, then the government is free not only to prohibit us from organ compensation, but from any other activity they wish. And, even worse, they can compel us to perform any activity they wish, including organ donation. The can implement the Organ Tax: upon your 21st birthday, you must donate a kidney under penalty of law. This whole idea that the government must step in and control us
for our own good isn't just silly, it's morally bankrupt. If we have no freedom to make bad choices, we have no freedom.
And I don't really understand what you're trying to say about personhood, I guess. What you're describing happens every day. People tell beggars to get a job all the time. And, yet, others are still charitable. Will this worsen if people can be compensated for their organs? And does personhood really play a part in this? Do these people lose their personhood when people tell them to get a job? If so, and if we use organ sale prohibitions as a guide, wouldn't the next step be to prohibit compensation for everything? I guess what I'm getting at is this: what makes compensation for organ donations so intrinsically different that we have to set up new rules to infringe on fundamental liberties?
At any rate, this (new) argument you've posed is one about poverty, not about liberty. But prohibiting the sale of organs does nothing to alleviate that problem. Indeed, it makes it worse by limiting the options of the poor. It's certainly no more reasonable than prohibiting all high-risk jobs. The poor often find themselves in military service or working in mines, for example, and their compensation is typically more than they would receive doing low-risk jobs. But doesn't mean such compensation is inherently wrong, does it? Because the poor are more often to fill those jobs, should the jobs be prohibited? People wouldn't tell the homeless they should join the army or work the coal mine (which, according to my understanding of what you're saying, would seem to imply a loss of personhood).
So what does the prohibition really accomplish? More people will suffer and die because they can't get a needed organ. The poor will still be poor, but have fewer means of escaping their situation. It would be wonderful if those desperate situations didn't exist, but the prohibition does nothing to help that problem. Instead, it just traps them there. But don't worry, it's "for their own good." I'm sure Grindelwald would be proud.
Step softly; a dream lies buried here.