How would the government know whether the liver A for patient B came from a legitimate donor, some unfortunate homeless person within our country who was robbed of his liver against his will, or from some foreign national who lives in one of those totalitarian and/or lawless countries where human life isn't worth much ?
If it didn't come from a legitimate donor, either the doctor has to explain why he didn't say who the donor was, why the donor doesn't know about it, or why the "donor" still has a whole liver.
As for the foreign country, just don't accept organs shipped across national lines if the other nation doesn't check the stuff. I suspect it's a bad idea to ship organs across national lines anyway, as opposed to just shipping the donor, but I don't really know all that much about how organ donation works.
Would it be worthwhile to shorten someone's life by, say, 10 years (due to their loss of a kidney), in order to grant someone else 5 extra years of life (by using that kidney) ?
No, but I'm willing to bet that's not what the ratio will be. If losing an organ hurt you more than it helped the person getting it, nobody would ever consider donating them.
Edit:
Furthermore, let's say that people could sell their organs after they die -- by proxy, presumably -- as per your scenario above. Doesn't this create a powerful incentive for unscrupulous agents to speed their demise ?
You mean their next of kin? I don't see how it's much more of an incentive than it would be to kill them just for the inheritance. Also, I suspect that the health insurance company would normally take the money, since most people aren't going to be in a position to donate their organs and people tend to be loss-averse.
Or is the convention against discussing politics here silly?
I propose a test. I'm going to try to lay down some rules on voting on comments for the test here (not that I can force anybody to abide by them):
1.) Top-level comments should introduce arguments (or ridicule me and/or this test); responses should be responses to those arguments.
2.) Upvote and downvote based on whether or not you find an argument convincing in the context in which it was raised. This means if it's a good argument against the argument it is responding to, not whether or not there's a good/obvious counterargument to it; if you have a good counterargument, raise it. If it's a convincing argument, and the counterargument is also convincing, upvote both. If both arguments are unconvincing, downvote both.
3.) Try not to downvote particular comments excessively, if they're legitimate lines of argument. A faulty line of argument provides opportunity for rebuttal, and so for our test has value even then; that is, I want some faulty lines of argument here. If you disagree, please downvote me, instead of the faulty comments, because this post is what you want less of, not those comments. This necessarily implies, for balance, that we not excessively upvote comments. I'd suggest fairly arbitrary limits of 3/-3?
Edit: 4.) A single argument per comment would be ideal; as MixedNuts points out here, it's otherwise hard to distinguish between one good and one bad argument, which makes the upvoting/downvoting difficult to evaluate. (My apologies about missing this, folks.)
I'm going to try really hard not to get personally involved, except to lay down a leading comment posing an argument against abortion, a position I don't hold, for the record. The core of the argument isn't disingenuous, and I hold that this argument is true, it just doesn't lead to my opposing abortion. I do not hold the moral axiom by which I extend the basic argument to argue against abortion, however; I'm playing the devil's advocate to try to help me from getting sucked into the argument while providing an initial point of discussion.
Which leads me to the next point: If you see a hole in an argument, even if it's an argument for a perspective you agree with, poke through it. The goal is to see whether we can have a constructive political argument here.
The fact that this is a test, and known to be a test, means this isn't a blind study. Uh, try to act as if you're not being tested?
After it's gone on a little while, if this post hasn't been hopelessly downvoted and ridiculed (and thus the premise and test discarded as undesirable to begin with), we can put up a poll to see whether people found the political debates helpful, not helpful, and so on.