Say a machine is invented that allows one individual to transfer years-of-life to another individual. Should people be allowed to buy and sell their years-of-life or should these exchanges be outlawed?

If your answer is yes, picture the cults that would arise with the sole purpose of breeding and brainwashing people so that they give life-years to their now immortal Leader.

If you’re answer is no, then does the morality of kidney exchanges hinge on the evidence that donating a kidney doesn’t lower life expectancy? As far as I know randomized studies on this have never been done, and the selection bias and unobservables here seems potentially insurmountable. If these results were overturned by a  randomized trial, how many kidney exchange supporters switch positions?

I do support kidney exchanges, but I also don’t have good answers to these questions.