(One UPDATE below...)
Below Gene questioned the typical libertarian endorsement of self-ownership:
I've always thought the concept of "self-ownership," so loved by many libertarians, is a little screwy: Man is not a good he owns, he is himself. To the common comeback, "If you don't own yourself, then who does?" my answer has been, "No one, just like no one owns arithmetic or the night sky."
Insofar as he goes, I agree with Gene. However, all it takes is a simple change of terminology to body-ownership, and then the standard libertarian view is fine. Is that all you're saying, Gene?
If not--i.e., if you're really disputing that it makes sense to view human bodies as being objects of ownership--then what were slave auctions all about? Traders never grabbed the night sky and sold it to plantation owners.
Also, the more I think about it, the less coherent I find the view that rejects the ability of someone to sell his body to another. What's especially odd is that Rothbardians believe that a victim can rightfully enslave his aggressor, at least until the crime is rectified. So if John can own Jim's body because Jim shot John in the leg, then why can't John own Jim's body because Jim signed a contract in exchange for money?
Whatever metaphysical objections you might have--"what if Jim later regrets his decision?"--don't work when Jim was an aggressor. So why do they work when he isn't an aggressor? If Jim doesn't like his body being owned by John, he shouldn't have shot him. Or, he shouldn't have signed the contract and accepted the $200,000 that he blew in Vegas.
In talking with (the young) Dick Clark, we clarified one of the stickling points on this issue. I said, "Rothbard's right, you can't alienate your will. But you're selling your body, not your will." To this Dick said, "But your body doesn't work without your mental controls."
I think this is the crux of the dispute. In order for someone to be a productive slave, he has to have his heart and soul in it.
Or does he? After all, I think the vast majority of slaves had their body ownership stolen. Their (unrightful) owners figured out ways to motivate them to order their "own" bodies to do the tasks that the (unrightful) owners wanted.
I think we need to remind ourselves what it means to be an owner. To paraphrase Kinsella, it means that when you and someone else have a disagreement on how a scare resource should be used, you are "in the right."
Let me give some more examples to illustrate that libertarians are wrong for conflating mental control with body ownership.
(1) Suppose you have telekinetic powers and can control "my" car just by thinking. Does that mean you are necessarily the owner of "my" car? No, of course not. It makes perfect sense to say I still own the car, and I can use my vastly inefficient means of controlling it. If you use your superior mental influence to have it perform the tasks you desire, then you just stole from me.
(2) Suppose you have a terminal illness and agree that your estate will get $1 million, in exchange for which you will be killed and your organs will be sold on various markets. After you accept the $1 million, I don't see why the title to your body is still in your hands. It's gone. (Of course in a civilized society they would probably have standard "backout" clauses in these contracts, but that's a practical detail; it's not a bedrock principle.)
(3) Suppose you have a huge gambling debt. An eccentric millionaire says he'll pay off your debts, but you agree to be his prey in a hunt on his estate. If you can reach the green zone, then he gives you back your freedom. So long as this contract is truly voluntary, how does it violate Walter Blockian precepts? Isn't this very similar to Block's "Murder Park"?