Monday, June 04, 2007

Kidney Exchange for Central Planners

One of my students sent me this article about Tuomas Sandholm, a Carnegie Mellon computer scientist who is using game theory to facilitate kidney donations. The article reports on the increasing popularity of paired kidney exchanges, “in which one kidney patient's relative or friend will donate an organ to another patient, whose own relative or friend will donate his organ to the first patient.” Such exchanges are limited by the fact that it’s not always easy to find patient pairs with relatives or friends who happen to be compatible matches.

Sandholm’s contribution was, first, to recognize the possibility of multi-party exchanges (e.g., A donates to B’s relative, B donates to C’s relative, and C donates to A’s relative); and second, to devise a computer algorithm that will allow multi-party exchanges with (almost?) any number of parties (e.g., A donates to B’s relative, B donates to C’s relative, C donates to D’s relative, ... , and Z donates to A’s relative).

Now, this is all great, and Sandholm is doing admirable work. But as I read the article, I couldn’t help lamenting that our current system of organ donation has reduced us to the use of barter. What Sandholm has done, quite simply, is to increase the efficiency of barter. Using his algorithm, we could presumably arrange other kinds of transactions as well: a baker gives some bread to a doctor, who provides medical care to a carpenter, who fixes a cabinet for the baker. Fortunately, we don’t need Sandstrom’s method for that, because we already have a venerable institution that coordinates these magnificently complex trades with remarkable efficiency and without the need for central organization. We call it money. Unfortunately, this mechanism has been outlawed for human organs, thereby forcing us to rely on the far more primitive mechanism of barter.


Kidney Bean said...

Wouldn't you agree that YOUR kidney is more valuable than a Picasso painting? I think your valuation is correct. I doubt nature provided us with 2 kidneys so that we could sell one for a tidy profit. If that were the case then nature would have given us at least three kidneys so we'd have more than one to sell. I don't think capitalist considerations are involved in Darwinian evolution, maybe in a human misapplication call Social Darwinism.

What if I want to sell both my kidneys? Then, I could live on a dialysis machine for a while until all my other vital organs fail, and I die. I know that the quality and lenghth of my life will be shortened greatly. Personally, I'd like the proceeds of my sale to go to the Institute for Humane Studies to support further ethical studies on the issue. My dead body can be sent whereever.

Suicide is so senseless, but not necessarily so, if the IHS is well funded.

Glen Whitman said...

Kidney Bean -- are you serious? Because your response is so silly as to be laughable.

No, I don't think my kidney is more valuable than a Picasso painting. Picasso paintings are worth tens of millions of dollars. I would happily sell a kidney for $10 million.

And it's not just me. Empirical fact demonstrates that many people will sell their kidneys for much less than that -- usually somewhere in the low thousands.

What if you sold both kidneys? Wait, I thought you just said you thought even one kidney was worth more than a Picasso painting! Therefore, nobody will ever offer you enough to gain your consent. But let's say they do. Then you should have more than enough money to pay for your dialysis and/or funeral. After a while, maybe you'll figure out your dumb mistake and someone will sell you a kidney. If not, well, I guess that is Darwinism at work.