Larissa MacFarquhar’s article on kidney donation in the July 27th New Yorker reminds us that our society remains uncomfortable about the satisfying of bodily needs by making use of other people’s bodies.

This is a good discomfort, no?  Nobody should blithely take advantage of another person, coercing him into donating his organs or making use of her for sexual pleasure without consent.  Watching Stephen Frears’s 2002 film Dirty Pretty Things leaves you appalled and angry at the kidneys-for-passports trade, as it must.  Slavery is an outrage and an offense, a rejection of the values that make ours a civilized society.   Every thinking person decries the trafficking of women for sex.   In modern society, it feels wrong when one person’s body is used to  advantage another’s body.

The exchange of money in the process seems to change the moral valences without exactly alleviating the discomfort.  That children’s families are paid for their manual labor in processing cocoa for the chocolate we eat doesn’t make the practice of child forced labor seem less heinous.  Maybe we even boycott chocolate manufacturers who use chocolate from Ivory Coast, where child labor is involved.  Taking advantage of children’s bodies disturbs us (even to the point of limiting our chocolate purchases).

Money registers differently when it comes to adult sexual exchange.  In the usual American view, there is a bright line between sexual enjoyment obtained through the use or threat of force, and the same enjoyment procured by payment but without force.   Both forcible rape and prostitution are illegal, but most people would recognize a distinct difference between the moral repugnance elicited by rape and the tinge of moral corruption carried by sexual advantage obtained by payment.

Payment introduces a legal twist to sex, too:  the law holds the man who procured sexual advantage through force to be culpable in the act of rape.  Yet, when it comes to paid sex, the legal code holds the woman who provided the sexual service accountable.  The bluenose might scorn both the sex worker and her client equally, but the law makes a distinction.

By contrast, payment makes all the difference when it comes to the use of someone else’s body for productive manual labor.  Your neighbors would be repelled if you were to use force to make a passer-by reshingle the roof of your house, and might have you arrested.  But they aren’t bothered when you hire a roofer.  Most aren’t very bothered when the roofer has some immigrant laborers do the scut work for below-minimum wage — which seems someplace in between a true fee-for-service contract (you in need of a new roof, a roofer able to build one) and slavery.  When money changes hands, it softens the moral impact of making use of someone else’s body.

But the moral flavor doesn’t disappear.  If your roofer refused to let his immigrant workers come down off the roof during a lightning storm, his meager payments to his workers would feel less important than his endangering their welfare.   In other words, onlookers would still be moved by the moral flavor involved in making use of someone else’s body.

Now for the tricky part. What about the use of others’ bodies for medical research? An article in today’s Times laments the shortage of willing bodies for testing cancer treatments.  Contemporary medical ethics presupposes a human trait called “autonomy” and requires that researchers respect this characteristic – for instance by refusing to experiment on a person unless she has signed a consent form acknowledging that she agrees to be experimented on and asserting that she understands the risks and rewards involved.

Of course, the reward system is often obscure, no matter how verbose the researchers are in the process of obtaining consent – in part because it’s often hard to predict who will benefit if new treatments are deemed to be effective, in part because it’s often hard to know how effective a treatment is likely to be, and in part because a big chunk of the benefit accrues to the researchers (articles published, grants funded, awards won) and the research industry (grant funding justified, administrative costs rationalized).

Nobody would accept a system in which people are forced to become medical research subjects.  In fact, the discoveries at Nuremberg about forced participation in medical experiments during the Second World War gave the impetus to the modern field of medical ethics.

But how much does it change the moral outlook if you are rewarded for allowing your body to be used by medical researchers with a cash payment?  The researcher has to be able to claim that her  subjects are not forced to participate – and the medical ethicists who are attached to the autonomy concept will still worry that the subject’s decision to lend his body for research will be coerced, not free and autonomous, if the payment is too grand.

For some classes of people, including children and addicts, payment is deemed to be especially coercive.  The thinking being that if the researcher were to offer $100  to an addict, the addict would use it to buy dope, and that would be harmful, and therefore the researcher would be doing a bad thing even though her research was really meant to do good.   Physician researchers always need to feel that they’re doing a favor to society (not to themselves).

Meanwhile, others decry payments that are too small, arguing that time, angst, and (sometimes) physical or mental suffering involved in being a research subject ought to be reimbursed at respectable rates.   Although the idea of a professional workforce of permanent research subjects, who might receive a retainer in return for surrendering their bodies and tissues for research, rubs physician researchers the wrong way.

Our society really likes medical research. We don’t want our doctors to stop looking for ways to help us to live longer and more comfortably.   Bodies must be used, but they shouldn’t be used without consent, they shouldn’t be purchased outright (that would be slavery), they can’t be paid too much, they shouldn’t be paid nothing, they shouldn’t be recruited for research use in perpetuity or receive the sort of ancillary benefits of employment that professionals get, and they should preferably not be “vulnerable” (young, developmentally disabled, imprisoned, or pregnant).

Which brings us back to kidney donation.  Should kidneys only be allocated anonymously and through a universal system that provides kidneys in accord with a complex algorithm that takes account of the likely benefit of the transplant?  Should there be a federally controlled market in kidneys, or at least some system that encourages donors through market-value incentives (like tax breaks), as Sally Satel has advocated?  Should there be a fully open market through which you could purchase the organ you need from a suitable and willing donor?

The conjunction of bodies-in-service-to-other-bodies and dollars makes the kidney question — like sex work, child labor, and medical research — fraught with moral meanings.  Simple solutions won’t serve.