Colbert on school choice in Wake County

Stephen Colbert explains the logic behind returning to a system of local schools (video, funny).

HT: Tim Gray

Jobs in kidney exchange

Methodist Specialty and Transplant Hospital in San Antonio is advertising for a Vice President, Transplant Services

In their ad they highlight their active kidney exchange program:
"Methodist Specialty and Transplant Hospital Recognition
"•# 1 SWAP Program in the country

"•# 1 kidney exchange program and 3-way paired kidney exchange program. Most recently performed the world’s largest kidney exchange transplant chain at a single center on November 11-13, 2010 with 16 recipients and 17 Donors involved and the transplant.

"•Performed 25 heart transplants year to date with a 95% success rate and completed 13 ventricular assist devices.

"•For additional information about the transplant program visit: www.texastransplant.com “METHODIST SPECIALTY AND TRANSPLANT HOSPITAL”

Homophobia: gay sex remains a repugnant transaction for many

If a repugnant transaction is one that some people want to engage in and others don't want them to, then sex is surely the most ancient. Some of this comes from the desire to control procreation (and be able to identify the father of each child), but that doesn't account for the repugnance of homosexual sex.

Elsewhere I've posted how this ancient repugnance seems to be crumbling, as same sex marriage slowly becomes legal in more places (and as the U.S. armed services have been slowly pushed to more clearly welcome the service of gay soldiers). But two recent articles make the point that homosexual sex is still a widely repugnant transaction.

Gays in Africa face growing persecution, human rights activists say
"In Uganda, a bill introduced in parliament last year would impose the death penalty for repeated same-sex relations and life imprisonment for other homosexual acts. Local newspapers are outing gays, potentially inciting the public to attack them, activists say."

"In Uganda, we look at homosexuality as an abomination. It is not normal," said Nsaba Butoro, Uganda's minister on ethics and integrity and a vocal supporter of the bill. "You are talking about a clash of cultures. The question is: Which culture is superior, the African one or the Western one?"

"More than two-thirds of African countries have laws criminalizing homosexuality. In May, a judge in Malawi imposed a maximum prison sentence of 14 years with hard labor on a gay couple convicted of "unnatural acts" for holding an engagement ceremony. Malawi's president pardoned the couple after international condemnation, particularly from Britain, Malawi's largest donor.

"Gays have also been attacked this year in Zimbabwe, and in Senegal their graves have been desecrated. Gays in Cameroon have been attacked by police and targeted in the media. In Gambia, President Yahya Jammeh has vowed to expel gays from the country and urged citizens not to rent homes to them.

"One exception is South Africa, whose constitution was the first in the world to outlaw discrimination based on sexual orientation and is among a few countries in the world that have legalized same-sex marriages."

And here's an article closer to home: Gay Bashing at the Smithsonian, about an artwork removed from the exhibit by the National Portrait Gallery recently.

European carbon markets suspended

The suspension of trading on European carbon emissions markets has been covered fairly widely, with the most interesting (and critical) story I've seen being this one from the Telegraph. European carbon market suspended over fraud fears: "The European carbon market has been thrown into turmoil after the scandal-hit scheme was suspended for a week over suspicions of fraud."


"More than €2bn (£1.7bn) of trade is likely to be disrupted after the European Commission said it would prevent transactions until January 26.
"The suspension follows allegations that 475,000 carbon credits worth €7m were stolen in a hacking attack on the Czech carbon register. It appears that the intangible allowances were bounced between eastern European countries before disappearing without a trace."
...

"This is not the first challenge to the credibility of the €90bn annual market in carbon allowances
"Under the flagship scheme, companies need permits to emit carbon dioxide as part of the global fight against climate change and polluters are granted a certain number of emissions allowances that can be traded.
"But it has been plagued by fraud, with Europol estimating that carbon trading criminals trying to play the system may have accounted for up to 90pc of all market activity in some European countries during 2009. Fraudulent traders mainly from Britain, France, Spain, Denmark and Holland pocketed an estimated €5bn. Carbon allowances are particularly susceptible to fraud because they are high value, intangible and easily moved between different countries."

Kidney chains in India, and a millionaire nondirected donor

Kidney chains are coming to India, and one of the first (maybe the first) non-directed donors is a millionaire businessman: Kidney donation chain bank set up in Trichur

"19 January 2011 TRIVANDRUM — A leading industrialist in Kerala has set into motion a novel kidney donation chain by deciding to donate one of his kidneys to a stranger.

"Kochouseph Chittilapally, owner of V-Guard group of companies, signed the papers to donate his kidney to 48-year-old Joy from Palai on the occasion of the launch of a kidney bank at Trichur on Monday.

"The bank was set up by the Kidney Federation of India (KFI), founded by Fr Davis Chiramel, who had shown the way by donating one of his kidneys to a stranger one-and-half-years ago. The kidney chain — the first of its kind in India — is possible because of a new type of organ donation called a paired donation, in which a person who needs a kidney can get one by bringing up a donor.

"Joy became eligible to get the kidney after his wife, Jolly, agreed to donate her kidney to one Shamsuddin. His wife, Sainaba, will give her kidney to one John, and whose mother in turn will donate her kidney to Baiju.

"The chain ended here as Baiju could not get a donor among his close relatives. Fr Chiramel is not disappointed. He said he will be able to launch another chain shortly as there were people willing to donate their kidneys. “I was flooded with calls after the kidney bank was launched. Out of 150 callers I had till Tuesday afternoon, 10 were willing to donate their kidneys. We will get them medically examined and put them in the chain if they are fit to donate their kidneys,” the priest said."

Here's another story: Crorepati’s kidney in donor chain

HT: Nikhil Agarwal

Barter in a recession

In a Tight Holiday Season, Some Turn to Barter

"The proliferation of Web sites with names like Swap.com and SwapMamas have moved swaps from the home and the community center to online bazaars with millions of users. No industry figures exist on the number of for-profit startups, but officials at one of the largest, Swap.com, said they have over a million registered users and an inventory of 15 million items at any given time.

"ThredUP opened business in April as a clothing exchange site and expanded this month to toys. Mrs. Spitzer signed up as a member in August.
She said that she used to buy new clothes for her three children, all under age 7, every couple of months and then give them away as her children outgrew them. But after she joined ThredUP, she began viewing her children’s hand-me-downs as currency."

Swap.com and ThredUP charge a small fee for each trade ($1 and $5). I didn't see such a fee on SwapMamas, which also encourages people to offer their used goods as gifts when they don't find a coincidence of wants, and has a reputation system that is intended to make frequent givers also favored recipients of gifts.

Greg Lewis' market design course at Harvard

My colleague Greg Lewis will be teaching a market design course this semester, and sends this email:

"I just wanted to advertise the market design course I'm teaching this semester (Econ 2056b).  The syllabus can be found here.  It's designed to be a complement to both Al and Peter's class (Econ 2056) and Ariel's IO class (Econ 2610), and it's a mix of theory and structural empirical techniques.

I've mixed up the style of the course a bit from past years: from pretty much the second week on, we'll be alternating between lecture and discussion --- which means the students will have to work a little harder and participate more, and hopefully get more out in the end.

Hope to see you there!

Cheers
Greg"

Organ donation in Tucson tragedy

9-year-old shooting victim's organs help save child

"Christina-Taylor Green, the 9-year-old girl killed in Saturday's shootings in Tucson, donated her organs.

"She was one of six people killed in the shooting that targeted U.S. Rep. Gabrielle Giffords outside a Safeway store northwest of Tucson. Giffords remains in critical condition.
...
"And a friend helping the Green family said they received a call yesterday from the organ donation network, telling them that Christina-Taylor's donation had already saved the life of a child on the East Coast."

HT: Bernie Keller

Economics job market in Europe

The big marketplace for new Ph.D. economists is the one that takes place in North America each year in early January (see this recent paper), but in recent years the Royal Economic Society has attempted to get one going in Europe.

The 6th PhD Presentation Meeting of the Royal Economic Society  is going on this weekend, on Saturday 15th and Sunday 16th January 2011 at City University London.

"The aim of the event is to provide a service both for UK and European university economics departments wishing to recruit lecturers, and for PhD students seeking academic jobs in the UK or elsewhere in Europe. This annual meeting has grown to be an extremely successful event, well supported by both students and potential employers. The event consists of two days of students’ presentations and poster sessions. Participating institutions (pdf) attend these presentations and are also allocated a room at the conference site in order to arrange individual appointments with participating PhD candidates (pdf) during the course of the conference. "


Good luck to all those on the market.

(For departments interested in the theory of matching, I notice that one of the new Ph.D.s in attendance is Alex Nichifor, who is a coauthor of a very good paper: Stability and Competitive Equilibrium in Trading Networks . (His coauthors are John Hatfield, Scott Kominers, Mike Ostrovsky, and Alex Westkamp, and his Ph.D. advisor is Bettina Klaus.))

Tribal customs of academic disciplines

Some of the different ways that different academic disciplines organize their scholarship, and the signals they send about it, are discussed in a recent column in the Chronicle of Higher Education about tenure reviews.

"A fair analysis of a tenure candidate requires that the committee members know (or learn) about the culture of the relevant academic discipline, particularly with respect to norms of publication numbers, venues, authorship order, conference presentations, invited talks, and student or postdoctoral advising.

"Considerable variation in those features exists across academe, even within science and engineering fields. Whereas one academic discipline might value short publications in highly selective conference proceedings over peer-reviewed journal articles, another requires peer-reviewed journal articles (in high-impact journals) as the primary indicator of productivity. Similarly, one discipline might alphabetize author order, another always has the "brains behind the project" as the last author, and another considers the first author listed to be the most important. Some fields expect assistant professors to have advised one or more Ph.D. students through to the completion of their degree, but in other fields that would be considered unusual."

The different customs of publication order present some opportunities in interdisciplinary collaborations of the kind that arise in market design, particularly since the authors publishing outside of their disciplinary journals are freed from the burden of sending signals.

In France, civil unions aren't just for same sex couples

A pacte civil de solidarité in France is a civil union, something like a civil marriage, originally intended to help same-sex couples formalize their relationship, without expanding the official scope of marriage.  But these civil unions are easier to dissolve than formal marriages, and (the NY Times reports), opposite sex couples are also finding this less formal kind of union attractive: In France, Civil Unions Gain Favor Over Marriage

"French couples are increasingly shunning traditional marriages and opting instead for civil unions, to the point that there are now two civil unions for every three marriages.

"When France created its system of civil unions in 1999, it was heralded as a revolution in gay rights, a relationship almost like marriage, but not quite. No one, though, anticipated how many couples would make use of the new law. Nor was it predicted that by 2009, the overwhelming majority of civil unions would be between straight couples.

"It remains unclear whether the idea of a civil union, called a pacte civil de solidarité, or PACS, has responded to a shift in social attitudes or caused one. But it has proved remarkably well suited to France and its particularities about marriage, divorce, religion and taxes — and it can be dissolved with just a registered letter."

Meanwhile, in Britain, which also has civil partnerships, a lawsuit is underway to change the fact that both same sex marriage and different sex civil partnerships are illegal:

"Eight British couples will argue that the twin bans on same-sex marriages and heterosexual civil partnerships are unlawful and should be reversed.

"Over the last two months four homosexual couples have all been refused marriage licenses at register offices across England, while four heterosexual couples were turned away when they applied for civil partnership status.

"The couples will file a joint application to the court today, which is the fifth anniversary of the first civil partnership ceremonies in England."  

Pictures from a matching conference (and a new matching paper)

I returned from Milan to the following cheerful message from Atila Abdulkadiroglu:

Dear all,

I hope you have had a cheerful holiday season, happy new year to you all.

I thought it would be better late than never, so here are also some photos from the "Roth and Sotomayor: Twenty Years After" conference: http://duke.edu/~aa88/RothandSotomayorTwentyYearsAfter/

This is all of the photos I got from our media relations person, I hope she got all of us at least in the first photo.

I would also like bring your attention a recent paper of mine:

"Generalized Matching for School Choice" ( http://duke.edu/~aa88/articles/GeneralizedMatching.pdf )
This paper makes the case that neither a one-sided matching model nor a two-sided matching model is adequate enough to capture some salient features of the school choice problem. It introduces a natural generalization to the matching models, and a natural extension of the stability notion. It characterizes student optimal stable matchings and introduces a new matching algorithm, Stable Transfer Cycles, that reduces to TTC when the problem is one-sided and becomes equivalent to Gale-Shapley's student optimal stable matching mechanism when the problem is two-sided.

Comments would be most welcome."

And here's the conference website to which the pictures refer:Roth and Sotomayor: Twenty Years After, May 7-9, 2010, and the first picture...

Specialized dating sites for the disabled

Searching for a mate is hard work, and it can be hard to find a match if you have special needs. So there's a demand for specialized dating sites: Difference Is the Norm on These Dating Sites

"Several dating Web sites for singles with health problems have started up in the last few years. Ms. Nevius joined Dating 4 Disabled, a site for people with an array of disabilities, including paralysis and multiple sclerosis. Other sites include NoLongerLonely, for adults with mental illness, and POZ Personals, for people who are H.I.V-positive."
...
"He said the worst part of dating was the anxiety over disclosing his H.I.V. status. Getting to know someone in an online community of people with H.I.V. allows relationships to form without the burden of the big reveal hovering overhead.


“Here everyone knows you have H.I.V.,” he said, “so it gets that barrier out of the way.”

"Another site, Prescription4Love, has communities dedicated to sexually transmitted diseases and physical disabilities, but also to other diseases that don’t conjure images of romance and intimacy, like diabetes and Parkinson’s. The site was created by Ricky Durham, whose late brother suffered from Crohn’s disease — a condition that came with literal baggage.

“He was a good-looking boy,” Mr. Durham said. “But when do you tell a girl that you have a colostomy bag? The first date? The third? There’s no good time.”

"Awkward issues that come with an illness can be discussed frankly and openly in an online space in which everyone is dealing with something out of the ordinary.

“Sexuality, travel, mobility, pain: Everything takes on a different dimension,” said Merryl Kaplan, who is in charge of member services for Dating 4 Disabled.

"The anonymity of the Internet allows people to be forthcoming and honest about what they are truly looking for in a companion. Among the almost 12,000 members of Dating 4 Disabled, for example, many specify the types of disabilities they would be open to dealing with in a long-term relationship.

“Like anyone else, people with disabilities have different preferences,” Ms. Kaplan said. “Someone with good mobility may prefer someone also mobile; others don’t limit at all.”

Tips, Tip Pooling, and Tip Credits

Restaurant wait-staff in the United States make a significant part of their incomes in tips left by satisfied or habit-driven or social-norm-conscious patrons (but this isn't a post about the large behavioral literature on restaurant tipping, e.g. here). A consequence of this is that restaurants and certain other employers can receive "tip credits" that release them from the obligation to pay the minimum wage, since their employees will be having part of their wage paid by their customers.

There's a body of law about what employers can and cannot do with tips (e.g. require them to be pooled, shared with non wait-staff, etc.), and about what constitutes a tip (e.g. not all "service charges" go to the server): see e.g. NoLo.com's  Tips, Tip Pooling, and Tip Credits: What Service Employees Need to Know

There are presently a number of lawsuits going through the courts about this, and some new legislation, discussed in an op-ed in the NY Times by Tim and Nina Zagat of Zagat's fame: Adding Fairness to the Tip

With the new year have come some new regulations in NY: New Rules Impose Systems for Sharing of Tips
"The new regulations apply to workers in restaurants and hotels and cover a number of issues, including who should pay for laundering “wash-and-wear” uniforms, like special T-shirts. The rules also raise the minimum wage for tipped employees, to $5 from $4.65 an hour for food service workers and to $5.65 from $4.90 an hour for service workers, a category that includes coat check workers in a restaurant or porters in hotels. (There is a separate minimum for workers at resort hotels.)


"The new rules also define the job categories that are eligible for shares in tips from the dining room: food service workers only, including waiters, bartenders and bussers, as well as sommeliers and hosts, provided they are not managers.

"The new rules allow restaurants to dictate both the system and the percentage allocated to each job category. Gratuities can be combined in a pool, to be divided by all the staff members who have helped a team effort. Or, individual servers can collect their own tips and give portions, or shares, to members of the team.

"The Labor Department will require that employers keep records of tip pools and shares; the records could be examined during investigations undertaken by the department on its own or in response to complaints.
...
"Higher-end, full-service restaurants tend to favor the pooling of tips, because it breeds less squabbling over stations and shift assignments, provides an incentive for teamwork and encourages the servers to police their own performance.


"The new regulations generally limit the pool to service workers in the dining room who interact with customers directly — like waiters — or indirectly, like servers who ferry plates from the kitchen to a station where another server picks them up and delivers them to the table. But bartenders, who prepare beverages for the dining room in a role analogous to that of a cook, can also share in the tip pool, even though kitchen staff members cannot.

“A lot of this arises from custom and tradition,” Ms. Lindholm said. “If you’re looking for perfect logic in this, it isn’t there.”

Wikipedia fundraising, randomized experiments

You know those fundraising appeals that appear at the top of Wikipedia pages? They are randomized so that reliable information can be collected about which ones attract donations.

The Wikimedia team writes:

"Since August, the Fundraising Committee has been running banner & landing page tests. These have evolved from weekly Thursday afternoon tests, which helped us get all of our systems in order and determined which messages would best motivate our donors before the launch of the fundraiser - to almost daily tests introducing new banners and landing pages as we continue to tweak our current campaign.

"Check out the Fundraising Updates page where we discuss what we've learned so far and upcoming tests and challenges."

Game theory for college teachers at the AEA continuing education program

Preliminary reading list for an introduction to Game Theory at the AEA Continuing Education Program January 2011 taught by Avinash Dixit and David Reiley.

Meant for college teaching at all levels, starting with freshmen and going up to writers of senior theses,
it includes  sections taught by Reiley that include mateial that will be familiar to readers of this blog, on VI. MARKET DESIGN AND ALGORITHMS
IV. AUCTIONS AND FIELD EXPERIMENTS


It also includes the first draft of a new book by Michael Suk-Young Chwe,
Folk Game Theory: Strategic Analysis in Austen, Hammerstein, and African American Folktales

Slavery in the U.S.

At the conference I'm attending in Finland, there's been a good deal of discussion (with more to come) of repugnant transactions, with an undercurrent of concern that globalization and other kinds of encroachment of markets on traditionally non-market ways of allocating resources will inevitably cause things presently regarded with repugnance to become more customary.

It's good to remember that our repugnance at certain transactions doesn't have to diminish over time (as does happen with many formerly repugnant transactions like same sex marriage).  Slavery (and indentured servitude, and other forms of servitude) were once regarded with much less repugnance--certainly much less nearly universal repugnance--than they are today.

The NY Times recently published a Civil War era map of where slaves were in the United States in 1860:
Visualizing Slavery

"South Carolina, which led the rebellion, was one of two states which enslaved a majority of its population, a fact starkly represented on the map."
                                              
                                               http://www.nytimes.com/interactive/2010/12/10/opinion/20101210_Disunion_SlaveryMap.html

Markets, broadly defined

I'm in Helsinki, participating in the second workshop of the Markets & Marketization program, that will bring together philosophers and philosophers of science with economists, sociologists, political scientists and others interested in markets very broadly defined.

Workshop II  Friday-Saturday, 7-8 January, 2011; Tentative program

Friday 7.1.

10.00 - 11.00 Alvin Roth (Harvard): "What does market design teach us about markets?"

11.10 - 11.30 Comment: Patrik Aspers

11.30 - 11.50 Comment: Emrah Aydinonat

11.50 - 12.30 Discussion

14.00 - 15.00 Ronald Noë: On biological markets (title TBA)

15.00 - 16.00 Risto Heiskala: "Coordination of human interaction: the BTCIEMP scheme"
(’BTCIEMP’ stands for: biology, traditions, cultural categorization, ideology, economy, military power and political power)

16.30 - 17.30 Jens Beckert: On the sociology of markets (title TBA)

Saturday 8.1.

10.00 - 11.00 Debra Satz (Stanford): The Moral Limits of Markets

11.10 - 11.30 Comment: Adrian Walsh

11.30 - 11.50 Comment: John O’Neill

11.50 - 12.30 Discussion

Blasphemy law in Pakistan

One of the oldest repugnant transactions, different worship, is as repugnant as ever in Pakistan: Pakistanis Rally in Support of Blasphemy Law

"ISLAMABAD, Pakistan — A crippling strike by Islamist parties brought Pakistan to a standstill on Friday as thousands of people took to the streets, and forced businesses to close, to head off any change in the country’s blasphemy law, which rights groups say has been used to persecute minorities, especially Christians.
...
"In fiery speeches across all major cities and towns, religious leaders warned the government on Friday against altering the law, which carries a mandatory death sentence for anyone convicted of insulting Islam.
...
"The human rights commission has documented scores of cases in which men have been harassed for being Christian or for being members of the Ahmadi sect, a minority group within Islam, and then accused of blasphemy. The mere fact of being a Christian or an Ahmadi in Pakistan makes a person vulnerable to prosecution, the commission says. Often the mere accusation of blasphemy has led to murders, lynchings and false arrests."


It turns out that the accusation of being against the blasphemy law isn't good for you either: Salman Taseer assassination points to Pakistani extremists' mounting power

"Taseer's apparent killer cited his boss's stance against a controversial anti-blasphemy law in justifying his actions. As the embattled, pro-U.S. PPP sought in recent days to win back defecting allies that also include a small Islamic party, it had already said it would not support a proposal to change the blasphemy statutes. That left Taseer one of the few vocal champions of the move, which hard-line religious organizations had labeled a Western conspiracy.

The laws have drawn scrutiny since a Christian woman was sentenced to death in November for allegedly criticizing the Muslim prophet Muhammad. Taseer had called for her pardon, leading religious groups to denounce him as an "apostate" and burn effigies of him during a nationwide strike last week in support of the law. One Muslim cleric has offered $6,000 to anyone who kills the woman, who remains in jail."

More on the debate over kidney sales: transcript of interview

In my earlier post, Dubner interviews me about kidney sales, I promised to link to a transcript when it became available, and now it has: there's a link at the bottom of the Freakonomics post You Say Repugnant, I Say … Let’s Do It!

Dubner interviewed me for about an hour and a half, so he and his producer Chris Neary had to do lots of editing to produce the half hour or so podcast. I recall a pair of questions, one of which made it into the show and one of which was left on the cutting room floor (or wherever unused electronic files are left).  The question that made it in was about what makes many people view kidney sales as repugnant. The question that didn't make it was, if I were asked to help design a market in which kidneys could be sold, what would be my primary concerns.

Regarding what is behind the repugnance of kidney sales, here's the text of my reply included in the transcript:
"Al Roth: The late Pope John Paul wrote about this and he objects strongly to the sale of kidneys but thinks the donation of kidneys is a very good thing, though if we do it for money is a very bad thing...I think his feeling is that it turns people from ends into means which is a bad thing in itself. So that’s one nature of objection. 
Another kind of objection is that it might be OK if I offered to buy your kidney because you’d be a hard guy to exploit, you’re a successful, financially solvent person, but pretty soon we’d start seeing the desperately poor and maybe they would in some sense be acting against their self interest, they would be being exploited or coerced even, by the temptation of the money in ways that if they could use their better judgement they wouldn’t want to be.  So that’s sort of a coercion argument. 
And then there’s a slippery slope argument that says if we started allowing people to sell their kidneys, it would be primarily poor people who would sell their kidneys, and pretty soon we would start hearing political discussion that said, ‘you know, we don’t really need unemployment benefits, we don’t really need aid to families with dependent children because after all, everyone’s got two kidneys and they can take care of themselves by selling a kidney if they need to’...and that makes us a much less desirable society to live in."


I don't have a transcript to consult about what I said when they asked what I would do if asked to help design a kidney market, but as I recall, my answer went something like this.
The first thing I'd want to think about is what kind of review we would want to use to judge if the market had been a success ten years (or longer) after it had been started. The criteria we'd surely want the market to be evaluated on would include:
 How had the donor/vendors fared?: were they healthy and well treated, and respected, and did they encourage new potential donor/vendors to make the same choices they had?
How had patients with kidney disease fared?: were they receiving healthy kidneys, had the waiting list for transplants largely disappeared, were kidneys being allocated in ways that were widely seen as equitable?


To focus thoughts for future debate, we might want to think about a system in which only the federal government could legally pay for a live kidney, and would have a mandate to set the price (and associated benefits like follow-up medical care) high enough so that there would be a waiting list of donor/vendors, who could e.g. be expected to undergo regular health and suitability tests (suitability being a broad term meant to include physical and mental health, deeply informed consent, etc.)  for a year before being accepted as donor/vendors, and that the kidneys obtained in this way would be allocated anonymously through some regulated procedure that might resemble the current procedures for allocating deceased-donor organs.

In terms of how I've interpreted the ongoing debate between those in favor of sales and those against, I  think that a good deal of the coercion concern can be addressed by an appropriately designed one year waiting period, although I say that without having recently talked to someone who makes that argument with conviction.
I don't see any easy way to bridge the gap between those who think that selling kidneys is a bad thing in and of itself, not to be traded off with possible benefits of other sorts (e.g. to patients and perhaps to donor/vendors), and those who don't see it that way, or who feel that the current dire circumstances of many thousands of those with kidney disease gives legitimate counterweight to this concern.
And the slippery slope concern is the one that personally gives me the most pause. I can see how appropriate legislation would prevent e.g. your bank from asking for a kidney as collateral, but I can't see any way to be sure that making kidneys a potential financial asset wouldn't make us a less sympathetic society (even though a one year waiting period and other qualification tests would limit how much kidney sales could be used as a justification for cutting unemployment insurance in particular).

My work on kidney exchange has largely avoided being enmeshed in this debate, since the "in kind" kidney exchange doesn't seem to arouse repugnance. Thus for example Debra Satz' recent book Why Some Things Should Not Be For Sale: The Moral Limits of Markets, Oxford University Press, 2010, finds little to object to about kidney exchange, but largely disapproves of kidney sales. (I expect to meet Professor Satz for the first time this weekend, at a philosophy of economics conference in Helsinki...)