Dear Economist
Dear Economist,
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I cohabit: dual career, equal partnership. My partner has a child from a previous marriage who lives with us. We co-own our home, and we contribute equally to a joint account for paying the bills. We have had to hire a housekeeper, since he does not want to clean the house and I do not want to do all the housework. Should I be paying for the food and utilities consumed by his child? Should I have to pay the same amount towards the housekeeper that he does?
Troubled in Paradise, via e-mail
Dear Troubled,
You need to work out whether the net benefit of the housekeeper is positive. You will tend to exaggerate the value of a clean house while your partner pretends not to notice grime. So you need a clever technical procedure called a Clark-Groves mechanism, which will give you and your partner an incentive to tell the truth about how much you value the housekeeper.
Both of you should pay a few thousand pounds into a "trust fund for honesty". Then write down the net benefit to you of having a housekeeper and paying half the cost; your partner writes down the net cost to him of the same arrangement. If the benefit exceeds the cost, hire the housekeeper and share the cost equally, but you must also pay the figure he wrote down to the trust fund. He receives the figure you wrote down from the trust fund. (They will not be the same, which is why you need the fund.)
Neither of you will benefit from lying because what you pay or receive is not a function of what you write down.
This is a tremendous fuss, of course. But it will be interesting to see what happens when you use the procedure to see how much he values the kid.
将同居AA制进行到底
亲
爱的经济学家：
我目前与人同居：我们两人都工作，实行AA制。我的男伴有个前妻生的孩子，现在和我们一起生活。我们共同拥有住房，有一个用于支付各种费用的共同账户，并均摊这些费用。我们得雇一个保洁员，因为他不愿意打扫房间，而我则不愿意承担全部的家务。我是否应该支付他孩子的食品及公用设施费用呢？是否应与他均摊付给保洁员的费用？
天堂中的困惑女人，通过电子邮件
亲爱的困惑女人，
你需要算计一下，雇保洁员的净收益是否为正值。你会倾向于夸大房间清洁的价值，而你的男伴则可能装作不介意污垢。因此，你需要一种聪明的技术程序，这种程序名为“克拉克－格罗夫斯机制(Clark-Groves mechanism)”，该机制能促动你和你的男伴讲真话，看看你们究竟认为保洁员的价值是多少。
你们两人应该各拿出几千英镑，放入一个“诚实信托基金”。然后，你写下雇保洁员为你带来的净收益，并支付一半的成本；你的男伴则写下他为同一安排所需付出的净成本。如果收益超过了成本，就该雇保洁员，并均摊成本，但你同时还必须向信托基金支付他所写下的数目。他从信托基金得到你写下的数目。(这两个数目将有所不同，这也正是你们之所以需要这项基金的原因。)
你们两个人都无法从撒谎中得到益处，因为你们写下的数目，无法左右自己付出或得到的钱数。
当然，这种做法极为麻烦。不过，如果你用这种程序，来看看他对孩子有多看重，事态的发展一定会很有趣。
