A thing which you have enjoyed and used as your own for a long time, whether property or an opinion, takes root in your being and cannot be torn away without your resenting the act and trying to defend yourself, however you came by it. The law can ask no better justification than the deepest instincts of man.  (The Path of the Law, Oliver Wendell Holmes, Jr., #10 Harvard Law Review 457, 1897)


Justice Holmes may not have realized it, but he was expressing a concept found in the Gemara Yerushalmi: an instinct called the endowment effect.


The endowment effect postulates that the negative emotional impact of losing something is more intense than the positive emotional impact of gaining something.  Studies have found this to be true for adults and even more intensely for children.


[To determine the payment for pain,] one estimates how much a person would ask to be paid in order to be willing to suffer such pain.   Rabbi Ze’ira said, “one sees a person and asks him, how much would you give that such pain would not be inflicted on you? And what he says, you give to him.”  Mar Ukva said, “the Mishnah said ‘how much would a person ask to be paid in order to be willing to suffer such pain.’  How can you say what you said? [I am amazed that you think it means how much the victim would give!  According to you, the Mishna should have said “give,”  but the Mishna says how much would the victim ask to receive! (based on Pnei Moshe, d.h. V’saimar ochain)]  Rather,  “one sees a person and asks him, how much would you ask to be paid to agree to suffer such pain, and what he says, you give to him.”  (Yerushalmi, Babba Kamma 25a,b; perek 8, halacha 1)


What’s the difference?  Did Mar Ukva challenge Rabbi Ze’ira simply on the basis of textual accuracy or is there a nafka minah, an halachic ramification that Mar Ukva was addressing?


What are the two versions of the Mishna?

Mar Ukva: How much would a person who is going to suffer a loss, in this case, the loss of his comfort due to pain, wish to be paid for his loss, a loss which is inevitable.

Rabbi Ze’ira: How much would a person pay to avoid that loss if it were avoidable.


Based on the endowment effect, a person would pay more in order not to lose something than he would ask to be paid for suffering a loss.

It could be that Mar Ukva is challenging Rabbi Ze’ira on the basis of the endowment effect.  Mar Ukva holds that Mishnah refers to the amount one would ask to be paid for a loss.  Rabbi Ze’ira’s holds that the Mishna refers to the amount one would pay in order to avoid a loss, which, given the endowment effect, would be a lesser amount.


Researchers in behavioral decision theory have developed a growing line of evidence that people appear to value a commodity that they own much more than an identical commodity that they do not own. Researchers and legal scholars alike have labeled this phenomenon the endowment effect.

The endowment effect occurs with possessions as banal as coffee mugs, chocolate bars, and pens. Subjects given these items are generally unwilling to sell or trade them.

It seems likely that there is an endowment effect for body parts.

The data indicate that the endowment effect is really only a resistance to parting with a commodity, and ownership does not reflect a change in the value of a commodity to its owner. The endowment effect is merely a part of how people construct preferences, and it indicates only that when choosing whether to part with a commodity, people are somewhat more resistant than a conventional rational model would predict.

Cognitive psychologists have attributed the effect to the broader phenomenon of loss aversion-the tendency for people to attach more importance to losses than to gains. In numerous contexts, psychologists have demonstrated that people sacrifice more to avoid losses than to obtain gains of a similar magnitude.  Consequently, people tend to prefer the status quo, which would produce an endowment effect.

(Excerpted from: Jeffrey J. Rachlinski and Forest Jourden, Remedies and the Psychology of Ownership, 51 Vanderbilt Law Review 1541, 1998)


When you formulate your kavana in taking something from a child or offering to give her something on condition, keep the endowment effect in mind.


I told my daughter Gila I would buy her a new watch if she set the table for Shabbos four weeks in a row without being reminded.  She didn’t.  How upset do you think she will be when she loses the watch she’s been looking forward to getting?


I told my son Gershon that I would take away his watch if he didn’t put the garbage out front every Tuesday evening for four weeks in a row.  He didn't.  How upset do you think he will be when I take away his watch?


Even if the watch Gila has been looking forward to getting and the watch that Gershon is about to lose have the same price, Gershon’s perceived loss will be greater, perhaps significantly so.


Be sure to bear this in mind twice.  Once, before you take something away.  And again, when you determine what it will take for your child to earn it back.


Rabbi Ackerman is the author of Confident Parents, Competent Children, in Four Seconds at a Time

Available at bookstores and on Amazon.

He can be reached at 718-344-6575