Pre-existing Duty Rule (Common Law): The pre-existing duty rule stipulates that if one promises to perform an act that they are already legally obligated to do, this promise cannot serve as valid consideration for a contract. Consideration refers to some right, interest, profit, or benefit received by one party, or some forbearance, detriment, or responsibility assumed by another.
Q.: Why might the Talmud disagree with this rule?
A1: One primary reason for the Talmudic debate might be the desire for an added incentive to ensure action. While he may have already been obligated to assist her, the added promise could have served as additional assurance.
A2: Alternatively, the Talmud might see this promise as consideration, but due to certain rules, it cannot be enforced. Even though a benefit was conferred, as the Talmud suggests, public policy might prevent one party from demanding its fulfillment.
A3: Some argue that since he already had a moral obligation to assist her, her assertion that his action would serve as consideration for marriage is 'mere illusory'.
Note that the dilemma is still relevant:
Lord Mansfield [valid contract]: "[W]here a man is under a moral obligation which no Court of Law or Equity can enforce, and promises, the honesty and rectitude of the thing is a consideration." Hawkes v. Saunders, 98 Eng. Rep. 1091 (1782).
But see: "The difficulty we see with the doctrine is that if a mere moral, as distinguished from a legal, obligation were recognized as valid consideration for a contract, that would practically erode to the vanishing point the necessity for finding a consideration. This is so because in nearly all circumstances where a promise is made there is some moral aspect of the situation which provides the motivation for making the promise even if it is to make an outright gift." Manwill v. Oyler, 11 Utah 2d 433, 361 P.2d 177 (1961).
State Law: "A previous moral obligation is insufficient as a consideration to support an action to enforce an executory contract. (Parsons v. Teller,188 N.Y. 318.) A distinction is drawn between moral obligations and equitable obligations. An equitable obligation rests on some actual duty, unenforceable legally, such an infant's obligations [,] or debts barred by the Statute of Limitations [,] or bankruptcy, but a mere moral or conscientious obligation, unconnected with a prior legal or equitable claim, implies no duty and is not a sufficient consideration to support a promise. (Goulding v. Davidson, 26 N.Y. 604; McGuire v. Hughes, 207 N.Y. 516.) Pershall v. Elliott, 249 N.Y. 183, 188 (N.Y. 1928).
[Third-party benefit and pre-existing obligations] If a man said to a woman: Be betrothed to me with a loaf of bread, and she said: Give it to a poor person, she is not betrothed, even if it was a poor person who is dependent upon her, i.e., a poor person who regularly receives food from that woman. What is the reason for this? She could say to him: Just as I am required to give charity to him, so too you are required to give charity to him. Therefore, this donation is not an indication that she has agreed to the betrothal.
Editor Commentary:
Although Esav claimed he was dying, so that Jacob was obligated to give him food, the sale was nevertheless complete. This would have has practical implications for the inheritance laws. Yet, the Torah says the sale was complete.