Our Gemara on Amud aleph discusses financial protections that the rabbis instituted for young adults, even though past bar mitzvah age:

Rather, the Sages maintain that a child’s inclination is to be attracted to money. And if you say that his sale is a valid sale, there may be times that there are potential buyers who rattle the dinars before him in order to tempt him to sell, and he will go and sell all of his father’s property. That is why the Sages ruled that all of his sales are not valid. But with regard to a gift, if he did not derive benefit from the recipient, he would not give him a gift. The Sagestherefore said: Let the gift of an orphan be a valid gift, so that people will perform beneficial matters for the orphans, as the orphan can reciprocate by giving gifts.

Rashbam and Rabbenu Gershom understand it as if they do favors and give gifts to others (gemilus chassadim, the Hebrew term for acts of kindness and charity), others will be more inclined to reciprocate. 

This is an interesting notion that the altruistic moral idea of being kind can also be pragmatically viewed as part of a quid quo pro and the social contract. It is notable that both commentaries use the term, gemilus chassadim, because using such a catch phrase implies equivalence and that it is not morally inferior.

This brings to mind a famous Rav Yisrael Salanter story (whose origin I cannot locate.) Once he remarked that he envied the inkeeper who able to perform chessed all day long, tending to his guests. A student questioned why this was so laudable, given that the inkeeper charged a fee for room and board. Rav Yisrael answered, “ Nonetheless it is chessed.”

We might say Rav Yisrael meant that there were plenty of opportunities to show kindness by attitude and intentions, as well as the subtle extras not dictated by the strict financial contract. But he might have even meant that it was chessed no matter what, even if just reciprocal, with no extras. The latter is supported by what we saw in our Gemara. Kesuvos (72a) expresses this idea more explicitly, when describing the “pay it forward” nature of attending to the needs of the dead. The dead cannot pay us back, but what we do for others will be done to us:

Rabbi Meir used to say: He who eulogizes others, people will eulogize him; he who buries someone, people will bury him; he who lifts others to bring them to burial, people will similarly lift him to bring him to burial; he who escorts others out for burial, people will similarly escort him; he who carries others, others will carry him. Therefore, one who does not come to a house of mourning to comfort the bereaved will himself not be treated with proper dignity when he dies.

The Ritva (ibid) is explicit in explaining that this is the social contract: “One is treated as he treats others.”

If this is so, we might wonder why the apparent acceptance of the pragmatic exchange of favors without any suggestion that the higher form of morality would be to perform kindness without expectation of reciprocation? You could technically answer that the Gemara was only emphasizing the practical aspects to motivate, but in truth it is better to perform kindness without any assumption or demand for a matching future return. However, it seems to be a glaring omission that somewhere in these discussions this is not mentioned.

I believe the answer is that even though the above is true and all mitzvos should be ideally performed altruistically, the sages also were stressing something beyond the practical aspect of the social contract. The social contract is not merely a calculated exchange but rather a critical concentration of a continuously growing sense of commonality and human bond. In other words, the sense of reciprocity itself becomes a vehicle of a resonance that builds a kinder society over generations. This might be compared to the joys of feasting at a seudas mitzvah (festive meal honoring a holiday or ritual.) The food and merriment are not incidental rewards for the altruistic pure achievement. Instead they are the expression and creation of an ongoing bond between Man and God by celebrating the experience.

I believe this is a subtle but significant and true distinction. Judaism is often practical and transactional in how it describes human morality and relationships, but it’s bigger than merely pragmatism about human nature. Rather, it uses human nature, symbols and experiences to enhance our bonds with our loved ones and God by giving and receiving pleasure and goodness.