One of the cherished presumptions of the rabbis is that the Patriarchs observed the Torah even before it was given. It would have been simple enough to argue that no one could be expected to observe laws that had yet to be given. But the rabbis operated with a different set of expectations. For the rabbis, the Torah represented eternal truths and timeless practices that define the apotheosis of human behavior. Hence, it was inconceivable to the rabbis that Abraham, Isaac, and Jacob would have behaved in any way contrary to the laws given to Moses half a millennium later. Thus, for example, the rabbis note that when Abraham served the angelic guests whom he welcomed into his tent, he served them both dairy and meat dishes (Genesis 18:8) but he served the dairy dishes first, conforming to the rabbinic interpretation of the Torah.
Similarly, Italian Rabbi Ovadiah Seforno (1475–1550) explains that Isaac did not violate the Torah that prohibits the father from denying his firstborn son his birthright (Deuteronomy 21:16) even though that is precisely what Isaac did to Esav. Rather, Isaac complied with the Torah – as understood by the sages of the Talmud (Bava Batra 133b) – that allows for transferring the birthright to another son when the firstborn wickedly misbehaves. Indeed, Seforno points out, that is how the Biblical Book of Chronicles (I Chronicles 5:1) explains how Jacob could transfer the birthright away from his firstborn son Reuven: “when he defiled his father’s bed, his birthright was given to the sons of Joseph…”
As much as a way of justifying a questionable rabbinic assumption, there is another lesson to be learned. Contemporary society is obsessed with “rights,” understood as some kind of entitlement. (The United Nations counts thirty, but others count many more.) By virtue of who I am I deserve certain advantages. But the rabbis were obsessed with duties, obligations to perform. And those who fail to perform these duties get nothing and should expect nothing. The birthright is not automatic. It had to be earned. The firstborn qualified for the birthright by virtue of being the oldest. But the firstborn does not get the birthright unless he merited it.
Perhaps the rabbis were on to something by defending an anachronism. What defines who we are should not be the attitude that “others owe me” but that “I owe others.”