Sometimes the Gemara provides not one but two different justifications for a particular practice. In many of these cases, the Gemara doesn’t prefer one over the other, giving the reader (or later legal authority) the ability to rely on either.
You might suppose, then, that it doesn’t matter which justification you choose. As long as you know the rule, you can ignore the justification. But the Gemara is certain that it does matter — because there is always a boundary case.
An illustrative example appears on today’s page:
Priests had to be in a state of purity in order to fulfill their duties in the Temple. Each day, the shift manager would stand those who were impure, in full view, by the eastern gate. Now the Gemara asks:
What is the reason that they did not simply send them home without making them stand at the entrance to the eastern gate?
It depends who you ask. Rav Yosef saw this as a punishment — to embarrass those who were not meticulous enough to remain pure for their shift in the temple. (Our second case of intentional embarrassment in as many days!)
Rava, on the other hand, saw this as a positive move — standing the priest publicly at the gate demonstrated that a priest’s failure to serve in the Temple was due to ritual impurity (which happens, no big deal) rather than failing to show up for work. In other words, the goal is to make clear that they couldn’t serve because they were accidentally impure, not because they chose to skip out on serving God in order to, say, go to a paid job.
So, does the reason for this procedure of standing impure priests at the eastern gate matter? Does it make a difference if we agree with the logic of Rav Yosef (embarrassment) or Rava (approbation)?
The Gemara explains that it does matter through two illustrative cases. The first is the case of a pampered priest who never works to earn money. In this instance, no one would ever suspect that the priest is avoiding Temple service in order to go to work. So Rava (who does not seek to embarrass impure priests) would not require him to stand at the eastern gate to prove that he wasn’t at work. After all, he never goes to work anyway. Rav Yosef, however, would still want to embarrass him for becoming impure when he was scheduled to work in the Temple, so Rav Yosef would require him to stand at the gate.
The second case involves a priest who makes rope for a living. Making rope, you see, was so unprofitable that no priest would skip out on Temple service in order to do it. And so, Rava would not require a rope-making priest to stand at the gate. Rav Yosef would, however — his policy of embarrassing impure priests still applies.
Rav Yosef’s policy of standing impure priests at the eastern gate in order to embarrass them turns out to apply more widely than Rava’s policy of standing impure priests at the eastern gate to prove that they showed up for work — as these two boundary cases show. Therefore (drumroll, please) it does matter which justification you choose.
If this sounds to you like the Talmud is splitting hairs, you are not alone. It is true that in almost all cases choosing Rava’s reasoning over Rav Yosef’s or vice verse makes no difference. However, according to the Talmud, if two rabbinic opinions have been preserved, there must be some case in which the choice of reason makes a practical difference. In this case, it’s two. The Talmud is committed to uncovering those cases, even if it must split a hair or two in order to do so.