We need fanatics. By keeping true to their ideological positions – whether by threatening to bring down the modern global financial markets or by banning vegetables for consumption because they contain microscopic bugs – they remind us of the power and importance of their ideas. Fanatics are very good as serving as embodied and visible reminders of the power of ideas. In their unbending idealism, however, they are not as good as leaders or dinner companions.

The rabbis of antiquity struggled with the fine line between fanaticism and a reasoned commitment that required negotiation with unpleasant material realities. In the well-known story of the destruction of the Second Temple, the Talmud ambivalently blames a Rabbi Zechariah ben Avkulus for provoking the Romans by not offering their sacrifices; the rabbis were willing to let slide a small blemish on the animal (B. Gittin 56a). Later in the same passage a radical opinion of Rabbi Akiva, apparently supporting armed resistance to the Romans, is reported but marginalized. Elsewhere, Pinhas is warily admired and condemned at the same time. The rabbis almost guiltily acknowledge the fanatical position as pure, but unworkable.

I recently came across a striking Talmudic legal passage that exemplifies this kind of reasoning. According to an obscure and slightly uncomfortable Mishnah, one “may not stable an animal in the inn of ‘idol worshippers’ because we suspect them of bestiality.” This immediately provokes a long discussion in the Talmud about whether non-Jews really should be assumed to engage in bestiality whenever given the chance. This in turn leads to a discussion of the “red heifer,” which is rendered impure if it was engaged in bestiality. If this is true, though, what about its mother? Shouldn’t we worry about its mother, and its mother’s mother, all the way back? After all, if one of them had been.. well, you know… then they should all be unfit to serve as red heifers. “To this whole degree, we are not worried,” the Talmud finally concludes (B. Avodah Zara 24a). We do not need to inquire back into the lineage of the animal. What we see is enough.

We don’t need the Talmud to highlight the tensions inherent in fanaticism. What is interesting about these rabbinic reflections is that in a sense the rabbis really were fanatics. Maybe better, a good number of them much of the time wanted to be fanatics; they scorned compromise and frequently looked askance at those who did not devote their lives to Torah study. But at the same time they realized the limits of their thinking. Fanaticism might feel good, but in reality it doesn’t work so well in practice.