Post History

To my reading, the discussion that follows makes it clear that the rabbis were wrong to excommunicate Rabbi Eliezer.  Rabbi Eliezer's excommunication is followed by various disasters, including the death of Rabban Gamaliel (who headed the Sanhedrin that excommunicated him) at the hands of heaven.

Some years ago I attended a talk by [Rabbi Danny Schiff](https://jfedpgh.org/schiff?no_redirect=true), which I [wrote about](https://www.cellio.org/blog/2016/oven-of-achnai) at the time.  I'm drawing what I say here from that talk; I searched for better written sources to support R' Schiff's argument but didn't find them (at least in English).  He argued that the other rabbis were concerned that Eliezer, by appealing for an answer from heaven instead of following the process of deriving law, could not be trusted in his other rulings either: if he didn't follow the process here, why should we assume he followed it elsewhere?  Thus, they sought to remove him from authority so he couldn't cause others to go astray through his incorrect methods.  My own interpretation is that the goal was good but the methods were overzealous and without regard to the harm they did, and that's why the disasters followed.

It wasn't merely about disagreement; as you noted and as our sources make clear, disagreements over the law happened a lot, with the houses of Hillel and Shammai being the most prominent.  But those disagreements arise within the system, not by stepping outside of it.