There is a strange debate preserved in tractate Berachot (folio 47, column 2) that asks a question most of us are afraid to ask out loud. Who, exactly, counts as an am ha'aretz — a person so unlearned that certain kindnesses may be withheld from him?

The rabbis could not agree. Rabbi Eliezer said the ignorant one is he who fails to recite the Shema — "Hear, O Israel" (Deuteronomy 6:4) — both morning and evening. Rabbi Yehudah said it is he who does not wear tefillin. Rabbi Azai said it is he whose garments lack tzitzit, the fringes commanded in Numbers 15:38. Others argued that even a man who reads Torah and Mishnah is ignorant if he has not sat in service before the disciples of the wise — for book-knowledge without a living teacher is knowledge on stilts.

Rav Huna refused to close the debate. "The law is as the others have said," he declared, and left the difficulty where he found it.

This open ending is itself the teaching: Judaism is afraid of any definition of ignorance that is too easy, because every definition becomes an excuse to look down on somebody.