The real reason
why Rabbi Yehudah the Prince requires five judges is because in “...whomever the judges condemn...”
the word “condemn,” ירשיען is plural, which means two judges. Another
two judges are mentioned below, and since the court needs an odd number
of judges to be able to rule by majority, the total is five.
The Sages, however, say that since the word “condemn” ירשיען is written
defectively, without an usual letter vav ירשיעון that one would expect
for plural, it means one judge. Therefore, their count is three judges.
The basic argument here is whether the pronounced form of the word
(Rabbi Yehudah) or its written form (Sages) is more important. Other
arguments hinging on the same “written or pronounced” premise include
the number of blood applications of a sacrifice needed for atonement,
the number of walls in a sukkah, and the amount of blood from two
corpses that creates ritual impurity.
Art: Jean Changenet - Three Prophets