Pirkie Avos 5:17. Any dispute that is for the sake of Heaven is destined to endure; one that is not for the sake of Heaven is not destined to endure. Which is a dispute that is for the sake of Heaven? The dispute(s) between Hillel and Shamai. Which is a dispute that is not for the sake of Heaven? The dispute of Korach and all his company.
This wisdom elucidates about what a ‘good’ conflict is. In order for a conflict to endure it must be for the sake of heaven. This means that the conflict is over what is acceptable to the Master of the Universe. The example which is given is the conflict between Hillel and Shamai, two of the most famous teachers of Jewish law. These two disagreed on many laws.
As the Crash Course in Jewish History link explains:
The schools of Hillel and Shammai are famous for their disputes in Jewish law. One of these concerned whether one should tell a bride on her wedding day that she is beautiful even if this is not true. The school of Shammai held that in this situation it would be wrong to lie. The school of Hillel held that a bride is always beautiful on her wedding day. (Talmud, Ketubot 16b-17a) The school of Hillel won the dispute. Indeed, Jewish law today almost always agrees with the school of Hillel.
The reason that the conflicts between these great sages were for the sake of heaven their controversy endures. The Talmud even relates the story of how Hillel and Shammai disagreed on the order of lighting the Channukah menorah [LINK]. I quote from that link:
These two academies played a very important part in our Jewish heritage. Each academy consisted of the students of either Hillel or Shamai. These two sages are amongst the earliest of the sages recorded in the Talmud. They maintained many opposing viewpoints, yet, argued with each other with honor and reverence. Many arguments are recorded in the Talmud. The argument presented herein is only one of many.
The Talmud in Tractate Shabbat relates that the academy of Hillel advocates lighting the candles as we know today, in ascending order. The academy of Shamai disagreed and advocated that we light the Chanukah candles starting with eight candles on the first night, then seven candles on the second night. This is in reverse order that we know today. The academy of Shamai advocated lighting the candles in descending order. Therefore, each succeeding night of Chanukah had one less candle than the preceding night.
The Mishnah goes on to describe what constitutes a conflict which will not endure. The conflict between Korach and his cohorts against Moshe, our teacher. As we read several weeks ago, one of the leaders of the jewish people felt that Moshe didn’t deserve to be the leader of the Jewish nation. Korach assembled a group of 250 men of reputation amongst the people. They mocked Moshe by bringing him questions which they considered proofs that Moshe didn’t really know the laws which Hashem gave him. See my commentary on Korach at this link.
Korachs conspiracy was a conflict based solely on Korachs own selfish pride and arrogance. He felt that if he could not have all the power then nobody, Moshe included, should have the power. Despite the entire nation knowing that Moshe was the one who brought them out, they started to feel as if they deserved more than what Hashem had given them.
The Mishnah illustrates that a conflict which results in learning and growing and searching for the truth, such as the conflicts of Hillel and Shammai will endure and be for the good of the world. Those conflicts of vanity and ego will not endure. When the conflict of Korach was over it was utter destruction for Korach and his perverted party. This kind of conflict was not for the betterment of the world and was not good in Hashems plan.
Hillel taught one of my most favorite Mishnas of Pirkie Avot. Chapter 1, Mishnah 12 reads:
“Hillel and Shammai received the transmission from them [the previous generation of scholars, of Mishna 10]. Hillel said: Be of the students of Aaron, loving peace and pursuing peace, loving people and bringing them closer to Torah.”
OU Description of Shammai : http://www.ou.org/about/judaism/shammai.htm
Discussion of Chapter 1, Mishnah 12 : http://www.torah.org/learning/pirkei-avos/chapter1-12.html
On Arguments : http://www.torah.org/features/spirfocus/arguments.html
Rabi Naftali Reich : Pirkei Avos Chapter 1 Mishnah 12 & 13 Video