By Rabbi Joshua (midrashically known as The Hoffer) Hoffman [z"l]
Many years ago, when I was studying in Yeshivas Brisk in Chicago, Rabbi Aryeh Binah zt'l was a guest for Shabbos, and the Rosh HaYeshivah, Rav Aharon Soloveichik, zt'l, invited him to speak at seudah shlishis, in addition to his own talk, we were thus treated to what one student called a 'double dose' of Torah. Both speakers opened their remarks by quoting Rashi to the parsha, who begins his commentary to parshas Korach by saying that it is nicely expounded in the Midrash Tanchuma. The obvious question is did Rashi mean to suggest that other parshas are not nicely expounded in the Tanchuma? Rav Aharon explained Rashi to mean that while, in other parshas, the midrash expounds only a few Rav Binah explained Rashi differently. He said that Rashi meant to say that the Tanchuma on Korach conforms with the simple meaning of the verses, the pshat, selected verses, the Tanchuma on Korach gives a through explanation of the parsha. The Tanchuma on Korach fits well into the plain meaning of the verses- the pshat- unlike midrashim on other parshas which do not fit that well into the pshat. Since Rashi's stated goal in his Torah commentary is to explain the pshat, or, sometimes, instead, to bring midrashim which conform to the pshat, he is telling us that the Tanchuma to parshas Korach fits this criterion.
Rav Moshe Sternbach, in his Ta'am Va-Da'as, asks a curious question on our Rashi. Why is it, he asks, that Rashi, after extolling the Tanchuma for its treatment of the verses in Korach, does not bring the Tanchuma in his commentary? This question is strange, because Rashi actually does bring the Tanchuma several times! However, I believe that Rabbi Sternbach's answer is very insightful, and by rephrasing his question, we can offer a different explanation of Rashi's comment on the quality of the Tanchuma on Korach, and benefit from Rabbi Sternbach's answer, as well. The question we may ask on Rashi is, why does he single out the Tanchuma on Korach as giving a thorough explanation of the verses, or as conforming to the simple meaning of the verses, when there are undoubtedly midrashim on other parshas that have one or both of these features, and yet we never find that Rashi says this about any other midrash? Rav Sternbach's answer is that while the Tanchuma finds reasons for Korach's rebellion as they emerge from the Torah's account of his rebellion, the bottom line is that when someone is engaged in a machlokes, in a controversy, there really is no reason for it other than that he wishes to be contentious. This is why, as I once heard from Rav Shimon Schwab zt'l, the Mishnah in Avos refers to the rebellion of Korach as the argument of Korach and his group, without mentioning Moshe. Rashi mentions that Moshe tried his best to quell the controversy, because he wanted to avoid the negative effects that machlokes has. Korach, on the contrary, was only interested in spreading the machlokes, and had no interest in what Moshe had to say. In a machlokes that is done 'leshem shamayim,' out of pure motivations, such as a dispute between Torah scholars on the parameters of a certain law, each side wants to hear what the other side has to say, so that between them they will emerge with the truth. In a dispute that is not leshem shamayim, there is no interest in finding the truth, because the dispute is fomented for the sake of the dispute. This was the real nature of Korach's rebellion against Moshe.
Seen in this light, we can reinterpret Rashi's statement on the Tanchuma as meaning that this midrash, by giving a plausible explanation of Korach's rebellion that conforms with the simple meaning of the verses, is explaining the parshas in a nice way - yafeh nidrashes. However, in this case, a 'nice' explanation does not reveal what is lying at the heart of the dispute. The famed Rav Gavriel Zev (popularly known as Rav Velvele) Margolis (1847-1935), rabbi of the Adas Yisroel shul on New York's Lower East Side, was once asked by a newspaper reporter if he had anything to say about Rav Shalom Elchanan Yafeh, a leader of the Agudas Harrabonim, with whom Rav Velevele answered that if one looks at the prayer 'emes veyatziv' recited after the morning Shema, he will see that it starts with the word 'emes'- truth- and then has about fifteen expressions until it mentions the word 'yafeh.' We see from here, said Rav Velvele, how far Yafeh is from the truth. A bit more seriously, Rav Chaim Yaakov Goldvicht, zt'l, founding Rosh HaYeshivah of Kerem b'Yavneh, used to say that when someone tries to give a 'nice' explanation of a Talmudic discussion, with everything falling neatly into place, it is most likely as far from the truth as emes is from yafeh. In a similar way, based on Rav Sternbach's comment that the Tanchuma's explanation of the motivation behind Korach's rebellion, while fitting in nicely with the pshat, is far from the true, underlying cause behind his actions