The Levi Yitzchak of Berditchev contrasts Korach's 'machloket' with legitimate disagreement, explaining that Korach's argument — 'all the congregation is holy' — contained a kernel of truth but was driven by ego, making it the paradigm of a dispute not for the sake of Heaven.
ויקח קרח בן יצהר בן קהת בן לוי ודתן ואבירם וכו' (במדבר טז, א). הנה הרמב"ן הקדוש כתב מחמת שהמרגלים ידעו שזה הדור לא יכנסו לארץ ישראל מחמת זה נתקלקל קצת האהבה אשר היה לישראל אל משה וזה גרם שחלקו והרהרו אחר משה ולכך נסמכו הפרשיות עד כאן תוכן דבריו. הענין, כי הנה היה דור המדבר ודור שנכנסו לארץ ישראל. והנה דור המדבר, הלשון מדבר הוא דיבור שפעלו הכל בדיבור, כי יש צדיקים אשר הם פועלים הכל בדיבור ואין צריכין לשום עשיה. ודור שנכנסו לארץ ישראל, מרומז על העשיה שהיו צריכין לעשות איזה פעולה ולכך יהושע כאשר נלחם עם ל"א מלכים היה צריך לעשות איזה מעשה עם הכידון והאורב אבל משה שהיה בדור המדבר לא היה צריך לעשות שום פעולה, רק פעל הכל בדיבור. וזה שכבש יהושע את יריחו הכל בדיבור עלינו לשבח כמבואר בדברי רבותינו ז"ל (ירושלמי מו"ק ב, ד) הוא מחמת שיריחו כבש בשבת. ומבואר בכתבי האר"י ז"ל שהשכל שיש להרב בחול יש לתלמיד בשבת, והיה בו אז השכל שהיה למשה בחול ומשה פעל הכל בדיבור ובזה הבחינה כבש יהושע יריחו בשבת על ידי הדיבור אבל בעי ושאר מלחמות היה צריך לפעולה. והנה תורת משה הוא כנגד הדיבור שפעל הכל אצל השם יתברך עם הדיבור, אבל יש לה התלבשות על ידי המדות גם בעולם העשיה כמאמר הכתוב (ישעיה מד, ו) אני ראשון ואני אחרון. והנה קרח כשראה שאותו הדור לא יכנסו לארץ ישראל לא היה מאמין בזה שתורת משה יש לה התלבשות גם בעולם העשיה. וזה שפרע לו הקדוש ברוך הוא מדה כנגד מדה ותפתח הארץ את פיה, הארץ הוא העולם העשיה להראות שגם בעולם העשיה יש לה התלבשות תורת משה. וזהו הרמז בן יצהר, לשון בהירות. בן קהת, לשון אחדות על שם הפסוק (בראשית מט, י)ולו יקהת עמים. בן לוי, לשון התחברות עיין שם. והפעם ילוה אישי, לרמז שקרח לא היה מאמין רק בעולם הדיבור שיש לו שלשה בחינות אלו ולא היה מאמין שגם בעולם העשיה יש התלבשות אבל באמת שגם בעולם עשיה יש התלבשות כמאמר הכתוב אני ראשון ואני אחרון: פירש רש"י נתקנא על נשיאתו של אליצפן בן עוזיאל. לכאורה אינו מובן למה לא חלק תיכף אחר שמינה משה רבינו עליו השלום את אליצפן. אמנם קודם גזירת מרגלים היו ראוים ישראל ליכנס מיד לארץ ישראל על כן סבר קרח שגדולת אליצפן לא יהיה רק זמן מועט דהא בזמן מועט יכנסו לארץ ישראל, מה שאין כן אחר גזירת מרגלים וראה שיגזור שיהיו מ"ם שנה במדבר אז קינא שאליצפן יהיה נשיא מ"ם שנה:
Numbers 15,1. “Korach, son of Yitzhar, son of Kehat, son of Levi, and Datan and Aviram took, etc;” [At this point there appears to me to be a major error in our editions when the author claims that Nachmanides wrote that the spies had been aware that the Israelites would not enter the Holy Land. According to my understanding of Nachmanides on 15,1 he refers to the people having been aware of this decree, seeing that the spies were dead already. Ed.] Nachmanides writes that seeing that the (spies) people knew that the members of their generation would not enter the Holy Land, the Israelites’ love of Moses had already been undermined so that the people would be more receptive to criticism of him. This is also the reason why this episode was written in the Torah immediately following the story of the spies. There had been several instances since the sin of the golden calf when many people had died without Moses having been able to prevent this, so that Korach felt that an attempt at insurrection could meet with broad support. Basically speaking, the generation of the Israelites who had left Egypt as adults was of a spiritual level that enabled them to perform the commandments by merely using their power of speech, i.e. prayer alone. The next generation was of a lower spiritual level, requiring action in addition to prayer. [Presumably the difference of the spiritual level of these two generations was due to the older generation having been addressed by G’d directly at the revelation on Mount Sinai. Ed.] The author cites as proof of this distinction the fact that Joshua when battling the 31 kings of the land of Canaan, had to perform some action with the javelin signaling to the ambush (Joshua 8,19) in order to secure victory. Moses, on the other hand, did not have to perform such actions, but accomplished his task by utterances emanating from his mouth alone. If you were to argue that Joshua conquered Jericho relying only on דבור, the power of speech, as pointed out in the Jerusalem Talmud Moed katan chapter 2 halachah 4, the reason for this was that Jericho was captured on the Sabbath, and the Ari’zal has pointed out already that the intellectual capacity of the Rabbi on a weekday is attained by his disciple on the Sabbath. Similarly, the relationship between Moses’ intellectual capacity and that of Joshua was like that of the teacher compared to the student. Moses had been able to accomplish everything he set out to do by relying exclusively on the power of the word. [Perhaps Moses’ failing to speak to the rock when commanded to and striking it instead, represented this desecration of G’d’s name in public that G’d accused both him and Aaron of. Ed.] Both at Ai as well as during subsequent battles, Joshua had to employ other parts of his body in addition to the power of speech. The Torah Moses presented to the Jewish people reflected the power of the word used by G’d when He created the universe; however, in common with other forms of energy emanating from G’d’s essence which had to be “screened” in order that their impact would not prove harmful instead of beneficial, even in our world of the עשיה, where matter appears as if it is “real,” this is so only because what we see with our three-dimensionally oriented eyes has already undergone such a process of being screened before we see it. According to our author this has been alluded to when the prophet Isaiah 44,6 quoted G’d saying: אני ראשון ואני אחרון, “I am no different at the end from the way I was at the beginning.” [The usual translation, is, of course: “I am first and I am last,” but I changed it to fit the author’s interpretation. Ed.] G’d meant that if He employed “screens” to protect us from His outpouring of Divine energy at the beginning of creation, He did the same when He came to the final stage of His creative activity, i.e. earth and man. The form that these “screens” take in our material world is the attributes through which we try to understand the nature of the Creator, His מידות. When Korach had realized that the generation of which he was a part would not be granted residence in the land of Canaan, he no longer accepted Moses’ Torah as something to be understood as having been “screened” by G’d before He entrusted it to us in the format that we are familiar with. When G’d punished Korach by making the earth open its “mouth” to swallow him and his followers alive, He actually paid him back מידה כנגד מידה, “tit for tat,” seeing that Korach had refused to believe that the earth as we see it is not the “real thing;” he was taught at the last moment of his life how wrong he had been, and that the earth had hidden dimensions he had never dreamed of. This has all been hinted at when the Torah listed as Korach’s antecedents, i.e. Yitzhar-alluding to brightness, light, Kehat- and Levi. The word יקהת alludes to “unity” as we know from Genesis 49,10 where Yaakov blessed Yehudah by saying that the other tribes would rally around him. The word לוי derived from ילוה, when his mother Leah, at his birth, expressed her hope that this son would be the cause of her husband spending more time with her; (Genesis 29,34) When looking at the three names together, they suggest that Korach only believed in the world of the power of speech, the world that we know as the three-dimensional world, and could not believe that behind what we see with our physical eyes there is hidden another dimension, one which makes it far easier to relate to the home of the Creator and the army of angels with whom He has surrounded Himself. [some of these words are mine. When someone insists on believing that the world we see is all there is in the universe, so that physical death is the end of all life, he has made the beginning of life equally irrelevant. Ed.] The words of Isaiah 44,6 are therefore most important if we wish to understand G’d’s actions in creating different sections in His universe. In his comment on the words ודתן ואבירם, Rashi adds that whereas these members of the tribe of Reuven had been angry that their tribe had not been accorded the privileges due to the first born, i.e. their founding father Reuven, Korach was angry at not having been appointed as the leader of Kehatites, rather than Elitzafan ben Uzziel whom Moses had appointed at G’d’s instruction. (Compare Numbers 3,30). Rashi explains that Korach felt slighted, feeling that since he was the first born son of Yitzhar who was the second son of Amram, this position was rightfully his, seeing that Elitzafan son of Uzziel was the son of someone junior to his father. Our author wonders that if Korach’s dissatisfaction had dated back to these appointments described by the Torah in the third chapter of Parshat Bamidbar, why had he not complained at that time? Our author answers this by reminding us that at that time, before the episode with the spies, when it was assumed by the people that they would all enter the Holy Land and secure their ancestral heritage there, the position of tribal head or even that of head of one of the three sections of the Levites, would prove to have been a very temporary position, as entry into the land of Israel was expected to take place within less than a year. Now that they were condemned to spend 40 years wandering in the desert this position carried with it far more importance. Korach’s jealousy therefore had been aroused at this time.