Shimon and Levi single-handedly Killed out an entire city because of immorality against Dinah their sister illustrating their character of anger, later Pinchas a descendant of Levi followed in his fathers footsteps and killed Zimri who was also engaged in an act of immorality using his anger in a postive way, the problem is the person he killed was Shimon's descendant. How did this happen they where both cursed by Yackov for their anger yet Levi developed positively and therfore Pinchas took revenge on the Sin and the other took part in the Sin. What caused this extreme parting of ways?
The Midrash (cited in my comments to YS' answer) gives the following analogy:
It's like two people who borrowed money from the king. One paid back his debt, and indeed later was able to lend to the king. The other not only failed to repay, but borrowed again.
Similarly, Shimon and Levi both "borrowed" (became indebted to G-d) at Shechem. Levi repaid his debt in the desert, when they responded to Moshe's call "Whoever is for Hashem, with me!" (after the Sin of the Golden Calf); and then they went on to "lend" G-d at Shittim (in a sense, Hashem now "owed them one"). Whereas Shimon not only did not make good on their earlier debt, but sank further into liability in the affair of Zimri.
However, the Midrash doesn't give a reason why they developed so differently. For that, we would need R' Yaakov's answer cited by YS.
Although I wonder about another possibility. Way back when, after the brothers' first visit to Egypt to buy grain, Yosef detained Shimon (Gen. 42:24). He had valid reasons for doing so (see Rashi there), but after all, that kept Shimon away from his family for probably several months or more (the time it took for the rest of the brothers to get back to Canaan, consume all of the food they had brought back, convince Yaakov to allow Binyamin to go with them, and then travel back to Egypt). Could it be, then, that this lost time (of being in the presence of the tzaddik Yaakov, or of the opportunity to perform the mitzvah of honoring his father) itself had a negative effect on him?
Reb Yackov Kamenetsky in the Emes LeYaakov answers to understand we have to see how history developed.That is while most of Klal Yisroel were slaves in Mitzrayim,Levi was free to learn Torah. It was the Torah values that allowed the Leviim to channel their zealousness in the proper way. By stark contrast Shevet Shimon never got to learn Torah.Therefore their zealousness had no torah values and therefore expressed itself in forbidden ways. Rav Yackov says: “When zealousness is guided and bound by the limits of the Torah then it will succeed…. But without guidance, boundaries, and the hanhagas haTorah it [zealousness] does not have the power to succeed and ultimately will remove the kanai from the world.”
YS cites Pinchas' killing of Zimri (Bamidbar chapter 25) as an example of Shimon and Levi's “parting of ways.” YS's question can be strengthened with further illustrations of the ambiguity and tension that seems to surround these two charcters. In Bereshit, Levi and Shimon are both severely reprimanded in the blessings of Yaakov at the end of his life:
Conversely, at the end of Moshe's life, Levi is praised whereas Shimon is completely ignored:
For Levi the words: “I will divide them in Jacob, and scatter them in Israel” is manifest by taking residence in the arei miklat, cities of refuge, distributed throughout the land of Israel. For Shimon, this meant being awarded a portion of land completely subsumed within the portion of Yehuda and then completely disappearing from the narrative history of the Tanach. The last time we hear from the tribe of Shimon in any narrative portion of Tanach is in the first chapter of the book of Shoftim. There, Shimon is involved in an act of terrible cruelty against the enemy king Adoni Bezek:
Many biblical commentators have addressed the development of the Shimon and Levi characters in the Torah. For example, YS gave an answer provided by Rav Yaakov Kamenetsky. Rav Kamenetsky's answer like many of the answers that are given to this question is obviously correct in the sense that the message it teaches is unambiguously a fundamental message of the Torah:
Furthermore, the distinction made by Rav Kamenetsky's between Shimon and Levi is conceivable assuming we take literally the Midrashim that Levi were learning Torah in Mitzrayim. However, I think a careful, literal reading of text suggests a different answer (for an analysis of the exegetical role of midrash see Appendix #1, for an analysis of Tanach begovah einayim, see Appendix #2).
Like the midrash cited by Alex in his answer, is is clear from the Torah that the pivotal point in the narrative where the tribe of Levi merit their status as workers in the Temple is the incident following the sin of the golden calf. There the Torah describes:
The Torah summarizes this event in the book of Devarim:
The incident with Shchem (Bereshit 34) cited by YS in his question, is the Torah's archetypal incident of morally ambiguous militarism. The text there strongly suggests that Levi and Shimon were justified in their massacre, yet Yaakov's “curse” at the end of the book, implies otherwise. (The blessings of Yaakov are further riddled with paradox considering that Reuven gets a very positive blessing despite the the Torah's horrifying testimony: “And it came to pass, while Israel dwelt in that land, that Reuben went and lay with Bilhah his father's concubine; and Israel [Yaakov] heard of it...” (Bereshit 35:22).) Apparently, the moral ambiguity is resolved after the incident at Har Sinai where Levi's militarism is vindicated.
In other words, the killing of Jewish people at Har Sinai was necessary to demonstrate that the killing of non Jews in Shchem was not an act of nationalistic fervor or xenophobic prejudice, but rather was done leshem shamayim, for the sake of heaven. I think the discrepancy that emerges between the character of Shimon and the character of Levi makes clear that when we are forced to defend ourselves against an enemy, we can do so in one of two ways. If arms are taken up in the name of militarism and blood thirst, the act is unacceptable, however if arms are taken up with a sense of moral obligation and koved rosh, it is praiseworthy. Shimon killed his enemies and tortured them unnecessarily, Levi was willing to kill people who were not his enemies and carry out his mission with a heavy heart. Shimon killed only when it was convenient for him, Levi was willing to kill when doing so was horrific and impossibly tragic. Shimon wanted to go to war, Levi did so when it was absolutely necessary and when the imperative was as unambiguous as it was at the foot of mount Sinai.
This I think, is the source of the zealousness that the Torah admires in Pinchas and this is an issue that needs to be brought to the fore today where, for better or for worse, questions of war and morality have suddenly become practically relevant.
The assumption of the midrash that the tribe of Levi was exempt from the slavery in Egypt and allowed to learn Torah is not at all obvious. The simple reading of text does not suggest that the Leviim had special treatment in Egypt and its unintuitive to say that the Torah was studied there since the Torah was only given to the Jewish people after the exodus from Egypt.
Assuming the inerrancy of the Torah and the significance of what Chazal have to say, is it somewhat unsettling when a midrash makes assumptions that are not explicit in the Torah. There are two methodological approaches to this situation:
The main difference between these two approaches is the question: how much time should be spent studying and resolving the simple reading of the Torah without taking on the additional assumptions of Chazal.
This methodological question is an explicit dispute amongst the Rishonim. A careful reading of the Rambam in Hilchot Talmud Torah, the laws related to Torah study, (1:11) makes it clear that he assumes like the second approach outlined above (see also his introduction to his commentary on the 11th of Chapter of Tractate Sanhedrin and multiple places in the Moreh). Alternatively, the position of Rabbenu Tam quoted in the Tosfot on Kiddushin 30a implies that he holds like the first approach outlined above.
In my analysis of this issue (and in Rav Kaminestsky's analysis as well), the character of Shimon is criticized. This is not a simple thing to do considering the stature of a biblical character like Shimon and his central role in Jewish history as the father of one of the twelve tribes. Whether or not it is desirable to criticize biblical characters relates to the highly controversial issue in Jewish thought called Tanach begova einayim. In my humble opinion and in the opinion of the Rabbis who taught me how to study Tanach, the criticism of biblical characters is inappropriate if it means passing judgment on people who we never met, we cannot understand and who cannot defend themselves against our claims. However, criticizing biblical characters is appropriate and is valuable if the goal of our criticism is exclusively to uncover the messages that the Torah intended we take from its narratives.