Yesterday, we discussed the question as to why Yaakov, upon returning to Canaan, first settles in Shekhem, before proceeding to Beit-El, where he had promised to establish a beit Elokim, and before reuniting with his father in Chevron. As we saw, Rabbi Menachem Leibtag, in his internet shiurim (http://tanach.org/breishit/vayish3.htm), suggested that in truth, Yaakov settled in Shekhem only after erecting a monument in Beit-El and visiting his father in Chevron, and the Torah's presentation of the sequence of events does not follow chronological order.
Among the advantages of this bold theory is that it results in Shimon and Levi being at an older age at the time when they took up arms against the male population of Shekhem. Let us try calculating how old Shimon and Levi were upon Yaakov's return to Canaan. Recall from Parashat Vayetze that Yaakov worked a total of twenty years for Lavan before returning to Canaan (31:41), and he married Leah after the first seven years (see 29:20-25). Thus, even if we should assume that Leah conceived with her oldest son immediately, and bore Shimon and Levi – her second and third children – very soon thereafter, Shimon and Levi could have been no older than eleven or twelve, or so, when Yaakov left Lavan's home thirteen years after his marriage to Leah. According to Chazal (Megila 17a), Yaakov spent a year and a half in Sukkot (see 33:17) before crossing into Eretz Yisrael, and thus Shimon and Levi were approximately thirteen years of age when Yaakov returned to his homeland.
It seems difficult to imagine, Rabbi Leibtag contended, that two boys of this age would be capable of waging the kind of battle in Shekhem that Shimon and Levi waged to avenge their sister's rape. If, however, we claim that the incident of Shekhem occurred several years later, after Yaakov journeyed to Beit-El and then to Chevron, Shimon and Levi are in their late teens or so at the time of their assault on Shekhem, an age that far better suits such a bold and violent measure.
What more, this theory also helps explain Shekhem's attraction to Dina. Dina was Leah's seventh child (see 30:21), and the Torah records a gap between the births of Leah's fourth and subsequent children (see 29:35). Thus, Dina could have been born no earlier than the eighth year or so of Leah's marriage to Yaakov, or five years before Yaakov's return to Canaan. If Yaakov settled in Shekhem just one or two years after leaving Padan Aram, it would be hard to explain Shekhem's lustful desire for Dina, who was all of seven years of age, at most. Once we explain that Yaakov spent several years in Beit-El and Chevron before settling in Shekhem, Dina becomes a young teenager at the time when she "went to see the daughters of the land" and fatefully caught Shekhem's attention.
Of course, this theory must provide some explanation for why the Torah would arrange the events out of chronological sequence. Rabbi Leibtag suggests a number of possible reasons, the simplest of which being that the Torah sought to combine Yaakov's experiences in Shekhem into a single narrative. Before the story of Dina's capture by Shekhem, the Torah tells of Yaakov's purchase of a plot of land outside the city, where he also erected an altar to God (33:19). Rabbi Leibtag suggested that Yaakov made Shekhem his first stop in Canaan to follow in the footsteps of his grandfather, Avraham, who first stopped in Shekhem when he arrived in Canaan and erected an altar at that site (12:6-7). Yaakov's purchase of a plot of land was likely an investment made in anticipation of his future, permanent settlement in the area. The Torah perhaps wished, in the interest of clarity, to combine all of Yaakov's Shekhem-related experiences into a single narrative, and therefore presented the story of Dina immediately following the account of Yaakov's purchase of land outside Shekhem.