Foreshadowing
One of the most important ideas that the Rashbam develops is the principle of foreshadowing. According to this principle, when the Torah notes details that appear to be disconnected, extraneous, or anachronistic, it actually provides them in order to explain an event that comes afterwards.
It is possible to apply the principle of foreshadowing, not only to verses or fragments, but even to larger segments. For example, in the Rashbam’s introduction to Bereishit, he declares that the story of Creation interests us solely because it helps us understand the Ten Commandments.
From explanations similar to this, it arises that the essence of the Torah is the mitzvot, while the narratives are secondary; the stories appear in order to explain the mitzvot.
Peshat and Halakha
In his explanations of the halakhic portion of the Torah, the Rashbam employs the same method which he applies to the narrative portion of the Torah: the explanation of the verses without any reliance on Midrashic literature. This approach is difficult to apply to mitzvot because the binding halakha is not the simple meaning of the verse, but the interpretation of the verses as the Sages explain it. The Rashbam believes that one should adopt the views of the Sages for everything that relates to practical Halakha; however, the interpretation of the peshat and the halakhic midrashim can live under the same roof. What worth does peshat have when it does not fit with Halakha? One possibility is that the peshat reflects the ideal, while the derash deals with the real.
