|"I Love Learning Torah"|
Socrates, the Greek philosopher, is known to have first concentrated on natural studies, trying to employ rationalism to discover the true forces and causes of all that happens in the world. He felt he disproved the existence of the Greek pantheon, but became stuck when he got to basis of real causality, why things must happen as they do, what forces cause and drive the basic injustices and unpredictabilities he saw each day. He therefore turned from biology to pure thought and philosophy and focused on ration and logic for the rest of his life. He simply could not come up with a reason why lightening should strike where it does, why the wicked sometimes seemed to prosper, why things must be as they are; yet he felt his cosmology was incomplete without that full understanding.
I mention Socrates because I am going to discuss a variety of opinions among commentators as to the question of why the Jews descended to Egypt and slavery. They were already G-d's chosen people, Am Yisroel. They were living in Canaan. What reasons and forces required that they all go down to Egypt, become enslaved, be redeemed, wander the desert, and go to war to retrieve their rightful homeland? The necessity of this occurring has been discussed by many, it's not a trivial question at all.
Ramban says this occurred because Avraham went down to Egypt himself, without being so commanded by G-d; and moreover by doing so he endangered the tzaddekes Sarah even more than himself. Therefore Hash-m had decreed his descendants should endure Egyptian exile.
Abarbanel says rather that the 10 brothers who sold Yosaif brought the Egyptian slavery on the people. They sold him to slavery, they cast him into a pit, and his pain was at their hands morally. Therefore the people were punished middah-k'neged-middah.
In Nedarim is teaches three reasons related to Avraham again; that he drafted talmidai chachamim to war to free Lot, that he did not accept the promises of inheritance G-d gave him at the bris ben habesarim, and that after the war of the five kings and four kings, Avraham allowed to Sdomim to return home rather than keeping them near him and teaching them to give up idolatry.
Last week I heard Rabbi Jeffrey Fox give another answer in a shiur. He cited the Rambam, Mishneh Torah, Laws of Idolatry. Rambam states that simple reason and logic, as displayed by Avraham in his youth, reveal the obvious truth of G-d. All you need is the basic human ability to think (which Socrates, Plato, and then Aristotle extolled in Greece) to see that G-d must be. The people knew this, but were led astray over time to idolatry all the same. When Avraham was 40 years old, he came to fully understand the logical truth of G-d, and it was then that he condemned idolatry and began to fight against it; after this, he came in loving contact and direct communication with G-d. While we frequently say that the Patriarchs followed the whole Torah, Avraham's religion, that which he taught, was not the specifics of how to wash pots to maintain kashrus nor exactly how an individual must put on tefillin. It was the uniqueness, perfection, and oneness of G-d.
Avraham wrote this down and transmitted it to his son Yitzchak, who of course gave instruction to his son Yaakov. Yaakov commanded that the descendants of Levi must continuously learn this so it would never be forgotten.
When the Jews descended to Egypt, though, eventually while surrounded by idolatry they turned to it (except the tribe of Levi). Quoting from the translation edited by Rabbi Isadore Twerski, "The children of Jacob returned to the mistakes of the nations, and to their straying from the true path. Out of love and out of keeping the covenant made with Abraham, G-d sent Moses our Teacher, chief of all the Prophets. Since Moses professed and G-d chose Israel as an inheritance, He crowned them with commandments, and made known to them the way to worship Him…."
Look at the above paragraph carefully. According to Rambam, if the Jews descended to Egypt because of some base mistake made by Avraham Avinu, all the same the result is astounding. The fact of their going to Egypt and descending into idol worship made possible, made inevitable, the giving of the actual Torah and its halacha. Had the Jews not gone down to Egypt, Judaism would be a completely different faith in practice, based not on a G-d given Torah but rather on almost Socratic principles of reason. The Torah is our minute-by-minute connection with G-d himself, it allows us to redeem ourselves spiritually at almost constant opportunities through the rewards of performing the mitzvahs. If Avraham Avinu erred and caused his descendants a few generations later to be sent into Egyptian slavery, out of that we received national redemption.