Among the important - and, very often, the most controversial - issues that arise when studying the stories of our avot and imahot (patriarchs and matriarchs) is the possibility of criticizing their conduct based on a careful reading of the verses. Is a scholar entitled to point to a moral or religious flaw in one of our avot or imahot based on his careful and thorough analysis of the text, or must we limit our critique of these saintly people to that which appears explicitly in the text and Midrashim? We will demonstrate one example of this debate that expresses itself in a question concerning one verse in Parashat Toledot.
When famine strikes the land of Canaan, Yitzchak, following the example set by his father many years earlier, heads towards Egypt. But God appears to him and forbids him from leaving Canaan. At this point, God bestows upon Yitzchak the blessing of a great nation in the land of Canaan: "I will make your descendants as numerous as the stars of heaven and give to your descendants all these lands… because Avraham obeyed Me and kept My charge, My commandments, My laws and My teachings" (26:4-5). Surprisingly, God attributes His blessing to Yitzchak not to his own merits, but rather to those of his father, Avraham. Why did Yaakov not independently deserve God's blessing, but rather depended on the merits of his saintly father?
The Seforno interprets this as a subtle criticism of Yitzchak. Until this point, we do not find Yitzchak engaging in the "calling in God's Name," a phrase that appears numerous times throughout the story of Avraham, and which many commentators explain as a reference to proselytizing. Unlike Avraham, Yitzchak did not involve himself in the dissemination of monotheism and Godliness. He was therefore not independently worthy of establishing a large nation in the land of Canaan. The Seforno adds that later, after Yitzchak's banishment from Gerar, God reiterates His promise to Yitzchak and once again emphasizes, "because of My servant, Avraham" (26:24). Immediately thereafter, in the very next verse, Yitzchak indeed "calls in the Name of God." From that point on, the Seforno observes, Yitzchak experiences no more hardship from the Philistines or any other people, as he had until this point. In fact, the very next verse tells that the Philistine king Avimelekh initiated friendly, diplomatic relations with Yitzchak. During the course of their discussion, the Seforno notes, Avimelekh declares that Yitchak is "now the blessed one of the Lord" (26:29). The Seforno does not clarify his intent by making this observation, but presumably he means that only now that Yitzchak has begun his active involvement in preaching, he is independently blessed by God, no longer dependent on his father's merits. (This is the explanation found in the footnotes to the Seforno in the Torat Chayim Chumash, on 26:29.)
Rav Moshe Feinstein (Kol Ram, vol. 2, p.28) disagrees with the Seforno's approach on fundamental, ideological grounds. After the Talmudic era, he argues, no one reserves the right to make judgments regarding the conduct of our patriarchs - neither the Rishonim nor the Acharonim. Therefore, in the absence of any source in Chazal for such criticism, we cannot ascribe to Yitzchak this flaw of failing in his responsibility to teach and educate his contemporaries.
Rav Moshe therefore offers a different, more esoteric explanation for this verse. Chazal describe Yitzchak as an "ola temima" - a perfect burnt-offering, that had been placed upon the altar. Rav Moshe explains that just as an "ola" (unlike other sacrifices) is burnt entirely on the altar, and no meat is eaten by a human being, so was Yitzchak entirely spiritual. He represented absolute devotion to spiritual concerns. By contrast, Avraham and Yaakov represent the fusion between the two realms, the physical and the spiritual. When God bestows a blessing upon all of Am Yisrael, the descendants of the patriarchs, He must include both elements - the physical and the spiritual - in His blessing. Clearly, an entire people cannot survive on spirituality alone; a strong economic and military infrastructure is necessary for the nation to achieve its goal and realize its spiritual destiny. When proclaiming this blessing in Parashat Toledot, then, the Almighty must invoke the merit of Avraham, who represents the successful merging of these two realms, and cannot bless the nation that will emerge with the blessing of Yitzchak alone.