Having left Avraham with their hopeful message of life and the promise of a new son, the angels sent by Hashem turn toward their new mission, one of death and destruction. But Hashem stops, almost as if reconsidering, and decides to “check with” Avraham before going forward with the plan (Bereishit 18:17). Hashem's tone seems more informative than anything else, but Avraham takes the notice of Sedom's imminent destruction as an invitation to debate. What follows is a fascinating exercise in negotiation and the power of righteousness over evil.
Some kind of exchange between Hashem and the angels sent to perform the unenviable task takes place, as Hashem provides a way out for the people of Sedom: “I will go down and see if they acted according to the complaint, and if not, I will know” (18:21). While Hashem sends the angels on their way with that proviso, Avraham decides to try to head things off at the pass and immediately starts negotiating. The verb “VaYigash,” a particularly dramatic and tension-filled term reserved for moments of great danger and import, is used (as in Yehuda's use of the term in the eponymous Parasha). Avraham boldly stands before Hashem to make his case, not waiting for an invitation.
And what is the logic Avraham attempts to use to gain mercy for the inhabitants of Sedom, now that he knows Hashem has considered the possibility of letting them go? He plays a numbers game. Is the death of evil men worth the destruction of the righteous men who may live alongside them? An old philosophical idea states that the needs of the many outweigh the needs of the few. Avraham attempts to go the other way, claiming that a tiny percentage should earn mercy for a much larger whole. For such is the power of the Tzaddik: his single candle can light the darkness of thousands.
Hashem's almost sarcastic answer makes it clear (18:26) that He does not expect to find such a deserving group, though He finds no fault with Avraham's math. Avraham, realizing the implication of Hashem's response, believes it to be a matter of scale. So he employs a paradox: if a man has $100,000,000, then everyone would describe him as rich. But what if he lost one penny? Would he still be rich? We would all agree that he would. What if he lost two pennies? Or three? Which penny would turn him from rich to poor? Where is that precise line? Such is the cleverness of Avraham's argument: he attempts to force Hashem, as it were, to precisely define terms of righteousness vs. evil, in the mathematical sense, and to justify His description of Sedom as evil.
Does Avraham know that his attempt, like Sedom itself, is doomed? Does he think that Hashem allowed him to “overhear” the plan specifically to permit Avraham the opportunity to convince Him otherwise? While guessing Hashem's motives is difficult, guessing Avraham's is easier. While Avraham stopped pursuing his numbers game once he hit the figure of ten, he may not have been discouraged: he had wrung a commitment out of Hashem. Even as small a number as ten could have saved such a large population.
But of what use was such a promise? Surely Avraham knew, firsthand, how evil and deserving of destruction Sedom and her sister cities were. Surely he saw the need for the end of their influence. While Avraham may have failed to save Sedom, he secured something far more powerful for his own, and our, edification: the knowledge that, in Hashem's eye, few may outweigh many. His own son was about to be born, and the stage was being set for a drama that would unfold over the next four hundred years, ending with Bnei Yisrael in their own land and in control of their own destiny. But Avraham must have seen the hard times ahead, and he surely knew the hardships they would endure. After all, Hashem Himself had told Avraham of the travails that awaited Yitzchak and his descendants (15:13-16). Perhaps he wondered if his descendants would have trouble keeping their faith, as his own wife had when she heard a seemingly bizarre prediction earlier in the Parasha. Perhaps Avraham realized that in the course of their hardships, his descendants would now have a critical trump card: no matter how deep they might sink, no matter how far they might fall, a small number of believers and righteous people may bring them back from the brink. And it is this promise, more than any other, that took us through the darkest times of our history, when all hope seemed lost and nearly everyone strayed. There were always those few who refused to succumb to the despair, the disbelief, and brought us all back to Hashem.