"If eight couldn't save the world, certainly eight couldn't save one city." Why not?

Question

Rashi to Bereishis 18:32, explaining why Avraham only bargained for 10 and no less:

אָמַר דוֹר הַמַּבּוּל הָיוּ ח', נֹחַ וּבָנָיו וּנְשֵׁיהֶם, וְלֹא הִצִּילוּ עַל דּוֹרָם; וְעַל ט' עַל יְדֵי צֵרוּף כְּבָר בִּקֵשׁ וְלֹא מָצָא

He said, "The generation of the Flood had eight [righteous people] - Noach, his [three] sons, and their [altogether four] wives - and they were unable to save their generation." He did not ask for nine plus Hashem, because he already asked that [when he asked for 45 to save the area].

Why is this true? Maybe eight (nine) have sufficient merit to save a city, but not the entire world. If the argument went the other way, I could hear that, but the way it's written, it seems backwards.

This related question asks why Lot was successful with just four, while Avraham wasn't able to argue that. While it's a similar question, what I'm asking is that Avraham's own logic doesn't seem to make sense - the reason he has not to plead further seemingly isn't a valid argument.

Answer 1

1) The simple answer is that the 8 righteous people by the flood didn't save the world, or any part of it.

If Abraham could point to the flood history and say that the waters washed away everything except downtown Akkad, then you would expect him to try and find 8 decent Sodomites to save a city. However, since the 8 righteous by the flood saved no one at all, Abraham dropped that argument.

2) The OP argues that if 8 could not not save a world, then maybe they could at least save a smaller amount, like a city?

I would argue just the opposite. If a mere city should be destroyed as wicked, but the rest of the world is preserved, then why should that city be spared due to merits of the righteous? Maybe its a special exception to justice, to invoke the merits of the righteous when saving something big, like the entire world? Who says that justice would allow mercy when only a town is at stake?

3) Finally, check verse 29 with Rashi. Since your question is against Rashi, we can look into the previous Rashi to see where he is coming from here.

Rashi says that Abraham's argument for finding 40, 30, 20, and 10 righteous would only save 4, 3, 2, or 1 town respectively.

Also, Abraham never asks that the righteous around the world should help Sodom survive.

We see from here that Rashi understood that Divine Justice was viewing each individual Sodomite town, as its own private world. Each town was treated as trying to save a whole world, not just a town. Therefore, Abraham could compare the 8 righteous of the flood and their world, to one town in Sodom.

I hope this helps. :)