"Rav Chaim Can't Be Wrong!"

In a recent argument with someone about charedim avoiding serving in the IDF, my disputant brought what he thought was a dispositive proof for his position:

Torah is the ultimate Divine source of wisdom

Rav Chaim Kanievsky knew the entire Torah

Rav Chaim held that yeshiva students shouldn’t serve in the IDF

QED!

You might wonder why he mentioned Rav Chaim Kanievsky in particular. (And it is actually somewhat ironic, because Rav Chaim himself served in the army, back in 1948, albeit doing little more ...