Japanese avoid arguing, which is why Japanese politics is so lifeless. But if you are determined to offer an alternative to the other fellow's point of view, after he has made a statement you find questionable instead of confronting him head-on, you should first say so desu ne, which means "Ah, that's certainly true." Only then can you proceed to chip away at his position.
(I say "he" here because Japanese women are not inclined to argue outside the home at all, oh no.)
- Amelia LaGordo