Jermaine Jackson -- Michael Jackson Would've Set Justin Bieber Straight

Michael Jackson and Justin Bieber would've been tight ... so says Jermaine Jackson ... but he also thinks MJ would have put the Biebs in his place.

Our photog spotted Jermaine at LAX yesterday, and he told us he thought MJ and Biebs would have probably made some music together, but more importantly ... Michael would have "spoken to him like a father figure."

Interesting insight ... if you can strip away the fact that MJ hanging around a 14-year-old Bieber could be viewed (certainly in hindsight) as SUPER creepy.