There’s nothing wrong with having an intelligent debate with anyone, just make sure you bring your intelligence with you—ignorance isn’t always blissful.
The ignorant love to argue.
They don’t do it because they have anything relevant to say but, rather, because they want to feel relevant. Don’t give them the satisfaction of, unnecessarily raising your ire. It’s not worth it, for one, and it usually won’t get you anywhere—for two.
The best thing to do when you’re faced with a “debate” with a person who has left his/her intelligence at the door, is to keep walking. However, if you, just for kicks, want to engage in a conversation with a person who has offered an ignorant perspective to an otherwise intelligent round of chit-chat, then check your motivations. Do you, 1) only hope to educate them or 2) feel a need to strut your superior knowledge on a particular topic?
If the answer is number one, then good for you and bless your efforts. No change was ever made without first taking a step into the fire. However, if your motive centers around number two, then it’s possible you might be just as ignorant as they are—so check yourself first—no one likes an arrogant S.O.B.