I think my dad might be dumb. I'm really questioning my his logic.
Can you explain what that means?
I don't know why my dad does everything that he does, I guess that is just how he is.
Have you asked him about the thought process behind some things? I am sure it would be fine to ask him as long as you do so nicely.
His thought process is that he's dumb. I just explained that to you.
I'd caution that just because you don't agree with your father, that doesn't mean that he is dumb. Maybe just pick one thing and ask him about it, you might be surprised when you see that he has legitimate reasons for doing the things he does.