"Common sense" can sometimes be misleading. We, as a species, are all capable of different degrees of delusion, hard-wired into our brains. "Common sense" is best accepted when it is objectively and scientifically verifiable.

We are all ignorant about something but to argue is often to question what is accepted and that can be interpreted by authoritarian types as ignorance.

The antidote to rigidity is to keep an open mind so long as your brain doesn't fall out.

I don't think I have to keep an open mind, however, about slavery, fascism, abuse or war. I'm opposed to all of them and haven't heard any reasonable arguments that could cause me to change my mind.