Term for an inability to accept ideas that are outside the norm This one might need a bit of an explanation. I read a statement someone made a few months ago about the normalization of concepts in society. That is if you have ideas that don't exist within the range of socially acceptable opinion, people won't tend to understand or accept them, and so discourse is usually confined to that range.

So I'm wondering if there is a term for either:

An inability to accept ideas that are outside the norm of socially acceptable opinion.

OR

The phenomenon in general, where public discourse is usually limited by a range of what's acceptable.
At an individual level, a person that refuses to even consider an idea that goes against his or her existing beliefs would be called close-minded or narrow-minded. 

Intolerant and prejudiced can also be used, but intolerant tends to be applied when discussing religious or political ideas, and prejudiced when talking about racial relations. 

Conformist can also be used, and is a more neutral term. It's also a bit vague, so you'd have to specify which idea or range is being conformed to.

A public discourse limited to an acceptable range of subjects would limited to "safe topics". 

A person who can accept or generate ideas outside of socially acceptable opinions can be labelled a free-thinker. Depending on how far outside the norms the ideas are, the person and may be branded a "radical" or even "pervert" in order to indicate society or government's disapproval of the individual.