All these things that I have done

"Although it is generally true that people say what they mean and mean what they say"

Are you allowed to put a sweeping general statement like that in the middle of a paper on medical ethics?! I keep being derailed from my reading by stuff like this. There's also

The common morality contains moral norms that bind all persons in all places; no norms are more basic in the moral life … [it] comprises all and only those norms that all morally serious persons accept as authoritative.

I can't decide whether this is so restrictive as to encompass nothing or merely a circular definition which basically boils down to norms that I and people who agree with me (and are therefore morally serious) accept. Thoughts?