ThirdWizard said:
Without specifics, it will be impossible to know, and it will be entirely setting dependant.
Are trolls nearby in the Swamp of Horrors? Are they on the other side of the world across an ocean and no one the PCs have ever met has actually seen one? That's going to change how its approached.
My point is that you are assuming that if knowledge is more remote than second-hand, it will be inaccurate. This is based, in my view, on a certain perception of premodern people that, while popular, is not one I share.
But, I don't see how it applies to ooc talking for in character things, especially combat. Having an understanding of the workings of the physical sciences isn't going to mean you you always see the flanking opportunity, or that you'll remember what the tatoo of the assassins of the silver flame looks like. I think you're going to have to explain to me what you mean a bit more before I understand what you're trying to get at.
Obviously I'm not making myself clear so I'll give it another shot. Forgive me if I seem pedantic or condescending here; I'm just trying to make sure my third attempt at stating this isn't another failure.
1. When people think about fantasy settings, they imagine them like pre-modern terrestrial societies with the addition of magic, be they medieval or ancient.
2. When people imagine individuals living in ancient and medieval societies, they tend to, thanks to modern popular culture, imagine such people as having inaccurate ideas about their world and its physical laws.
3. People therefore assume that the average person in a D&D society goes around with a bunch of erroneous ideas about the world around them and its physical laws.
4. People play D&D on the assumption that, unless the rules state otherwise, as in the Knowledge (*) skills, characters in D&D worlds will have inaccurate ideas about their universe's physical laws and data outside their firsthand experience.
5. For the above-stated reasons, people assume that characters routinely misjudge how flanking, attacks of opportunity, etc. work because, unlike their players, they don't have a handle on the physical laws of the universe they inhabit.
I would suggest that, if you are engaged in combat routinely and if it is your
job, as it is the job of most adventurers, even though you will not comprehend the rules of the physical universe in an academic sense, your powers as an observer will allow you to apprehend, even if you don't consciously know it, how attacks of opportunity work. If something (a) always works the same way, (b) is your job, (c) is something you practice a lot and (d) is something the knowledge of which your life depends on, I just don't buy that you will understand it less than someone whose job it is not, who practices it little and to whose life it is irrelevant.
It makes zero sense to me for your average adventurer to have less
practical understanding of the physical laws governing combat less than your average D&D player.