Realism???

After todays lecture on 'Realism', i have some ... thoughts. although i understand the point of realism, i can't really agree with it 100%.. and I'll tell you why. The whole aspect of realism is to "represent reality within a film", but who is to say exactly what reality is? because reality is within the eyes of the beholder, everyone perceives reality in a different way. for example, someone with a "mental disorder" such as Alzheimer's or anxiety disorders or Psychotic disorders involving hallucinations, drug addicts, alcoholics i could go on and on and on, my point is that these people obviously see reality differently than say you and me, who's to say that you and me don't see reality different. because if you think about it... could people having separate opinions technically be classed as seeing reality differently? or even someone not being affected by the cold as much as the person next to them is someone seeing reality differently than someone else. So really if you think about it, isn't a realist film... or a film representing reality, really just seeing reality as the filmmaker see's it??