Madness
Being human demands that each of us maintain a balance between the P-world of the individual and the communal world of ideas. Both are "biological" phenomena in the broader sense, and "we" are constituted by both. Our selves are balanced precariously, identifying now with the pain in a specific leg, and now with the shared adulation at a sports victory. But that balance can go wrong, and when it does, we do not have useful medical terms for dealing with it. For our, Western medicine, is a medicine of the body alone.
Psychoanalysis was a brave attempt to understand our selves. It was an early attempt, but it stuck its neck out further than any mainstream psychology dared. Looking at ourselves as only partly constituted by P-worlds provides us with another vocabulary which may prove useful.
This is a very incomplete sketch. I will make a more serious effort to relate the P/R distinction to psychiatry in the near future.