The idea that psychological tension is a result of divided self has been the topic in many forms in both psychological and sociological. Who I am, who I want to be, who I should be, and of course who I am to myself may be very different than who I am to you.
It appears that animals do not have it. When an animal does something no matter what the results they go on to the next thing, learning whatever they can from the previous experience free of regret.
But people are different. We do something and we have thoughts about it. Sometimes its positive—being self critical and asking how could I have done this better? becomes a learning situation. It can also be negative, a regret that never goes away—extreme negative self criticism can become a psychological strategy to defend your own self defeating behaviour.
For many in psychology the divided self , or the inability to deal with it is the root of psychological problems. Both Hegal and Marx believed that this divided self and the ways individuals resolved it provided the energy for change in the structure of society. And for Marx communisim was the resolution of those social forces which manifested themselves into the divided self of society, i.e. classes, i.e. as return to the Garden to Eden.
Whatever this divided self is, it is to be human. The idea that we can live without it, i.e. live in the Garden of Eden again, are the dreams of utopians and the promises of pop psychology.
I have subtitled this “The Divided Celph” because it seems to me that try as we might to understand this better, the relationship between social and biological, nature and nurture, is something we may never understand. Watching the behaviour changes in my mother after her stroke in which she suffered physical damage and there were changes in her ability to behave as she used to and as a "normal" human being, I still see her divided inside, seeing contradictions in her own behaviour, having feelings about them and struggling to llive with them, sometimes finding hope, sometimes being depresssed.