From the Greek: psukhē(psyche) meaning soul... that which makes a person that specific person, rather than someone or everyone else.
1) "Logical" as determined by a psycho.
2) The processes of the human mind, not being entirely logical, often involve a psychotic component. Hence, the combination of "psycho" and "logical" is necessary. The psychotic component is often dominant in clingy ex-boy/girl friends.
2) Guy 1: Dude, the way Lauren operates is not logical.
Guy 2: Yeah, but it is psychological.
Guy 1: Don't you mean psychotic?
Guy 2: Yeah, that too.