Fun Fact: Multiple personality disorder is not the same as schizophrenia.
http://en.wikipedia.org/wiki/Schizophrenia vs
http://en.wikipedia.org/wiki/Multiple_personality_disorder
While the operation of the normal personality might share attributes with MPD, the differences between them are so numerous and important that I think it is a mistake to equate the two.
It's great that you notice that the human personality is dynamic and can be seen as a play of forces and that these forces can be negotiated with and utilized for rapport and influence. I've done so myself, so has anyone (intuitively, at least) who has used persuasion with an ambivalent person. But that does not mean that everyone has MPD, and it certainly doesn't mean that everyone is schizophrenic.
It's kinda like saying that everyone, to an extent, has chicken pox, because it can be argued that the average person shares a number of traits, arguably, with someone with chicken pox.
