Melanie Klein, the originator of object relations theory, described early childhood relationships in terms of "splitting." (Bear in mind that what follows is a gross oversimplification.)
In the Kleinian model, very young children are unable to differentiate between the nature of an "object" (a person, animal or even thing that has been "cathected," or invested with emotional significance) and its relationship with/effect on the self. The child initially experiences the nursing mother as only a breast, since that is the part that is most significant to the child.
At this stage of development, children think in all-or-none terms; they can't accommodate ambiguity or inconsistency. So when they are being fed, the breast is good, and when they are hungry, the breast is bad and withholding. The two are experienced as different objects, the good breast and the bad breast. This primitive inability to integrate such images is thought to be responsible for the preponderance of evil stepmothers in fairy tales, among other phenomena.
Eventually, most children move out of this stage (called the "paranoid-schizoid position") into what Klein termed the "depressive position," the understanding that we all contain elements of good and evil, and that each person is on her or his own trajectory, not necessarily revolving around us.
But outgrowing a stage doesn't mean relinquishing everything connected with it. Most of us exhibit artifacts of infantile thinking and behavior on some level.
For example, I know that my knee-jerk reaction to a shock or surprise tends to be all-or-none. My first impulse in an argument is to trash the entire relationship; when a hero lets me down suddenly I can easily flip him into a villain. In sophisticated psychological jargon, I want to throw the baby out with the bathwater.
I have learned to temper this reaction over the years, because it really is just a relic of early splitting that is activated under stress. After a few deep breaths, I am able to address the complexity of the situation at hand and attempt to understand why someone else may have acted in a way I didn't like or wouldn't have done myself.
I think that many adults carry remnants of the paranoid-schizoid position, manifested either in the type of flipping I am tempted to engage in, or in a related inability to see any good in people whose actions or positions they dislike, or to see any faults in those they admire (leading to their making enemies of those who point out those faults).
I think it is important to recognize how easy and natural it is to fall into this sort of thinking, and how difficult, but critical, it is to move beyond it. We need to be able to think critically about those we admire and love. A person can be a great, visionary political leader and, at the same time, a raging misogynist in his personal life. A child can be a smart, loving and vulnerable daughter and sister, and still be a bully at school. And a coach can be heroically dedicated to his students, to his team, and to his institution and still turn an unconscionable blind eye to horrific abuse. If we can't recognize the capacity to harm in those we admire, the harm will continue unchecked--and that serves no one, including the idol we are contorting ourselves to protect.