Two of the most useful concepts Carl Jung created were called the Persona and the Shadow.
Essentially the Persona is your "ideal self," the one you like to think you are (and the one you want people to think you are), and then there's the Shadow, the part of you that you don't want to admit, so you project it on to others. Of course, this mechanism varies in degree from person to person. Those who are aware of it, and have a lot of self-knowledge, are less liable to engage in this defense mechanism -- and defense mechanism is exactly what it is.
Then there are those who are completely unaware of the Shadow. About them, Jung commented that when they were in the grips of that archetype, "You don’t have it, it has you."
I generally write about the Persona (which means "mask") and the Shadow in the context of scapegoating, i.e., projecting the rejected aspects of yourself onto others, and then attempting to ostracize or kill that person or persons, in an attempt to annihilate the rejected aspects. This is why M. Scott Peck quite correctly called scapegoating "the genesis of human evil."
It is based on projection, which occurs whenever ignorance of some aspect of our own psyche causes us to see certain other people as if they have that characteristic, when in fact they do not. The natural human response in such situations is to blame the person who seems to be "causing" the problem.
This projections is also, unfortunately, something that is done, for want of a better word, "unconsciously."
The novel I generally use to illustrate this process is Ayn Rand's Atlas Shrugged. Her heroes (which are her Persona -- her ideal self -- projected into fiction) are close to perfect. All her bad qualities she didn't want to admit to herself-- specifically envy -- she projected onto her "looters" and "parasites." Everyone in the novel is portrayed in the whitest of whites and the blackest of blacks -- either pure good or pure evil, either grandiose or devalued, either pure Persona or pure Shadow.
Some people think it's the greatest novel they've ever read, and others think it's the worst. Why such difference? It's because those who think it's great can see only the Persona but not the Shadow. Those who hate it see only the Shadow but not the Persona. Unfortunately for those who think it's a great novel, those who clearly see what the novel is about know it's mostly Shadow hiding underneath a very thin and very fragile Persona. That's why the ideas in it would never work in real life.
The concept of Persona and Shadow applies to modern politics, too. I've met people who cannot believe that Bill Clinton is a serial rapist and possibly a psychopath. I had one woman tell me all the women who claimed he raped them were lying. She could, like Clinton's other supporters, only see his charming, "I feel your pain" Persona and not his Shadow.
Those who despised Clinton could see his Shadow and knew his Persona was mostly a facade. Unfortunately, a lot of these people, at least the ones who supported Bush, could only see Bush's "patriotic" Persona but could not see his Shadow -- a man with substantial problems with his father, who never succeeded at any job he had, who avoided Vietnam by hiding in the National Guard, and who appears to be an emotionally unstable, untreated dry drunk.
Entire countries have a Persona and Shadow. "Patriots" can only see the good the U.S. has done, and refuse to see the bad. If they do see the bad, they deny it's bad and claim instead it is good, i.e., the fact the U.S. killed some 200,000 Filipinos in its invasion of the Philippines in the late 19th century. Then there is the bombing of the undefended city of Dresden, whose victims were 90% women and children.
Of course, there are those who can only see the U.S.'s Shadow and not its Persona. They can only see the bad it's done and not the good.
Entire religions have Personas and Shadows. The (false) Evangelical Christians who support the war see themselves as God's Chosen who have been selected to bring Jesus back by supporting Israel and war in the Middle East against Muslims. Such people can only see their Persona and project their Shadow onto Muslims. Not surprisingly, Muslims do the same thing -- which is why call the U.S. the "Great Satan" and ignore the horrendous slaughter than Islam has visited upon the world.
The entire art/science of propaganda is to convince the populace of their ideal Persona and to project the Shadow on the selected enemy. It's why the "enemy" is routinely -- indeed variably -- portrayed as subhuman, insane and evil, one who spits babies on bayonets. As Joseph Goebbels noticed, all the leaders have to do to lead the population to war is claim they are under attack and denounce protestors as traitors. In other words, convince the citizens they and their country are the good guys, and the enemy are the bad guys. Keep it simple, with the concepts of pure good and pure evil, and the masses of people will fall for it every time.
Those who are self-aware -- and have some humility -- understand they are not perfect. They know their good and bad qualities. They know their Shadow, and do not project it onto others. The more people understand and admit their Shadow, the less likely they are to project it onto others.
Unfortunately, it is extraordinarily difficult for entire countries to do this. Strictly speaking, masses of people (including entire countries) do not think but only feel. This is why the worst slaughter has always been group against group, especially when the vile concepts of "God and Country" are combined.
How can you recognize someone’s Shadow? One way is to notice that susceptible people will accuse other people of that which they lack. I’ve received many hatemails from the site, Free Republic. Invariably I was to them a coward for not supporting the current wars, yet in every instance none of them would fight in those wars themselves. They refused to admit they were cowards, and instead projected it on me.
Rush Limbaugh is a good example of the aforementioned projecting. Here is a man who did everything he could to avoid Vietnam, claiming he had a cyst at the bottom of his spine, and lying about hurting his knee in high-school football (his coach said he never injured it). Yet now he is rabidly for the wars, and disparages anyone against. Deep inside he must know he is a coward, but cannot admit it to himself, so he projects it onto others.
Jung's solution to the problem of the Shadow was to turn around and face it. This goes against our natural inclinations, for the Shadow, remember, represents all that we regard as evil or inappropriate, all that we have repressed in order to avoid the need to recognize who we really are. Our first tendency is to what to attack what we project.
Realizing and admitting both the truth of both Persona and Shadow, will, as the Biblical saying tells us, "set you free." Not from everything, of course, but from that particular curse.