Is Our Shadow Function Evil?
In jungian terms, your dominant preference is your hero function: your secondary preference is your good parent, and your third preference is your inner child. Lastly, the fourth function is the "shadow". However, lots of jungian theories suggest the fourth and third function is already highly involved and important in your psyche - all four functions are more or less conscious. So is the fourth function evil? Is the third function "childish" like the Freudian Id?
The argument by Jung is that our shadow is more influenced by our unconscious desires - desires we have, but do not fully acknowledge. Because we are less conscious of our fourth function, we can exhibit most of our "bad" behavior in the fourth function and still remain unaware of that we are doing these things - that we are hurting others, without realizing it. This is one of the stronger arguments - yes - most bad behavior is "involuntary" or "unconscious" - very few are evil with evil intentions. Even psychopaths build themselves up to be important to society - they say their role in society is to teach us about how harsh the world is, to force us to adapt and prepare ourselves for the worst in other people. That is an important worldview for an "evil" person - all humans seek to justify and rationalize their own behavior, or to pretend it isn't there.
In groups, it's hard to distinguish between a persons four cognitive functions - the maths are so complex and things happen so quickly most people use all four of their functions simultaneously. They laugh, and chat, and move, and dance, and listen, and switch between all functions with great speed, using them all in tandem. An INFJ in a group loses much of his introverted self, and becomes more of a hedonistic explorer, perhaps that's why INFJs avoid large groups so often? Because they prefer to have the focus of just one or two functions at a time? Perhaps extroverts have a more balanced use of all four of their functions?
Atleast, something I've found to be true is that the fourth function is more evil when we are children or teenagers, and it's role in our psyche diminishes when we become older. Around their 30s or 40s, most people have struck some kind of peace with their fourth function. They've had their midlife crisis and they've finally integrated all their four conscious functions and found some way to balance it all. For most people balancing the fourth function is necessary for victory - for self-realization. And I believe that the hero function - while it may never be evil, it can be sometimes misguided, it can project negative personality traits on good people, it can assume and falsely believe something to be true that isn't. This may or may not be the cause of the fourth function - at least, without the fourth function, we wouldn't be heroes at all, we'd lack our primary challenger, our primary driver of growth.
Another common trope is that - the greater the light - the greater the shadow. My interpretation of great here is not how much your prefer your first function, or how much you love it, but how strong it is: an introverted intuitive with an amazing intellect will often have a greater fourth function as well. An intelligent person will have to watch out more for their fourth function as well. It's easy to lose track of everything you say and do, hard to be conscious and aware of it all, some things just happen on autopilot. Somethings we think and take in without realizing it. And our fourth function can play elaborate games and pranks on our mind to awaken us or trigger growth in us. Well, the fourth function is us after all, it's a part of who we are. A part of what we need to be happy, a key to growth, a necessary evil.