A major mythology of the show is in regards to the Manichean allegory – black vs. white, good vs. bad. Is someone destined to be good? Is it a feature you have or you don’t and is it something that can coexist inside of you? Is goodness and badness something with which the individual is constantly struggling with or is it decided upon at an early age? Finally, what does it mean to be good or bad? The characters are all constantly struggling with that. Something that’s come up on the recent episode, Ab Aeterno, is more of the relationship between the Man in Black and Jacob. A few more details have been given, yet it’s still difficult to determine which is the bad guy, and which is the good guy. But I think that’s the entire point.
Jacob declares to Richard in this episode that he brings people to the island to give them the opportunity to be good. But they seem to be failing as he also said that all the people he’s brought up until that point were dead. The nature of good versus evil is yet again brought to the forefront. What is also interesting about these two characters is that no one seems to be able to see them unless specifically invited to do so. Jacob declares that no one is allowed into his cave unless invited, and other than Richard, no one knows what the “original” form of MIB looks like (“original” is in quotes because we cannot even be sure that this form we see isn’t the inhabited body of another, similar to the way he took over Locke’s body). This observation has lead me to, what I think, is an interesting theory.
So much of the show deals with not only human nature but how people deal with their own nature. The survivors of oceanic flight 815 were all struggling with something that was essentially self-inflicted. “They're all carrying around a shitload of guilt—for various reasons—and no matter how much they repent to others, they'll never truly be free until they forgive themselves. They're the causes of their own suffering, and their guilt is their cross to bear (http://jezebel.com/5501254/lost-recap-la-vida-loca-de-guyliner).” They’ve all struggled with their desires to be good or bad -- Sawyer had his demons over tracking down and killing the man who he thought was the cause of his parents’ deaths (even though he turned out to be wrong). Kate was running from the law after killing her stepfather, an issue itself that was not clearly good or bad. Jack was dealing with the death of his own father and feeling that it was his fault and blaming his own inadequacy for his father’s death. The list goes on and on, but ultimately all the survivors are dealing with something very personal and they are all fighting their own demons both internal and external.
That being said, since no one seems to be able to see MIB and/or Jacob, AND since we never get a name for MIB, my theory is that they are one in the same. They represent the two sides of the same person. MIB IS Jacob. One is Id and one is Superego: the id (possibly MIB) tries to lead people down the paths of their own desires and follow their impulses while the superego (presumably Jacob) tries to guide people to do good and believes that goodness is attainable. The island acts as the ego, the mediating force between these two impulses that brings them together and allows people’s two opposing sides to be mediated. Everyone has “good” and “bad” impulses in them, and life is all about how one control’s those desires. Similarly, these two forces on the island are trying to sway people one way or another and it will ultimately be up to them to decide how they want to behave and who they want to become.
The island is the perfect place for all these people to put their struggles to the test. They can face their insecurities and their shortcomings and put them to the test. Jack, the ultimate control freak and perfectionist has to learn that he cannot infact control everything. Sawyer, the consummate conman and loner must learn to live with people, and not only does he do that but he also becomes the head of Dharma security at one point. Even Sayid comes to terms with his violent and abusive past and sees proverbial light and regrets his former ways. Claire, a confused teenager who wanted nothing to do with the life growing inside her had a chance to become the mother she thought she didn’t want to be. The island acts as the mediating ego and creates a space where people can have a second chance to make good on what was a once failing and flailing life. Furthermore, all these people who were once pretty much loners (not just Sawyer) have come together and have found a place where they all belong and have a role of sorts to learn to live as a community, whatever that might mean.