Dogen, Richard and the magic dagger by Terramatrix119

This is my theory why Dogen asked Sayid to kill MiB with the silver dagger.

I think Dogen believed Sayid could kill the Man In Black with the dagger, although I think he also hoped that if he was unsuccessful then MIB would kill Sayid for him. Win-win for Dogen! Or so he thought, as actually neither scenario happened. But the reason why he thought it would work was down to Richard.

As we see in Ab Aeterno, MiB gives Richard this dagger, tells him to kill "the devil" and to NOT let him speak. Richard though gets beaten by Jacob and the knife is taken off him. Richard is then given the job of Intermediary - to talk to and advise new arrivals to the island. This would include Dogen in the future. Richard and Dogen clearly must have met on at least once, much more likely many, occasions. As the new leader of the temple, I believe Jacob, through Richard, would have informed Dogen of the Man In Black.

Now in the episode Sundown the dagger is buried in a flowerpot in Dogen's room. Why? Well I think the obvious answer is that Jacob does not want MiB to get his hands on that dagger, and if Jacob is traveling off island to find candidates then the dagger needs to be where MiB can't get - the Temple. So Jacob gives Richard the dagger to put in the Temple, and as we see Dogen likes his plants so it is hidden and buried (like many Island objects) in a pot.

I would imagine that Richard told Dogen a story along the lines of "I was told to kill the devil with this dagger, but I let him speak and I couldn't". From this Dogen could easily extrapolate the wrong conclusion, or perhaps he was told the full story and chose to believe the dagger could also kill MiB. So when he sent Sayid off with the dagger, he tells him the information Richard was told. Also he probably thought that as Jacob is dead it doesn't matter if MiB gets it back, which is why he never used it before.

So there we go! Don't know if we will see this but I'd like to see some Dogen/Richard scenes so fingers crossed!

Cheers :)