**OFFICIAL** LOST Season 3 Episode 6 Thread -spoiler free-

[dangerous_badman]

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He might have figured, or guessed, that Juliet is lying / making a move for the leadership, and is hoping that threatening to kill Ben might force acquiescence from the rest of them, but he surely can't be certain that every Other is 100% loyal to Ben.

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He can be pretty sure that a majority of the others currently surrounding ben/juliette want ben alive, otherwise they could all just kick ben's ass together. But juliette told jack that if he killed ben, they could easily pass it off as an accident. That gives jack reason to believe his plan would work.

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I appreciate Ben has the majority, this much is apparent. The problem is that an unknown number of Others may not be loyal to Ben, ie. the guy Jack radios and instructs to release Kate and Sawyer may be loyal to Juliet and just refuse, allowing Ben to die. Any Others that might be told to give them free passage out of the Others' compound might just elect to shoot them and force Jack to make good on his threat.

The point I'm making is that a plan that involves "do XYZ or I will kill Ben" is kinda shaky when an unknown proportion of the Others may have a vested interest in provoking Jack to do it.