Here's a LOST theory for you: If Jack and Claire don't have their recommended dosage of alcohol PEOPLE DIE! There is a lot of pent up anger going on, and island rehab doesn't seem to be working.
Jack Shephard's father (Christian) was an alcoholic, and maybe that's an unhealthy lifestyle. Was it a trait responsible for the man's death? Possibly, if he's even dead. Either way scotch was always there to calm him down. Conversely, sober Jack's been on edge a lot as of late. He may not have the facial hair anymore, but off-island beardo Jack was drinking heavy, and as a result caught up on a lot of Nirvana albums he always promised himself he'd buy. Now? Now Jack has came back to the island for the same reason Charlie Sheen is considering a stint in rehab:
While Jack's return to the Island might have inspired him to start beard trimming again, without booze the man's a ticking time bomb. Look what he does to the newly discovered magic lighthouse mirror:
Oh, and his half-sister keeps breaking $hit too, like this poor guy:
The rage! My God Carlton, get these kids some Seagram's Seven stat! We know, in our reality, a surefire way to be kicked off the island is driving around Hawaii with too much booze in your system... but if Jack's really a candidate he'd better hope Flocke is hiding some Johnny Walker somewhere close by.