Rose could have given him her lifejacket

The argument

A simple solution that the film overlooks, proponents argue, is that Rose was wearing a life jacket the whole time — and that life jacket could have been used to save Jack rather than letting him freeze in the water. The fatal factor in Jack's death was prolonged immersion in near-freezing water while Rose stayed dry on the floating panel. But the buoyancy of a life jacket is exactly what is needed to keep a body afloat, and proponents contend that Rose's vest, whether given to Jack or tied beneath the panel, could have changed the outcome. The argument runs in more than one direction. Most directly, Rose could have shared or surrendered the means of staying out of the water: a life jacket tied to the underside of the wooden panel would have increased its buoyancy enough to support both of them, as some have demonstrated, while Jack could have used the added flotation to stay above the lethal cold. Rose, already on the panel and partly out of the water, was in less immediate danger than Jack, and the unused buoyancy she carried represented a resource that was simply never deployed to keep him alive. From this standpoint, the tragedy was not forced by the physics of the situation but by a failure to use the equipment at hand. A life jacket is designed precisely to keep a person afloat in cold water, and one was available throughout. Whether given to Jack or used to make the panel hold them both, it offered a path to his survival that the scene ignores. Because Rose could have given him her life jacket, this argument holds, Jack did not have to die to save Rose.

Premises

Counter-arguments

Critics argue this misidentifies what killed Jack. A life jacket provides buoyancy, but Jack died of hypothermia from immersion in near-freezing water, and buoyancy does nothing to keep a body warm — floating in the same lethal cold, he would still have succumbed. Simply handing Rose's vest to Jack would have kept him afloat as he froze, not saved him; only getting his body clear of the water would have, and that returns to the disputed claim that the panel could hold two. Tying the jacket beneath the panel is the MythBusters solution, obtainable in a calm test but, critics say, not something two exhausted people in darkness and shock could have devised and carried out before the cold overcame them. On this view the unused life jacket was not a squandered means of survival but, given the temperature, largely beside the point.

Rejecting the premises

[Rejecting P1] Critics note Jack died of hypothermia, not drowning, so a life jacket — which prevents sinking but not freezing — would not by itself have kept him alive in the water. [Rejecting P3] Using the jacket to make the panel hold both returns to the disputed buoyancy claim, and doing so amid darkness, exhaustion and shock was likely beyond what the characters could achieve in time.