This raises an interesting problem: why is it that it is morally permissible for me to jump out of the boat voluntarily to lighten it, but impermissible for you to throw me out? (Compare the notorious case of United States v. Holmes.) Lord Bacon claims that it is morally permissible for you to throw me overboard and he was cited (unsuccessfully) in the equally notorious case of R. v. Dudley and Stephens:
Necessity carrieth a privilege in itself. Necessity is of three sorts: necessity of conservation of life, necessity of obedience, and necessity of the act of God or of a stranger. First, of conservation of life. If a man steals viands to satisfy his present hunger, this is no felony nor larceny. So if divers be in danger of drowning by the casting away of some boat or barge, and one of them get to some plank, or on the boat's side, to keep himself above water, and another to save his life thrusts him from it, whereby he is drowned, this is neither se defendendo nor by misadventure, but justifiable.
It is alleged that Bacon justified himself by appealing to 'the canonists', but surely there is no support for this among them or the 'manualists'?
Another question: would it be permissible for me to ask you to help throw me overboard? Would it be permissible for you then to do so? I think so; it seems to me that consent makes a huge difference.
It might be thought that throwing me overboard is impermissible because it still involves intending an assault on my person, but would it, then, be permissible for you to remove a plank in order that I might fall overboard carried by my own weight? I think not. Perhaps the principle is that one shouldn't intend that somebody's body be moved without that person's permission? Still, it seems like a minor offence rather than the major one that we feel against Holmes and his fellow sailors.
Trolleys and fat people come in again here . . . .
Any thoughts, anybody else?