2. It is not unlawful to do something which will cause one's own death provided that the action has some other immediate and good effect of great importance, which counterbalances the loss of human life, and this is not intended. This is merely an application of the principle of a double effect which was explained in the Book on Human Acts. The captain of a man-of-war, for example, which in time of war is in danger of falling into the hands of the enemy, might blow up the ship in order to prevent so great a disaster befalling his country, although the act would cause his own death and that of others in the ship. He does not intend the destruction of human life; the immediate effect of his action is to prevent the ship falling into the enemy's hands. The public advantage counterbalances the loss.
3. Similarly, for good reason I may undertake dangerous work, go to unhealthy climates, or lead a kind of life which will lessen the number of years that I shall live. Somebody must do such things; they are useful to the community or to myself, and I do not intend the shortening of my life. It would be wrong to expose my life to probable danger merely for the sake of getting money or notoriety; such reasons do not justify us in seriously risking human life.
4. As we have not the ownership of life, so neither are we the owners of our limbs so as to be able to dispose of them at will. A man is not justified in mutilating himself in order to avoid military conscription, or to excite commiseration, or to gain money. The amputation of a limb is permissible when such an operation is necessary in order to preserve life; for we may sacrifice a part for the safety of the whole.
5. We are obliged to take ordinary means to preserve our lives, for to do otherwise would be virtually to commit suicide. There is no obligation to take extraordinary, unusual, or very painful or expensive means to preserve our lives. And so one in feeble health, who will probably die if he spends the winter in England, is not bound to expatriate himself and go and live in a milder climate. Nor am I bound to undergo a painful and costly operation in order to save my life; I may if I like choose rather to die, unless my life is of great importance for the common good, for then the public good must be considered first. Except in such a case as this, a superior could not oblige a subject to undergo a very painful operation or to submit to the amputation of a leg; obedience to human authority does not seem to extend to such matters as these.
