The question of Morality and

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…defending yourself from a life threatening attack you are being courageous, which is considered a virtue. Secondly you are saving a life, which is both shows piety (remember showing life should be revered) and justice (it is wrong to kill). With these three virtues behind our initial maxim, it seems that self-defense indeed is justifiable, and in fact by doing so you are demonstrating the same virtues that are inherently shown in the maxim itself.