Some people argue the these issue can be resolved by making use of the ethical princibles already addressed in earlier chapters. The principles of beneficence and nonmaleficence, of doing good and avoiding evil, provide ready arguments to support those who wish to defend merciful killing as well as decisions to withhold or withdraw treatment. In the case of patients who are competent and capable of making their own choices, the principle of autonamy also provides as moral basis for approving of or at least tolerating treatment- refusal decision by patients. It also help explain our great reluctance to approve of killing a person who does not want to be killed, even if we have good reason to believe that the person would be better off dead.