Capital Punishment


What would be the Thomistic view on capital punishment?


According to Aquinas:

Therefore if a man be dangerous and infectious to the community, on account of some sin, it is praiseworthy and advantageous that he be killed in order to safeguard the common good . . . . ST IIa-IIae, q. 64, a. 2.

It is permissible to kill a criminal if this is necessary for the welfare of the whole community. However, this right belongs only to the one entrusted with the care of the whole community — just as a doctor may cut off an infected limb, since he has been entrusted with the care of the health of the whole body. ST IIa-IIae, q. 64, a. 3.

(See also his treatment of capital punishment in the Summa contra Gentiles III, c. 146 which is essentially the same (though less nuanced).)

Thus, according to Aquinas, the state which is entrusted with caring for the welfare of a society (not private citizens) may put a criminal to death when it is necessary to protect the rest of society. The question for Thomists, and for all citizens in a democracy, is when, if ever, this is necessary. It is hard to answer on Thomistic grounds. Aquinas does believe that it may be necessary to kill heretics since they threaten the faith of believers, but he is not very definitive, even on what is for him the worst case scenario. (See the essay, Tolerance.) I, personally, do not think it is ever NECESSARY to take someone from prison and kill them, but I realize it may be a tricky question.


Hello, I am to give three arguments that support St. Aquinas’s position on the death penalty. So far from what I am understanding, St. Aquinas was for the death penalty, but he sort of confuses me because at the same time he sounds like he is against it. Can you please help me? 


I think Aquinas really only gives one reason in ST II-II, q 64, aa. 2-3 for why a sinner or evil-doer (criminal) may be executed, and that is to protect the rest of society.  Most of his arguments are meant to overcome obstacles: killing sinners may harm the good (a. 2, obj. 1), sinners should be spared to allow their repentance, killing a man is always evil (a. 2, obj. 2), and one may not use an evil means for a good end (a. 2, obj. 3).  His answers all stem from the basic principle that the good of society is the goal of government, and threats to that good should be eliminated when necessary so that if killing criminals does more harm than good (reply 1) or can be delayed to allow repentance (reply 2), criminals should not be killed.  The third obstacle seems the hardest, so he tries to show that the death penalty is not using an evil means for a good end, but that criminals have become sub-human by their criminal activity which threatens society, so their deaths is ordered to the good of society as animals are used for food (a. 1).  Being a part of the whole of a society, a criminal is like a diseased limb which can be cut off for the sake of the health of the whole body when necessary.  Criminals by being criminals set themselves apart from the goal or purpose of the rest of society, and so their preservation is not part of that goal (as the preservation of law-abiding citizens is part of the goal).  Being outside the protection of the rest of society, the death of criminals may serve to further the good/goal of the rest = the common good.


Thank you- can you please explain this? “His answers all stem from the basic principle that the good of society is the goal of government, and threats to that good should be eliminated when necessary so that if killing criminals does more harm than good or can be delayed to allow repentance (reply 2), criminals should not be killed.” The underlined portion confuses me. Do you mean killing criminals does more good than harm?


Killing criminals may do more harm than good, or may just involve committing some unacceptable harm.  As he says: “This occurs when the wicked cannot be slain without the good being killed with them, either because the wicked lie hidden among the good, or because they have many followers, so that they cannot be killed without danger to the good . . .”  So the government should not kill criminals if this will (or merely might) cause the deaths of innocents.  Thus, police are generally careful not to storm a place where there are hostages.  Even if there are 10 terrorists, and 2 hostages, for the police to kill all 12 would be unjustified even though more terrorists than hostages were killed.  Killing any hostages is unacceptably bad, no matter what amount of good is achieved by killing terrorists. But I think it might also make sense for the government not to execute a terrorist/cult leader since he would be viewed as a martyr in the eyes of his followers, and this might embolden them to further violence.  But it would depend on the cases. 

This is the rationale for some people who oppose the death penalty in the US today: Statistics show that states with the death penalty actually have higher murder rates.  The reason for this, it is argued, is that state sanctioned killing causes people generally to place a lower value on human life, and to believe that killing people is an acceptable way to solve problems.  Since using the death penalty has a bad affect on the views of the general public about the value of life and death, it should not be used, even if it might be theoretically justified.

Aquinas thinks that the state may kill criminals when necessary to protect the common good, but that means it should be used only when that is the only way to protect society and only when one does not cause other or worse harm to society by killing them.

Revised 12/18/2022

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