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One argument for retribution theory is "moral proportionality." "Moral proportionality" means that a punishment's severity depends on the degree of moral offense that the perpetrator created. We all believe retribution is the right thing because wrongdoing merits punishment. Three components of an offense are (1) the magnitude of harm. (2) the perpetrator's intentions, (3) extenuating circumstances that exacerbate the immorality of the perpetrator's action.
One argument for incapacitation theory is that the cause of the wrongdoing lies primarily within the perpetrator. The argument is that it is morally right to incapacitate someone who has done bad things in the past.