Once we renounce the retributive dimension of punishment we have lost the only justification for punishing someone.
We do not punish innocent people to deter others; we punish only the guilty and that is because they deserve it.
Punishment may be considered in two ways. First, under the aspect of punishment, and in this way punishment is not due save for sin, because by means of punishment the equality of justice is restored (Aquinas)
We have lost the understanding that sin deserves punishment, demands punishment, and it is necessary because nothing else restores “
the equality of justice.” We cannot ignore the church’s understanding of retribution because we have grown uncomfortable with the idea ourselves because without that understanding there is no just basis for any kind of punishment.
“A penalty is the reaction required by law and justice in response to a fault: penalty and fault are action and reaction. Order violated by a culpable act demands the reintegration and re-establishment of the disturbed equilibrium …"
*For the fundamental demand of justice, whose role in morality is to maintain the existing equilibrium, when it is just, and to restore the balance when upset. It demands that by punishment the person responsible be forcibly brought to order; and the fulfillment of this demand proclaims the absolute supremacy of good over evil; right triumphs sovereignly over wrong. *(Pius XII)
There is a recent article in First Things titled Just War as Punishment that gives a good explanation of the value of and need for retributive punishment. The concepts are no different with respect to individuals.
firstthings.com/onthesquare/2013/10/just-war-as-punishment
Ender