For the necessity of not punishing the innocent is not moral but logical. It is not, as some retributivists think, that we may not punish the innocent and ought only to punish the guilty, but that we cannot punish the innocent and must only punish the guilty.... The infliction of suffering on a person is only properly described as punishment if that person is guilty. The retributivist thesis, therefore, is not a moral doctrine, but an account of the meaning of the word "punishment" (p. 10).
Quinton argues that to say, I am going to punish you for something you have not done, is linguistically absurd and illogical. I agree. Certainly one can inflict pain and suffering on an innocent person or incarcerate an innocent person or even execute an innocent person but it is never correct to call those punishments. Punishment only makes sense if it is served on a guilty person.
The word punish is defined by Merriam-Webster as:
1 a : to impose a penalty on for a fault, offense, or violation b : to inflict a penalty for the commission of (an offense) in retribution or retaliation
2 a : to deal with roughly or harshly b : to inflict injury on : HURT
It is apparent that only meaning #1 has reference to punishment in a technically judicial sense. Meaning #2 is the non-technical, non-judicial meaning of the term.
The word penal is defined by Merriam-Webster as:
1 : of, relating to, or involving punishment, penalties, or punitive institutions
2 : liable to punishment a penal offense
3 : used as a place of confinement and punishment a penal colony>
Both penal and punish are derived from the same Latin root poena.
Therefore, the whole concept of the Penal Substitutionary Death of Christ is illogical. If Christ was innocent, then he could not be punished in the judicial sense of the term. The suffering that was inflicted upon him is not properly called punishment. Penal Substitution, I conclude is an oxymoron.