In the second half of Don Quixote, Sancho Panza becomes the governor of an island, and develops a reputation for being wise. One peculiar institution of the island is that whenever somebody sets foot upon it, he is asked where he is going, and what for. If he happens to be lying, he is hanged. One exceedingly clever man comes to the island, and is asked the usual question, to which he answers that he is going to the gallows to be hanged. Anyone with a rudimentary knowledge of logic will recognize this as an irresolvable antinomy (a paradox only seems to be unsolvable on the surface). The hangmen go to Sancho to ask what is to be done with this man, and he thinks over it for a while, and recognizing its irresolvability, answers that his former master once told him that it is, in any case, better to be merciful than severe, and the man avoids being hanged at the gallows.
It would be perhaps comical if it didn't involve life and death, but there are certain conservative commentators who are opposed on principle to former Governor Ryan's blanket clemency for all death row inmates. They argue that, while the judicial process may be capricious and arbitrary in certain cases, the blanket clemency is equally arbitrary and capricious. They argue that the decisions of one man (especially one whose victorious campaign for governor included support for the death penalty) should not be allowed to overrule the collective decisions of numerous judges and juries.
Arbitrary and capricious...really? Let's dismiss caprice off the bat. Capricious decisions are not characterized by a long, complicated period of study, a long period of consideration, or a letter signed by numerous law professors. Caprice is instead unaccountable and by whim. Juries, given similar cases, incline toward giving a black suspect death, and a white suspect life without parole. Public defenders are at best overworked, and at worst asleep during the trial. That is unaccountable. That would be whimsical except that nobody's whimsy can be held to account. It is systemic.
Arbitrary is a little more complicated. A government where one man is given the arbitrary decision of life or death is known generally known not as democracy, but a tyranny. But wait a moment. Let's consider for a moment that every death row inmate, after all legal appeals are exhausted, still has recourse to ask for clemency from the governor. (This is at least the case in Illinois. In the nation's most death-penalty obsessed state, Texas, the governor has no power to grant clemency unless a panel first refers the case to him.) What new information could possibly come to light here, at this juncture? Surely a governor has more pressing duties than to go over every scrap of evidence in the trials and appeals. The decision cannot be but arbitrary. Imagine having to do this with every single case that runs out of appeals. Whatever the facts were before, it is only your word that decides whether the particular inmate lives or dies. That would be one singularly onerous and repugnant duty.
Consistency, as opposed to arbitrariness, requires that every single case be handled the same way. Given what we know about the inequities of the criminal justice system, every single case death penalty conviction is either plainly wrong (these are usually rooted out by appeal, but Ryan released four prisoners altogether for this reason) or else are irresolvable, if not in theory, at least in practice (evidence being lost after the trial, evidence never having been collected, police interest in protecting their own, a whole host of reasons). There again is the Sancho Panza principle mentioned above. Given a case where no decision can be made, it is better to be merciful.