When 53 percent of California voters rejected Proposition 34 on Election Day, they were choosing to retain the death penalty instead of replacing it with life in prison without the possibility of parole. The same day, a larger percentage of the California electorate voted to radically reduce the number of felons serving life sentences under the state’s so-called “three-strikes” law. In both cases, the punishment costs the state dearly—either because of years of fighting an inmate’s appeals or years of housing and feeding him. How could the same voters care so much about saving money in one context but be so indifferent to the squandering of it in another?

The answer to that is something that the backers of Prop 34 didn’t seem to understand—but if they did, then it’s all the better that the measure failed. When Americans think about ordinary matters of crime and punishment, economics are key. But when you throw the death penalty into the mix, moral considerations rule. Economic arguments matter at the margins, but at its core, the debate over the death penalty is never really about dollars and cents—rather, it turns on our id⁄ea of what it means to be a human being.

I doubt the 726 inmates on California’s death row care very much about this debate. The state has not executed anyone since January 2006, when officials administered a lethal injection to 76-year-old Clarence Allen, and because of a federally imposed moratorium there is no immediate prospect that any of the dozen or so death-row inmates whose appeals have run their course will be put to death any time soon. In fact, California has executed a total of only 13 people since capital punishment was reinstated there in 1978—an average of one execution every two and a half years.

Meanwhile, in Texas two days after the election, Mario Swain became the 13th person executed in the state this year. Swain was my client. Ten years ago he broke into a house owned by a woman named Lola Nixon, intending to commit burglary. While he was inside, Ms. Nixon returned home, and Swain killed her.

The courts ruled against our final appeals late on the night of Nov. 7, around 26 hours before Swain was put to death. I decided to wait until Thursday morning to tell him, hoping that by keeping the news to myself, it would give him a better final night. Another lawyer might have told him right away. Death-penalty lawyers disagree about such things.

And Prop 34 failed in part because death-penalty opponents also disagree about the wisdom of trading your moral foundation for a fiscal argument.

Support for Proposition 34 came from an odd coalition of civil libertarians, death- penalty opponents, prosecutors, prison officials, and fiscal hawks. They argued that the death penalty accomplishes no purpose that imprisonment could not accomplish just as well, yet it costs substantially more. That argument is incontestably true, and the fact that the argument persuaded slightly more than 47 percent of voters is significant, considering that when capital punishment returned to the state, it was backed by more than 70 percent of the voters.

But while support for ending the death penalty was cold and actuarial, opposition to the measure was emotional and raw. Perhaps the most passionate opponents were those who have lost loved ones to murder. Joining them were law-and-order advocates who perpetuate the false notion that your typical death row inmate is an incorrigible, remorseless, psychopathic killing machine who has absolutely zero chance of living a productive life.

As death penalty lawyers know, most residents of death row—including, until the night of Nov. 8, Mario Swain—do not fit the Hannibal Lecter caricature. Most murderers are in fact remorseful, and many are capable of growth and change.

Which brings us to the final demographic group who opposed Prop 34: those death-penalty opponents who understood that by supporting life without parole as an acceptable alternative, the measure’s backers were legitimizing the same mistaken belief about murderers that fuels death-penalty fervor, and were therefore surrendering the moral basis of abolitionism. In other words, you can’t tell a death-penalty supporter she’s wrong to think all murderers are beyond redemption, and then turn around and say it’s OK to keep them all in prison forever, just because it’s cheaper.

Unlike the debate over three-strikes laws, to death-penalty supporters the core issue is desert: If you kill someone, you forfeit your life to live among us. For abolitionists, it is about the possibility that even people who do something horrible can change. Some murderers do need to stay in prison for the rest of their lives. Many of them don’t.

I don’t know which group Mario Swain was in. During the eight years he resided on death row, he spent 23 hours a day alone in a 60-square-foot cell. Nobody was interested in giving him access to education or socialization, or teaching him technical skills. When I said goodbye to him yesterday, I told him I wished I could have accomplished more, and that that I was sorry our society had given up on him.

Those who would replace executions with life without parole give up on murderers in exactly the same way. Abolitionists have something here to learn from the Prop 34 opponents whose itch for vengeance roars so hot that they’ll break the bank to scratch it. Where the death penalty is concerned, moral foundations matter, and you don’t show you respect for human dignity by being willing to lock up every last murderer and throw away the key.