ABOUT THE ONLY THING the public learns from the on-again, execution of John Louis Evans III in Alabama is how electric-chair design has advanced over the years. No more the drab, brown, wire-wrapped job we'd grown accustomed to in the death-row moview of the 1930s, the chair that will serve as the next to the last resting place for Mr. Evans is a bright, "designer" yellow; and from the pictures we've seen, it looks to be plastic, with rounded edges-the way they make kitchen furniture safe for children. Granted a brief stay of execution at the 11th hour by Supreme Court Justice. William Rehnquist, Mr. Evans did not die in that chair last Friday, as scheduled. And yesterday, for nuclear reasons, he decided to challenge the constitutionality of the death penalty. Yet from the start he has maintained that he wants to die. Having confessed to the 1977 robbery-murder of a Mobile pqwn-shop owner, he told the court that he wanted the death sentence, and that if released he would do it all again. The judge and jury obliged, and later the Alabama Supreme Court turned down an appeal from Mr. Evan's lawyers-an appeal Mr. Evans opposed.

On the surface, there is a kind of clean logic to this story. A remorseless murderer prefers execution to life in prison; a punishing and self-protective society seeks to get rid of him; the minds meet. It has the same clean logic of Mr. Evans' own statement that he was "ecstatic" about the prospect of dying because "it means getting my freedom." That is to say that none of this really makes sense at all-at lease not from the viewpoint of a public about to witness a sanctioned killing that is supposed to make society safer criminals wary, and to affirm the standards of civilization.

For one thing, the safety of society is not in question, since society would be equally safe if Mr. Evans were to be given a life sentence without chance of parole. As for whether or not would-be murderers will be more reluctant to pull triggers as a result of the execution, that is an imponderable. One thing is certain: Mr. Evans has done nothing to diminish the swaggering image of the hardened criminal by taking his stand. Without a gulp or a hitch he told the jury he wanted to die; and until recently he only spoke of regret in terms of his own career, never mentioning, or apparently caring about, the life he took. For those inclined to be impressed by such an attitude, his choice of death over the absence of liberty in fact be read as model killer behavior.

That leaves the matter of the standards of civilization, which are, to say the least, confused on such issues. On the one hand, the state condemns the taking of a life as the most serious, the most anti-social of crimes. On the other, it takes a life in return, to make its point. In 1976, the U.S. Supreme Court held that "the punishment of death does not necessarily violate the Constitution." But if one regards the Constitution as the conscience of the republic, how can that conscience not be violated in the most fundamental way by the spectacle of approved murder?

Mr. Evans has sought to die. That, oddly, is his privilege. It is also our privilege not to grant him his, especially when by so doing we condone a savage ritual, the aftermath of which is-as it always must be-a feeling of vast national emptiness. Most likely Mr. Evans will soon be beyond your reach, as was Gary Gilmore before him, and Caryl Chessman before him, along with thousands of others going back from ours to the darkest ages. But in the future it would be gratifying to measure our progress in this area by something other than a bright yellow chair.