The most deeply held beliefs cannot be changed by argument. They live in an inward and secret place, a dark sanctuary where the desires and fears, prejudices and reasonings of a lifetime stand like silent totems.

And no beliefs are more deeply held than those concerning vengeance for the taking of human life. From the implacable Biblical injunction "an eye for an eye" to Camus' impassioned plea that men be "neither victims nor executioners," from the tragedies of Aeschylus to the nightmare of unleashed revenge in Jacobean drama, from the self-crucifying moral dialectic of Dostoevsky to the hunt 'em down and kill 'em ethos of a thousand Hollywood films, blood atonement has haunted the human imagination.

The ultimate retribution obsesses us because it exists beyond the small circle of light cast by everyday morality. There are no signposts in this realm -- or, if there are, they cancel each other out. "An eye for an eye"? "Vengeance is mine, saith the Lord."

The instinct to kill the killer of one's child is as clean as the lion's instinct to hunt -- yet if we live under the rules of civilization on Monday, shall we suspend those rules when the unthinkable happens on Tuesday? We are taught that human life is sacred: under what conditions, if any, should it cease to be regarded as such? What place does the jungle have in our moral mathematics?

Two new films, Tim Robbins' "Dead Man Walking" and John Schlesinger's "An Eye for an Eye," explore this issue from different directions. Neither film will probably change the minds of those who are certain that they possess the truth. What they reveal -- one through its artistic success, one through its failure -- is that such moral certainty does not, and should not, come easily. In these days in which every two-bit politician sets himself up as an apostle of virtue, this is a useful lesson.

John Schlesinger's "An Eye for an Eye" is too slight and flawed a film to bear much discussion. Trying to make hay off the O.J. Simpson debacle, it offers a stale variant on the venerable what-to-do-when-the-law-fails plot. The twist here is that the aggrieved party (her daughter's killer gets off on a ludicrous technicality involving, of course, DNA testing) is a yuppie housewife. Even this formulaic story line could have been potentially interesting, but Schlesinger makes things much too easy for himself. By presenting the killer as a monster whose extinction is obviously justified (after being freed, he kills again and threatens the mother's surviving daughter), the director avoids having to deal with more profound issues -- pathological obsession, the moral questions of taking the law into one's own hands. Schlesinger's vision is about as deep as a New York Daily News headline: his wish-fulfilling tale appeals to our shallowest O.J.-irritated emotions, and so says nothing.

Next page: The power of uncertainty