The main tenet of [Katherine Anne Porter's moral] philosophy is that the evildoers are not the most reprehensible people in the world, because they at least have the courage of their convictions. Nor are they the most dangerous people, since they can be easily recognized. The people who really need to be watched are the so-called innocents who stand by and allow others to perpetrate evil. Porter was to express repeatedly the opinion that the innocent bystanders allow the activity of evildoers, not merely because of fear and indifference, but because they gain vicarious pleasure from seeing others perform the wicked deeds which they themselves wish but fear to perform. She came eventually to see the passive virtuous people as guilty of promoting evil even when they do not consciously do so.

This theory about the relationship between saints and evildoers and their collusion in evil became her lifelong gospel, the subject of numerous informal talks, the message she preached from political platforms, and the basis of her interpretation of current events. (p. 316)

The same theory informed all her fiction. An early spare version of her theme appears in the short story "Magic." Here a maid, hoping to relax her mistress as she brushes her hair, tells a story of a villainous madam who cheats and bullies the prostitutes in a New Orleans brothel. The point of the story is that the madam's activity is made possible by those around her—the male clients, the police, and the cook—who do nothing. Not only are these people as guilty as the one who perpetrates the violence, but so too are the woman and the maid who relish the story. The woman sniffs scent (a detail which suggests her desire to hide the unpleasant realities), stares at her blameless reflection in the mirror, and urges the storyteller to continue whenever she pauses. Lest there be any doubt about the equation of guilt between both madams and both maids, they resemble each other so closely as to invite confusion…. The theme of the story echoes Porter's words that the evil of our time is not an accident but a total consent.

A fuller version of the theme appears in "Flowering Judas," which, like many of Porter's stories, has a triangular arrangement of characters, consisting of villain, victim, and "heroine." Braggioni, like all Porter's villains, is pure caricature and looms in the story like a grotesque Easter egg in shades of mauve and purple and yellow. A hideous creature with the eyes of a cat and the paunch of a pig, he embodies each of the seven deadly sins.

The implication of the story is that if Braggioni is a self-serving, self-indulgent villain, he has not always been so. Once he was a young idealist in both politics and love. It is Laura and people like her who have caused him to change from idealist to opportunist, and the main focus of the story is upon her and upon her motivation. (pp. 317-18)

Porter's longest treatment of her theme is, of course, Ship of Fools…. She said that her book was about the constant endless collusion between good and evil. She said that she believed human beings to be capable of total evil but thought that no one had ever been totally good, and that gave the edge to evil. She intended not to present any solution, but simply to show the principle at work and why none of us had an alibi in the world. (p. 318)

Again in the novel the villains are depicted in caricature. Herr Rieber is piglike and the Zarzuela Company, a group of thieves, pimps, and prostitutes who stop at nothing, is described as a flock of crows or other quarreling, thieving birds.

The pivotal character who corresponds with Laura of "Flowering Judas" is Dr. Shumann. He is well qualified by his superior intelligence and by his professional training to be influential, but he has developed a detachment which distances him from the others. He is introduced in the novel standing above the other characters to watch them come aboard. As he looks down from his elevated position his interest is clinical, aloof…. Typically, he soon loses interest, and it is apparent that his physical weakness of the heart is symptomatic of a corresponding spiritual weakness. He is a professional helper of mankind who gives help automatically but is incapable of love or involvement. (pp. 318-19)

[Similarly, the theme of her essay on the trial of Sacco and Vanzetti, The Never Ending Wrong,] is exactly that of the stories and the novel, the arrangement of characters in a triangle of villain, victim, and not-so-innocent hero/heroine, the same that appears in all her work.

The villains have all the recognizable porcine, complacent traits of such other villains as Braggioni and Herr Rieber. They are Governor Fuller, Judge Thayer …, and the Judges who preside over the trial of the picketers…. (p. 320)

Arrayed against these representatives of corrupt authority are all those who wish to help the victims and protest their unfair trial. On close inspection, however, they turn out like other of Porter's blameless people to be secretly in collusion with the villains and conspiring toward the same end. Chief among these are the Communists, represented by Rosa Baron. When Porter expressed the wish that the victims might be saved, she was astonished to hear Rosa Baron reply, "Why, what on earth good would they be to us alive?" And there are other protesters of dubious intention, notably the journalists who profit from the scenes of high emotion when the members of the victim's family appear…. The victims, of course, are not saved and they die, like Eugenio of "Flowering Judas" and Echegaray of Ship of Fools, with dignity and resignation gazing steadfastly at death. Their families are dazed and filled with horror, as are many of Porter's characters when they recognize the presence of Evil, "its power and its bestial imbecility." (pp. 320-21)