For Yank, "Direct Action" is impossible because he has no relationship or communication with his superiors. The whistle-blower that commands the workers to keep moving is hidden in darkness above the stokehole and the Engineers that escort Mildred have no verbal communication with Yank. Authority on board the Ocean Liner is faceless and nameless—not a negotiable or, in the case of the whistle-blower, even a human presence.
As is apparent in Scene seven, Yank does not understand the concept of "direct action." He wants to join the I.W.W. because he thinks they use destructive means to gain worker rights. Senator Queen's speech, read from a paper by one of his inmates, characterizes the group as dangerous, forceful and explosive—all attractive to Yank. Queen describes them as an "ever-present dagger pointed at the heart of the greatest nation the world has ever known" and the "International Wreckers of the World." Yank also feels a special kinship to the Wobblies because Senator Queen remarks that the group would degenerate modern American society "back to the ape."
Yank transitions from the "ape" to the "thinker" in Scene Six. After he hears that the Wobblies described as making men like apes, men like him, he takes the paper and sits in the "attitude of Rodin's 'The Thinker.'" As Yank sits there he suddenly jumps up as if "some appalling thought had crushed on him." Yank rejects his identity as an "ape." This is a major change from the beginning of the scene where he identifies himself to the other inmates as the "ape" and thinks he is in a Zoo. Yank realizes that he is not an ape, but a person caged and imprisoned into a social identity by companies like Steel Trust. While this thought makes Yank realize he is not a wild animal it inspires him to act like one, and bend back the bars of his cage.