People often act out of self-interest.

The characters in the story act in their own self-interests. Within the power structure of the penal colony, the people follow the lead of the Commandant. It is in their best interest to do so, and the Officer is the only one who resists the authority of the current Commandant. The audiences for the executions have dwindled away, indicating that popular support has shifted to the new leader. In the tearoom toward the end of the story, the residents of the colony express derision for the old Commandant, revealing that any show of support from the community was likely a sham, motivated by fear and a sense of self-preservation against a brutal regime.

The Traveler also behaves in his own best interest. Although he is horrified by the lack of a justice system that allows for errors in accusation and does not permit accused men to hear the charges against them or defend themselves, he does nothing. Because he is an outsider under the protection of the new Commandant, he feels no need to fake support for the Officer’s practices. However, he does not get actively involved or try to be a part of any change to the system. Even though he knows he’s supposed to speak with the new Commandant and offer an opinion on the Officer’s practices and the use of the apparatus, he does not do so. Instead, after witnessing the Officer’s suicide in the apparatus, he continues his observations to satisfy his own curiosity by going to the old Commandant’s grave. Upon finding the inscription with the prophecy the old Commandant will rise again and reinstate his barbaric system of government, the Traveler decides to leave immediately in an act of blatant self-preservation. He leaves the island behind in order to remove himself from an uncomfortable situation.

The values of traditions and customs are subjective.

The Officer reveres his traditions without ever regarding them objectively. He wears a heavy, hot uniform in a tropical climate because it represents the customs of his homeland even though, as the Traveler observes, it must be uncomfortable. The Officer also supports and oversees a deeply flawed judicial system because he reveres the traditional authority figure who designed and implemented it. Even though support has dwindled away, the Officer’s belief in and love for the old traditions holds strong. In his description of public executions, the Officer’s perspective is that the public gathered to watch in rapture as the apparatus did its work. The Officer is so overcome with emotion as he describes the executions that he embraces the Traveler, certain that his companion is equally in subjective awe of the excellence and majesty of the apparatus.  

The Officer erroneously believes the apparatus and the system it represents are objectively good and just, but various factors emphasize how the value of his traditions and customs are, in fact, subjective. The new Commandant does not support existing judicial traditions and has denied funding that would provide replacement parts for the aging apparatus. No one attends the executions since the death of the old Commandant, implying that attendance under his leadership was compulsory rather than voluntary. Additionally, the former Commandant was not permitted to be laid to rest in the cemetery but is interred beneath the floor of a tearoom and mocked by the local residents, indicating an objective repudiation of the traditions and customs he created. Finally, the cornerstone of the Officer’s faith in the tradition of the apparatus, the perceived enlightenment after hours of torture, fails when he himself goes under, demonstrating that traditions and customs should be regarded with a healthy measure of skepticism, logic, and objectivity.

Evil can be banal in nature.

The matter-of-fact tone with which the Officer describes the objectively evil system he serves emphasizes how deeply ingrained his belief is, and how plainly he sees his actions as good. The Officer describes the execution process to the Traveler with no apologies or excuses because, to the Officer, it needs none. The Officer is more concerned with the squeaking of the apparatus and the fact that he can no longer get replacement parts to keep it in good working order than he is with the condemned man himself. When the condemned man vomits in terror, the Officer focuses on the fact that his beloved machine is soiled. His release of the condemned man has nothing to do with justice or even mercy but rather the Officer’s own twisted beliefs about the system and his mundane role within it.

The Traveler also views the Officer’s actions as boring, showing that he is the sort of person who perpetuates evil through his own lack of interest. Like the Officer, the Traveler is more interested in the apparatus than he is with the condemned man. He does not even regard the condemned man as an individual. It is only when the Officer describes the lack of a true justice system that the Traveler begins to understand the evil at hand. Still, he does nothing to advocate for the condemned man or intercede on his behalf. Instead, he stands by as an observer, rationalizing that there is nothing he can do to make any changes in the situation. After the Officer’s death, the Traveler continues as a bystander because he does not go back to the Commandant to make a report, nor does he do anything to assist the condemned man or the soldier. The Traveler’s final action is to flee the scene, demonstrating his unwillingness to take any action against the horrors he’s witnessed.