Other recent research shows similar results: stressing subjects, rushing them or reminding them of their mortality all reduce utilitarian responses, most likely by preventing them from controlling their emotions.

Even the way a scenario is worded can influence our judgments, as lawyers and politicians well know. In one study, subjects read a number of variations of the classic trolley dilemma: should you turn a runaway trolley away from five people and onto a track with only one? When flipping the switch was described as saving the people on the first track, subjects tended to support it. When it was described as killing someone on the second, they did not. Same situation, different answers.

And other published studies have shown that our moods can make misdeeds seem more or less sinful. Ethical violations become less offensive after people watch a humor program like “Saturday Night Live.” But they become more offensive after reading “Chicken Soup for the Soul,” which triggers emotional elevation, or after smelling a mock-flatulence spray, which triggers disgust.

The scenarios in these papers are somewhat contrived (trolleys and such), but they have real-world analogues: deciding whether to fire a loyal employee for the good of the company, or whether to donate to a single sick child rather than to an aid organization that could save several.

Regardless of whether you endorse following the rules or calculating benefits, knowing that our instincts are so sensitive to outside factors can prevent us from settling on our first response. Objective moral truth doesn’t exist, and these studies show that even if it did, our grasp of it would be tenuous.

But we can encourage consistency in moral reasoning by viewing issues from many angles, discussing them with other people and monitoring our emotions closely. In recognizing our psychological quirks, we just might find answers we can live with.