Some studies show that people maintain a kind of moral equilibrium, meaning that giving money to charity may lead them to skimp on the tip at dinner, whereas partying too much may inspire a volunteer day at the soup kitchen.
But other studies found just the opposite: Behaving ethically leads people to more good deeds later, said study co-author, Gert Cornelissen, a psychologist at the University Pompeu Fabra in Spain.
To sort out this conflicting picture, Cornelissen and his colleagues asked 84 undergraduates what they would do in a hypothetical dilemma where a runaway trolley is on a collision course with five people, and the only way to save them is to flip a switch, reroute the trolley and kill one person.
People who would flip the switch were considered to have outcome-based morality, where the end results (saving four lives), not the actions (causing one person's death), matter most. Those in the opposite group were assumed to base their morality on rules, such as "deliberate killing is always wrong."
Half of the participants were then asked to remember a time they behaved ethically, while the other group remembered past unethical behavior. They then asked participants to share a pot of money with partners.
Those who had an ends-justify-the-means mindset were likelier to be stingier with others if they were reminded of their past good deeds and more generous if they recalled past unethical behavior. By contrast, those who tended towards rules-based morality showed the opposite trend, suggesting that past good deeds or bad deeds were prompting similar behavior later on.
The "trolley problem," originally introduced by philosopher Philippa Foot in 1967, is a topic I've encountered before (in discussion, not in practice), and I've never felt particularly more inclined toward one action over the other. When it comes to "five lives versus one life," I would tend to respond with "depends on the lives"—I don't feel that five lives are necessarily worth fives times as much as one life. But that's not part of the scenario. All you're meant to go on is the numbers, in which case I don't feel there is enough data to make a morally informed decision, and so I don't regard either option as more morally compelling than the other. Any choice I made in this situation would be, to me, arbitrary and amoral. That said, probably 7 times out of 10, I would opt to stay the course, simply because, in the interest of limiting arbitrary actions, I tend to the default, if one exists. Those 3 times that I would reroute the trolley, meanwhile, would account for those periodically spontaneous moods of mine, when I will opt to do something just for the sake of doing something over doing nothing.