But the trolley problem can be a double-edged sword, Lin says. On the one hand, it’s a great entry point and teaching tool for engineers with no background in ethics. On the other hand, its prevalence, whimsical tone, and iconic status can shield you from considering a wider range of dilemmas and ethical considerations. Lin has found that delivering the trolley problem in its original form—streetcar hurtling towards workers in a strangely bare landscape—can be counterproductive, so he often re-formulates it in terms of autonomous cars:
You’re driving an autonomous car in manual mode—you’re inattentive and suddenly are heading towards five people at a farmer’s market. Your car senses this incoming collision, and has to decide how to react. If the only option is to jerk to the right, and hit one person instead of remaining on its course towards the five, what should it do?
It may be fortuitous that the trolley problem has trickled into the world of driverless cars: It illuminates some of the profound ethical—and legal—challenges we will face ahead with robots. As human agents are replaced by robotic ones, many of our decisions will cease to be in-the-moment, knee-jerk reactions. Instead, we will have the ability to premeditate different options as we program how our machines will act. For philosophers like Lin, this is the perfect example of where theory collides with the real world—and thought experiments like the trolley problem, though they may be abstract or outdated, can help us to rigorously think through scenarios before they happen. Lin and Gerdes hosted a conference about ethics and self-driving cars last month, and hope the resulting discussions will spread out to other companies and labs developing these technologies.
But could trolley problems, beyond helping us to design technology, also serve as a tool for everyday self-improvement? The philosopher and psychologist Eric Schwitzgebel, who has studied the behavior of ethics professors, found that philosophical expertise does little to change their moral behavior—for example, they’re no more likely than others of similar social background to donate to charity or stop eating meat. Schwitzgebel doubts that spending time puzzling over trolleys can actually help a person make better moral decisions. But he still thinks it’s useful to hold onto thought exercises like the trolley for research purposes, even if they don’t really seem to change the way people behave in the real world, or are an imperfect analogue to the messy decisions they typically face.
“We as psychologists and experimental philosophers should be pretty careful about how subjects are interpreting [the trolley problem],” Schwitzgebel told me, “and there is a certain lack of external validity to it. On the other hand, it’s a nice, clean problem.” This simplicity, Schwitzgebel believes, is what makes it such an incisive tool for scientific investigation. Scientists still need the trolley problem, in addition to more realistic scenarios, he said, because “basic research into morality is an important part of the human condition.”
It’s hard to tell if this means the trolley problem will make another resurgence, though Judith Thomson herself wrote to me in an email: “I don’t for a moment think the trolley problem is approaching its end.”
As for the rest of us, who may be weary from wondering why we couldn’t just warn the workers to get out of the way and avoid the whole mess in the first place, my advice is this: Just keep sipping your latte.