It’s Time To Pull The Switch On The Trolley Problem

Back in August Germany became the first nation to institute federal guidelines for self-driving cars. These guidelines include criteria for what to do in the case of an impending accident when split-second decisions have to be made. Built into these criteria are a set of robust moral values, including mandating that self-driving cars will prioritize human lives over the lives of animals or property, and that the cars are not allowed to discriminate between humans on the basis of age, gender, race or disability.

Philosophers have an obvious interest in these sorts of laws and the moral values implicit in them. Yet in spite of the wide range of potentially interesting problems such technology and legislation pose, one perennial topic seems to dominate the discussion both amongst philosophers and the popular press: The Trolley problem. So electrifying has this particular problem become that I suspect I don’t need to rehash the details, but just in case, here is the basic scenario: a run-away trolley is hurtling down the tracks towards five people. You can save the five by throwing a switch diverting the trolley to a side track, where there is only one person. Should you throw the switch, saving the five and sacrificing the one, or should you do nothing, letting the one live and letting the five die?

Initially developed over 60 years ago by Philippa Foot and modulated dozens of times in the intervening decades, the Trolley problem was long a staple of intro to ethics courses, good for kick starting some reflection and conversation on the value of life and the nature of doing vs. allowing. Hence, you could practically feel philosophy departments all over the world jump for joy when they realized this abstract thought experiment finally manifest itself in concrete, practical terms due to the advent of self-driving cars.

This excitement fused with some genuinely fascinating work in the neuroscience of moral decision making. The work of scholars like Josh Green has provided genuine insight into what occurs in our brains when we have to make decisions in trolley-like situations. Out of the marriage of these two developments—along with some midwifery from psychology and economics—the field of ‘trolleyology’ was born. And it is my sincere hope that we can kill this nascent field in its crib.

Why should I, as an ethicist, have such a morbid wish for something that is clearly a boon to my discipline? Because despite the superficial appeal there is really not very much to it as far as a practical problem goes. It is marginally useful for eliciting conflicting (perhaps even logically incompatible) intuitions about how the value of life relates to human action, which is what makes it a useful tool for the aforementioned intro to ethics courses. But the Trolley problem does precious little for illuminating actual moral decision making, regardless of whether you’re in a lecture hall or an fMRI.

To see this, take a brief moment to reflect on your own life. How many times have you ever had to decide between the lives of a few against the lives of the many? For that matter, take ‘life’ out of the equation: how many times have you had to make a singular, binary decision between the significant interests of one person against the similar interests of multiple people? Actual human beings face real-world moral decisions every day, from the food choices we make and the the products we purchase, to the ways we raise our children and how we respond to the needs of strangers. Almost none of these decisions share the forced binary, clear 1-vs.-5 structure of a trolley problem.1

What then of the self-driving car example I opened with? Does this not demonstrate the pragmatic value of fretting over the Trolley problem? Won’t the ‘right’ answer to the Trolley problem be crucial for the moral operation of billions of self-driving cars in the future to come? In short, no. Despite all the press it has gotten, there is no good reason to think the development of self-driving cars requires us to solve the Trolley problem any more than the development of actual trolleys required it almost 200 years ago. Again, check your own experience: how often behind the wheel of a car did you—or for that matter anyone you know, met, or even read about—ever have to decide between veering left and killing one or veering right and killing five? If humans don’t encounter this problem when driving, why presume that machines will?

In fact, there’s very good reason to think self-driving cars will be far less likely to encounter this problem than humans have. Self-driving cars have sensors that are vastly superior to human eyes—they encompass a 360-degree view of the car, never blink, tire or get distracted, and can penetrate some obstacles that are opaque to the human eye. Self-driving cars can also be networked with each other meaning that what one car sees can be relayed to other cars in the area, vastly improving situational awareness. In the rare instances where a blind spot occurs, the self-driving car will be far more cognizant of the limitation and can take precautionary measures much more reliably than a human driver. Moreover, since accidents will be much rarer when humans are no longer behind the wheel, much of the safety apparatus that currently exists in cars can be retooled with a mind to avoiding situations where this kind of fatal trade off occurs.2

Both human beings and autonomous machines face an array of serious, perplexing and difficult moral problems.3 Few of them have the click-bait friendly sex appeal of the trolley problem. It should be the responsibility of philosophers, psychologists, neuroscientists, A.I.-researchers, and journalists to engage the public on how we ought to address those problems. But it is very hard to do that when trolleyology is steering their attention in the wrong direction.

Garret Merriam

Department of Philosophy

Sacramento State

[1] There are noteworthy exceptions, of course. During World War II, Winston Churchill learned of an impending attack on the town of Coventry and he decided not to warn the populace, for fear of tipping the Germans that their Enigma code had been cracked by the British. 176 people died in the bombing, but the tactical value of preserving access to German communications undoubtedly saved many more by helping the Allies to win the war. If you’re like most people, you can be thankful that you never have to make a decision like this one.

[2] For example, much of the weight of the car comes from the steal body necessary to keep the passengers safe in the event of a pileup or a roll-over. As the likelihood of those kinds of accidents become statistically insignificant this weight can be largely removed, lowering the inertia of the car making it easier to stop quickly (and more fuel efficient, to boot), thus avoiding the necessity of trolley-type decisions.

[3] Take, for example, the ethics of autonomous drone warfare. Removing human command and control of drones and replacing it with machine intelligence might vastly reduce collateral damage as well as PTSD in drone pilots. At the same time, however, it even further lowers valuable inhibitions against the use of lethal force, and potentially creates a weapon that oppressive regimes—human controlled or otherwise—might use indiscriminately against civilian populations. Yet a google search for “autonomous military drones” yields a mere 6,410 hits, while “autonomous car” + “trolley problem” yields 53,500.