Smart Cars and the Trolly Dilemma

The Trolly Dilemma & Jewish Law

December, 2017

On July 26, 2013, The Wall Street Journal published a story about the ethical dilemmas facing Google and other companies working on “driverless cars.” It is only a matter of time before these cars, which are already being tested, are on the road. The cars have computers with built-in algorithms that are designed to respond to any scenario—a speeding car, oncoming traffic, yellow lights, bikers.

But how should they be programmed to respond when faced with a choice that has no clear moral outcome? What if a driverless car needs to choose between swerving so as to avoid a crowd and plowing into a smaller group of people?

Several years ago I came across a book by Harvard professor Michael J. Sandel, who has invested a great deal of time and effort exploring the subject of justice as it pertains to these intriguing, often disturbing, ethical dilemmas. His bestselling book Justice: What’s the Right Thing to Do? is a fascinating study of our moral compass and how we might handle the many situations he paints on the canvas of “What if?” His thinking has inspired many, which is evident from the fact that a video of one of his lectures pulled in over five million viewers.

As I read parts of his book, I thought not so much about how I would deal with these situations but about what halachah would say.

One of his dilemmas mirrors the problem Google is now facing. Let us briefly review it, consider his students’ response, and discover an inherent contradiction that it presents. We will then review the halachic key to both the dilemma and the contradiction.

A writer for The Atlantic Monthly discusses a lecture given by Sandel, who presented this scenario: “Suppose you’re the driver of a trolley car, and your trolley car is hurtling down the track at 60 miles an hour. You notice five workers working on the track. You try to stop but you can’t because your brakes don’t work. You know that if you crash into these five workers, they will all die. You feel helpless until you notice that off to the side, there’s a side track. And there’s one worker on the side track.

“The question: Do you send the trolley onto the side track, thus killing the one worker but sparing the five, or do you let events unfold as they will and allow the deaths of all five?”

Then Sandel asked about a popular variation of the problem. “The same trolley is careening toward unsuspecting innocents, but this time you’re an onlooker on a footbridge, and you notice that standing next to you, leaning over the bridge, is a very heavy man.

“You could give him a shove. He would fall over onto the track, right in the way of the trolley car. He would die, but he would spare the five. How many would push the [heavy] man over the bridge?”

A few hands went up.

“And that’s exactly why,” Sandel concluded, “some scientists argue that this well-known ‘trolley dilemma’ shouldn’t be used for psychology experiments as much as it is.”

How could it be, many scientists wonder, that while most people would cause the trolley to veer, only 11 percent would push the man to save the many? Don’t they both involve the very same moral dilemma?

Many explanations have been offered, none of which satisfied me. However, halachic history may hold the key to this inconsistency.

Shmuel II (20) tells us that Serach bas Asher, who was 684 years old, made a deal with Dovid Hamelech’s general that instead of killing many of the inhabitants of her town, they would kill the one man who was guilty of rebelling against the king—Sheva ben Bichri—and deliver his head. From here it is derived that one may hand over one (guilty) person to the authorities to be killed in order to save many (innocents). The Gemara² debates whether this principle would apply in a case where handing over an innocent person would save the lives of many.³

The Rambam rules famously⁴ that one may hand over only a guilty person in order to save the many. Many disagree with Rambam, and indeed, Rama⁵ mentions both views.

The Tzitz Eliezer cites a discussion found in the writings of the Chazon Ish,⁶ who wonders about a case strikingly similar to the trolley scenario. If an arrow is heading toward a group of people and will certainly kill them, and one has the opportunity to divert it so that it will kill only one person, what should he do?

Much of the halachic discussion hinges upon how action is defined. As we know from hilchos Shabbos, not all actions are equal. There are gramas, koach sheni, psik reisha, and others—various forms of indirect or noncommittal action, not all of which are actually deemed actions by Torah law.

The Chazon Ish suggests that one who diverts the arrow can consider this not as the killing of one but as the saving of many. In other words, it is not comparable to handing a person over to be killed because the diversion of the trolley/arrow can be viewed as a unique manipulation of the laws of physics in order to save people. The ultimate result of this act of salvation may not be our concern.

Yet the Chazon Ish was hesitant; after all, the case of the trolley/arrow may be worse in that we are causing death by our action, as opposed to simply handing someone over to death. There is no precedent to allow actually killing someone!⁷

The Tzitz Eliezer is more certain. He proves that inaction, the principle of “Shev v’al taaseh (sit and do nothing),” is better, implying that in such a case, an “error” of omission is always safer than one of commission.

Returning to Dr. Sandel’s trolley paradox presented in The Atlantic Monthly, perhaps inherent in our moral compass is the sense that flicking a switch—similar to handing someone over—is much less of a concern than actually murdering someone with our own hands in order to save others.  One is an act of murder, while the other is closer to an indirect result.

It would seem that the Chazon Ish would agree that pushing the man over the bridge to stop the trolley would be forbidden, and that it is certainly different from the original scenario, in which the choice would be to divert the path of the trolley.⁸

Based on halachic compartmentalization, then, it appears that there is really no inconsistency in this moral dilemma and that the students at Harvard were on to something when they differentiated between hitting a switch and pushing a man.

(According to some,⁹ non-Jews must look to halachah as their guide in determining how to observe the sheva mitzvos bnei Noach. Perhaps, then, Hashem implanted in their psyches a moral sense that enables them to inherently feel what may take us years of study.)

Sadly, in Dr. Sandel’s brilliant book on ethical dilemmas, I saw not one mention of the Talmud. It is my hope that Dr. Sandel, who is a Jew, will someday discover the beauty and realism that is halachah—and the heritage that no doubt imbued him with the exquisite sensitivity with which he has been marveling at the world.

As for driverless cars, perhaps, like many modern ovens, they will one day come with a “halachah mode”!