Driverless cars ponder who should die first

Left to right: From left to right, who respondents believed should be saved first (a baby) to last (a cat).

Are some lives worth more than others? The rapid development of self-driving technology is raising questions about who should be saved in car crashes, and bringing up old ethical dilemmas.

A self-driving car carrying a family of four is careening towards a brick wall. It can either stay on course and sacrifice its passengers, or swerve and hit a pedestrian. What should it do? Now, imagine the pedestrian is a violent criminal. Does that change your view? What if it’s a baby in a pushchair?

To help elucidate the problem, scientists have analysed more than 40 million responses to scenarios like this with their “Moral Machine”, an online game which puts players in the driving seat.

They were “trying to understand the kinds of moral decisions that driverless cars might have to resort to,” says researcher Edmond Awad.

The results reveal that we would prefer to save a baby above anyone else. A criminal is considered more valuable than a cat, but less so than a dog. While “large” people are less likely to be saved than an average person, their lives are valued above the homeless.

And there are cultural differences. In Western countries like the US, people were more likely to favour inaction and let the car stay on course, while those in Latin America prioritised saving the physically fit or high-status.

Across the globe, there was a trend towards saving the young over the old, females over males, and pedestrians over passengers.

These issues were first raised by the trolley problem, a classic ethical dilemma set out by philosopher Philippa Foot in 1967.

In the problem, a runaway tram is on course to hit five people who are tied to the tracks. You are standing next to a lever. If you pull it, the tram will be redirected on to a side track, but one person is tied down there. What do you do?

A person who subscribes to utilitarianism, which prioritises the outcome of a situation, would say five lives are worth more than one and pull the lever. By contrast, a deontologist would say it is best to do nothing because it is wrong to actively kill.

While these questions sound hypothetical, the reality may not be far off. Germany has already introduced a law stating that driverless cars must never decide who to save based on age, gender or health.

Are some lives worth more than others?


Every life is equally precious, say some. It is morally wrong to say that someone is less deserving of life because they are old or homeless or have a criminal past. If we start making judgements about who is more valuable, we may reach a place where the rich and powerful are saved over the poor.

Don’t be naive, reply others. It is clearly better for a murderer to die than a doctor who will go on to save many lives. Surely, too, it is better for an elderly man who has lived a rich and full life to die in the place of a baby who is full of potential. It’s best to admit this.

You Decide

  1. Should we fear the future of self-driving cars?
  2. Is one life ever worth more than another?


  1. Look at the graphic at the top of this article. Take the types of people listed and put them in order of who you think it is most to least important to save. Think about how you can justify your decision. Then, get into pairs and compare your lists. How different are they from our graphic, and from each other’s?
  2. Read up about the trolley problem, utilitarianism and deontology. Write a page with a full explanation of what course of action you think is right, using ethical theories to support your thinking.

Some People Say...

“Ethics is knowing the difference between what you have a right to do and what is right to do.”

Potter Stewart

What do you think?

Q & A

What do we know?
The Massachusetts Institute of Technology (MIT) has created a “Moral Machine” to study which lives people think are the most worthy of saving in a car accident with two possible outcomes. The study is meant to show the kinds of ethical decisions that self-driving cars may soon have to make. For example, whether to allow its driver to die in a crash in order to save pedestrians. The results show people generally favour saving the young over the old.
What do we not know?
Whether these dilemmas will ever be played out in real life. Karl Iagnemma, the president of Aptiv Automated Mobility, has downplayed the importance of working out how a driverless car should behave in these situations because “the incident of events like this is vanishingly small.”

Word Watch

Make something clear or explain it.
The research was carried out by the Massachusetts Institute of Technology and translated into a graph by the World Economic Forum.
The trolley problem
A variation of this problem involves the choice of whether to push a fat man onto the tracks to save the five people. This can provoke different responses as many people view this as more active murder than pulling the lever.
An ethical theory that states that the correct course of action is the one that results in “the greatest good for the greatest number”. In other words, that the end justifies the means.
An ethical theory that focuses on the morality of actions themselves, rather than their consequences. This means that there are some actions, like murder, that you should never do regardless of the results.
An imagined situation to test a theory, rather than something real.

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