What moral decisions should driverless cars make Iyad Rahwan
Today I’m going to talk
about technology and society.
The Department of Transport
estimated that last year
35,000 people died
from traffic crashes in the US alone.
Worldwide, 1.2 million people
die every year in traffic accidents.
If there was a way we could eliminate
90 percent of those accidents,
would you support it?
Of course you would.
This is what driverless car technology
promises to achieve
by eliminating the main
source of accidents –
human error.
Now picture yourself
in a driverless car in the year 2030,
sitting back and watching
this vintage TEDxCambridge video.
(Laughter)
All of a sudden,
the car experiences mechanical failure
and is unable to stop.
If the car continues,
it will crash into a bunch
of pedestrians crossing the street,
but the car may swerve,
hitting one bystander,
killing them to save the pedestrians.
What should the car do,
and who should decide?
What if instead the car
could swerve into a wall,
crashing and killing you, the passenger,
in order to save those pedestrians?
This scenario is inspired
by the trolley problem,
which was invented
by philosophers a few decades ago
to think about ethics.
Now, the way we think
about this problem matters.
We may for example
not think about it at all.
We may say this scenario is unrealistic,
incredibly unlikely, or just silly.
But I think this criticism
misses the point
because it takes
the scenario too literally.
Of course no accident
is going to look like this;
no accident has two or three options
where everybody dies somehow.
Instead, the car is going
to calculate something
like the probability of hitting
a certain group of people,
if you swerve one direction
versus another direction,
you might slightly increase the risk
to passengers or other drivers
versus pedestrians.
It’s going to be
a more complex calculation,
but it’s still going
to involve trade-offs,
and trade-offs often require ethics.
We might say then,
“Well, let’s not worry about this.
Let’s wait until technology
is fully ready and 100 percent safe.”
Suppose that we can indeed
eliminate 90 percent of those accidents,
or even 99 percent in the next 10 years.
What if eliminating
the last one percent of accidents
requires 50 more years of research?
Should we not adopt the technology?
That’s 60 million people
dead in car accidents
if we maintain the current rate.
So the point is,
waiting for full safety is also a choice,
and it also involves trade-offs.
People online on social media
have been coming up with all sorts of ways
to not think about this problem.
One person suggested
the car should just swerve somehow
in between the passengers –
(Laughter)
and the bystander.
Of course if that’s what the car can do,
that’s what the car should do.
We’re interested in scenarios
in which this is not possible.
And my personal favorite
was a suggestion by a blogger
to have an eject button in the car
that you press –
(Laughter)
just before the car self-destructs.
(Laughter)
So if we acknowledge that cars
will have to make trade-offs on the road,
how do we think about those trade-offs,
and how do we decide?
Well, maybe we should run a survey
to find out what society wants,
because ultimately,
regulations and the law
are a reflection of societal values.
So this is what we did.
With my collaborators,
Jean-François Bonnefon and Azim Shariff,
we ran a survey
in which we presented people
with these types of scenarios.
We gave them two options
inspired by two philosophers:
Jeremy Bentham and Immanuel Kant.
Bentham says the car
should follow utilitarian ethics:
it should take the action
that will minimize total harm –
even if that action will kill a bystander
and even if that action
will kill the passenger.
Immanuel Kant says the car
should follow duty-bound principles,
like “Thou shalt not kill.”
So you should not take an action
that explicitly harms a human being,
and you should let the car take its course
even if that’s going to harm more people.
What do you think?
Bentham or Kant?
Here’s what we found.
Most people sided with Bentham.
So it seems that people
want cars to be utilitarian,
minimize total harm,
and that’s what we should all do.
Problem solved.
But there is a little catch.
When we asked people
whether they would purchase such cars,
they said, “Absolutely not.”
(Laughter)
They would like to buy cars
that protect them at all costs,
but they want everybody else
to buy cars that minimize harm.
(Laughter)
We’ve seen this problem before.
It’s called a social dilemma.
And to understand the social dilemma,
we have to go a little bit
back in history.
In the 1800s,
English economist William Forster Lloyd
published a pamphlet
which describes the following scenario.
You have a group of farmers –
English farmers –
who are sharing a common land
for their sheep to graze.
Now, if each farmer
brings a certain number of sheep –
let’s say three sheep –
the land will be rejuvenated,
the farmers are happy,
the sheep are happy,
everything is good.
Now, if one farmer brings one extra sheep,
that farmer will do slightly better,
and no one else will be harmed.
But if every farmer made
that individually rational decision,
the land will be overrun,
and it will be depleted
to the detriment of all the farmers,
and of course,
to the detriment of the sheep.
We see this problem in many places:
in the difficulty of managing overfishing,
or in reducing carbon emissions
to mitigate climate change.
When it comes to the regulation
of driverless cars,
the common land now
is basically public safety –
that’s the common good –
and the farmers are the passengers
or the car owners who are choosing
to ride in those cars.
And by making the individually
rational choice
of prioritizing their own safety,
they may collectively be
diminishing the common good,
which is minimizing total harm.
It’s called the tragedy of the commons,
traditionally,
but I think in the case
of driverless cars,
the problem may be
a little bit more insidious
because there is not necessarily
an individual human being
making those decisions.
So car manufacturers
may simply program cars
that will maximize safety
for their clients,
and those cars may learn
automatically on their own
that doing so requires slightly
increasing risk for pedestrians.
So to use the sheep metaphor,
it’s like we now have electric sheep
that have a mind of their own.
(Laughter)
And they may go and graze
even if the farmer doesn’t know it.
So this is what we may call
the tragedy of the algorithmic commons,
and if offers new types of challenges.
Typically, traditionally,
we solve these types
of social dilemmas using regulation,
so either governments
or communities get together,
and they decide collectively
what kind of outcome they want
and what sort of constraints
on individual behavior
they need to implement.
And then using monitoring and enforcement,
they can make sure
that the public good is preserved.
So why don’t we just,
as regulators,
require that all cars minimize harm?
After all, this is
what people say they want.
And more importantly,
I can be sure that as an individual,
if I buy a car that may
sacrifice me in a very rare case,
I’m not the only sucker doing that
while everybody else
enjoys unconditional protection.
In our survey, we did ask people
whether they would support regulation
and here’s what we found.
First of all, people
said no to regulation;
and second, they said,
“Well if you regulate cars to do this
and to minimize total harm,
I will not buy those cars.”
So ironically,
by regulating cars to minimize harm,
we may actually end up with more harm
because people may not
opt into the safer technology
even if it’s much safer
than human drivers.
I don’t have the final
answer to this riddle,
but I think as a starting point,
we need society to come together
to decide what trade-offs
we are comfortable with
and to come up with ways
in which we can enforce those trade-offs.
As a starting point,
my brilliant students,
Edmond Awad and Sohan Dsouza,
built the Moral Machine website,
which generates random scenarios at you –
basically a bunch
of random dilemmas in a sequence
where you have to choose what
the car should do in a given scenario.
And we vary the ages and even
the species of the different victims.
So far we’ve collected
over five million decisions
by over one million people worldwide
from the website.
And this is helping us
form an early picture
of what trade-offs
people are comfortable with
and what matters to them –
even across cultures.
But more importantly,
doing this exercise
is helping people recognize
the difficulty of making those choices
and that the regulators
are tasked with impossible choices.
And maybe this will help us as a society
understand the kinds of trade-offs
that will be implemented
ultimately in regulation.
And indeed, I was very happy to hear
that the first set of regulations
that came from
the Department of Transport –
announced last week –
included a 15-point checklist
for all carmakers to provide,
and number 14 was ethical consideration –
how are you going to deal with that.
We also have people
reflect on their own decisions
by giving them summaries
of what they chose.
I’ll give you one example –
I’m just going to warn you
that this is not your typical example,
your typical user.
This is the most sacrificed and the most
saved character for this person.
(Laughter)
Some of you may agree with him,
or her, we don’t know.
But this person also seems to slightly
prefer passengers over pedestrians
in their choices
and is very happy to punish jaywalking.
(Laughter)
So let’s wrap up.
We started with the question –
let’s call it the ethical dilemma –
of what the car should do
in a specific scenario:
swerve or stay?
But then we realized
that the problem was a different one.
It was the problem of how to get
society to agree on and enforce
the trade-offs they’re comfortable with.
It’s a social dilemma.
In the 1940s, Isaac Asimov
wrote his famous laws of robotics –
the three laws of robotics.
A robot may not harm a human being,
a robot may not disobey a human being,
and a robot may not allow
itself to come to harm –
in this order of importance.
But after 40 years or so
and after so many stories
pushing these laws to the limit,
Asimov introduced the zeroth law
which takes precedence above all,
and it’s that a robot
may not harm humanity as a whole.
I don’t know what this means
in the context of driverless cars
or any specific situation,
and I don’t know how we can implement it,
but I think that by recognizing
that the regulation of driverless cars
is not only a technological problem
but also a societal cooperation problem,
I hope that we can at least begin
to ask the right questions.
Thank you.
(Applause)