I have been following the discussion about the ethics of the driverless car with some interest. This is close to a contemporary restatement of the infamous trolley problem but here we are instructing a trolley in a difficult decision: if I can save more lives by taking lives, should I do it? In the case of a driverless car, should the car take action that could kill the driver if, in doing so, it is far more likely to save more lives than would be lost?
While I find the discussion interesting, I worry that such discussion makes people unduly worried about driverless cars, potentially to a point that will delay adoption. Let’s look into why I think that. (I’m not going to go into whether cars, themselves, are a good or bad thing.)
Many times, the reason for a driverless car having to make such a (difficult) decision is that “a person leaps out from the kerb” or “driving conditions are bad” and “it would be impossible to stop in time.”
As noted in CACM:
The driverless cars of the future are likely to be able to outperform most humans during routine driving tasks, since they will have greater perceptive abilities, better reaction times, and will not suffer from distractions (from eating or texting, drowsiness, or physical emergencies such as a driver having a heart attack or a stroke).
In every situation where a driverless car could encounter a situation that would require such an ethical dilemma be resolved, we are already well within the period at which a human driver would, on average, be useless. When I presented the trolley problem, with driverless cars, to my students, their immediate question was why a dangerous situation had arisen in the first place? If the car was driving in a way that it couldn’t stop in time, there’s more likely to be a fault in environmental awareness or stopping-distance estimation.
If a driverless car is safe in varied weather conditions, then it has no need to be travelling at the speed limit merely because the speed limit is set. We all know the mantra of driving: drive to the conditions. In a driverless car scenario, the sensory awareness of the car is far greater than our own (and we should demand that it was) and thus we will eliminate any number of accidents before we arrived at an ethical problem.
Millions of people are killed in car accidents every year because of drink driving and speeding. In Victoria, Australia, close to 40% of accidents are tied to long distance driving and fatigue. We would eliminate most, if not all, of these deaths immediately with driverless technology adopted en masse.
What about people leaping out in front of the car? In my home city, Adelaide, South Australia, the average speed across the city is just under 30 kilometres per hour, despite the speed limit being 50 (traffic lights and congestion has a lot to do with this). The average human driver takes about 1.5 seconds to react (source), then braking deceleration is about 7 metres per second per second, less effectively in the wet. From that source, the actual stopping part of the braking, if we’re going 30km/h, is going to be less than 9 metres if it’s dry, 13 metres if wet. Other sources note that, with human reactions, the minimum overall braking is about 12 metres, 6 of which are braking. The good news is that 30km/h is already the speed at which only 10% of pedestrians are killed and, given how quickly an actively sensing car could react and safely coordinate braking without skidding, the driverless car is incredibly unlikely to be travelling fast enough to kill someone in an urban environment and still be able to provide the same average speed as we had.
The driverless car, without any ethics beyond “brake to avoid collisions”, will be causing a far lower level of injury and death. They don’t drink. They don’t sleep. They don’t speed. They will react faster than humans.
(That low urban speed thing isn’t isolated. Transport for London estimate the average London major road speed to be around 31 km/h, around 15km/h for Central London. Central Berlin is about 24 km/h, Warsaw is 26. Paris is 31 km/h and has a fraction of London’s population, about twice the size of my own city.)
Human life is valuable. Rather than focus on the impact on lives that we can see, as the Trolley Problem does, taking a longer view and looking at the overall benefits of the driverless car quickly indicates that, even if driverless cars are dumb and just slam on the brakes, the net benefit is going to exceed any decisions made because of the Trolley Problem model. Every year that goes by without being able to use this additional layer of safety in road vehicles is costing us millions of lives and millions of injuries. As noted in CACM, we already have some driverless car technologies and these are starting to make a difference but we do have a way to go.
And I want this interesting discussion of ethics to continue but I don’t want it to be a reason not to go ahead, because it’s not an honest comparison and saying that it’s important just because there’s no human in the car is hypocrisy.
I wish to apply the beauty lens to this. When we look at a new approach, we often find things that are not right with it and, given that we have something that works already, we may not adopt a new approach because we are unsure of it or there are problems. The aesthetics of such a comparison, the characteristics we wish to maximise, are the fair consideration of evidence, that the comparison be to the same standard, and a commitment to change our course if the evidence dictates that it be so. We want a better outcome and we wish to make sure that any such changes made support this outcome. We have to be honest about our technology: some things that are working now and that we are familiar with are not actually that good or they are solving a problem that we might no longer need to solve.
Human drivers do not stand up to many of the arguments presented as problems to be faced by driverless cars. The reason that the trolley problems exists in so many different forms, and the fact that it continues to be debated, shows that this is not a problem that we have moved on from. You would also have to be highly optimistic in your assessment of the average driver to think that a decision such as “am I more valuable than that evil man standing on the road” is going through anyone’s head; instead, people jam on the brakes. We are holding driverless cars to a higher standard than we accept for driving when it’s humans. We posit ‘difficult problems’ that we apparently ignore every time we drive in the rain because, if we did not, none of us would drive!
Humans are capable of complex ethical reasoning. This does not mean that they employ it successfully in the 1.5 seconds of reaction time before slamming on the brakes.
We are not being fair in this assessment. This does not diminish the value of machine ethics debate but it is misleading to focus on it here as if it really matters to the long term impact of driverless cars. Truck crashes are increasing in number in the US, with over 100,000 people injured each year, and over 4,000 killed. Trucks follow established routes. They don’t go off-road. This makes them easier to bring into an automated model, even with current technology. They travel long distances and the fatigue and inattention effects upon human drivers kill people. Automating truck fleets will save over a million lives in the US alone in the first decade, reducing fleet costs due to insurance payouts, lost time, and all of those things.
We have a long way to go before we have the kind of vehicles that can replace what we have but let’s focus on what is important. Getting a reliable sensory rig that works better than a human and can brake faster is the immediate point at which any form of adoption will start saving lives. Then costs come down. Then adoption goes up. Then millions of people live happier lives because they weren’t killed or maimed by cars. That’s being fair. That’s being honest. That will lead to good.
Your driverless car doesn’t need to be prepared to kill you in order to save lives.