Yikes - even Barack Obama wants to solve robocar "Trolley Problems" now
I had hoped I was done ranting about our obsession with what robocars will do in no-win "who do I hit?" situations, but this week, even Barack Obama in his interview with Wired opined on the issue, prompted by my friend Joi Ito from the MIT Media Lab. (The Media Lab recently ran a misleading exercise asking people to pretend they were a self-driving car deciding who to run over.)
I've written about the trouble with these problems and even proposed a solution but it seems there is still lots of need to revisit this. Let's examine why this problem is definitely not important enough to merit the attention of the President or his regulators, and how it might even make the world more dangerous.
We are completely fascinated by this problem
Almost never do I give a robocar talk without somebody asking about this. Two nights ago, I attended another speaker's talk and he got the question as his 2nd one. He looked at his watch and declared he had won a bet with himself about how quickly somebody would ask. It has become the #1 question in the mind of the public, and even Presidents.
It is not hard to understand why. Life or death issues are morbidly attractive to us, and the issue of machines making life or death decisions is doubly fascinating. It's been the subject of academic debates and fiction for decades, and now it appears to be a real question. For those who love these sorts of issues, and even those who don't, the pull is inescapable.
At the same time, even the biggest fan of these questions, stepping back a bit, would agree they are of only modest importance. They might not agree with the very low priority that I assign, but I don't think anybody feels they are anywhere close to the #1 question out there. As such we must realize we are very poor at judging the importance of these problems. So each person who has not already done so needs to look at how much importance they assign, and put an automatic discount on this. This is hard to do. We are really terrible at statistics sometimes, and dealing with probabilities of risk. We worry much more about the risks of a terrorist attack on a plane flight than we do about the drive to the airport, but that's entirely wrong. This is one of those situations, and while people are free to judge risks incorrectly, academics and regulators must not.
Academics call this the Law of triviality. A real world example is terrorism. The risk of that is very small, but we make immense efforts to prevent it and far smaller efforts to fight much larger risks.
These situations are quite rare, and we need data about how rare they are
In order to judge the importance of these risks, it would be great if we had real data. All traffic fatalities are documented in fairly good detail, as are many accidents. A worthwhile academic project would be to figure out just how frequent these incidents are. I suspect they are extremely infrequent, especially ones involving fatality. Right now fatalities happen about every 2 million hours of driving, and the majority of those are single car fatalities (with fatigue and alcohol among leading causes.) I have still yet to read a report of a fatality or serious injury that involved a driver having no escape, but the ability to choose what they hit with different choices leading to injuries for different people. I am not saying they don't exist, but first examinations suggest they are quite rare. Probably hundreds of billions of miles, if not more, between them.
Those who want to claim they are important have the duty to show that they are more common than these intuitions suggest. Frankly, I think if there were accidents where the driver made a deliberate decision to run down one person to save another, or to hurt themselves to save another, this would be a fairly big human interest news story. Our fascination with this question demands it. Just how many lives would be really saved if cars made the "right" decision about who to hit in the tiny handful of accidents where they must hit somebody?
In addition, there are two broad classes of situations. In one, the accident is the fault of another party or cause, and in the other, it is the fault of the driver making the "who to hit" decision. In the former case, the law puts no blame on you for who you hit if forced into the situation by another driver. In the latter case, we have the unusual situation that a car is somehow out of control or making a major mistake and yet still has the ability to steer to hit the "right" target.
These situations will be much rarer for robocars
Unlike humans, robocars will drive conservatively and be designed to avoid failures. For example, in the MIT study, the scenario was often a car whose brakes had failed. That won't happen to robocars -- ever. I really mean never. Robocar designs now all commonly feature two redundant braking systems, because they can't rely on a human pumping the hydraulics manually or pulling an emergency brake. In addition, every time they apply the brakes, they will be testing them, and at the first sign of any problem they will go in for repair. The same is true of the two redundant steering systems. Complete failure should be ridiculously unlikely.
The cars will not suddenly come upon a crosswalk full of people with no time to stop -- they know where the crosswalks are and they won't drive so fast as to not be able to stop for one. They will be also constantly measuring traction and road conditions to assure they don't drive too fast for the road. They won't go around blind corners at high speeds. They will have maps showing all known bottlenecks and construction zones. Ideally new construction zones will only get created after a worker has logged the zone on their mobile phone and the updates are pushed out to cars going that way, but if for some reason the workers don't do that, the first car to encounter the anomaly will make sure all other cars know.
This does not mean the cars will be perfect, but they won't be hitting people because they were reckless or had predictable mechanical failures. Their failures will be more strange, and also make it less likely the vehicle will have the ability to choose who to hit.
To be fair, robocars also introduce one other big difference. Humans can argue that they don't have time to think through what they might do in a split-second accident decision. That's why when they do hit things, we call them accidents. They clearly didn't intend the result. Robocars do have the time to think about it, and their programmers, if demanded to by the law, have the time to think about it. Trolley problems demand the car be programmed to hit something deliberately. The impact will not be an accident, even if the cause was. This puts a much higher standard on the actions of the robocar. One could even argue it's an unfair standard, which will delay deployment if we need to wait for it.
In spite of what people describe in scenarios, these cars won't leave their right of way
It is often imagined an ethical robocar might veer into the oncoming lane or onto the sidewalk to hit a lesser target instead of a more vulnerable one in its path. That's not impossible, but it's pretty unlikely. For one, that's super-duper illegal. I don't see a company, unless forced to do so, programming a car to ever deliberately leave its right of way in order to hit somebody. It doesn't matter if you save 3 school buses full of kids, deliberately killing anybody standing on the sidewalk sounds like a company-ruining move.
For one thing, developers just won't put that much energy into making their car drive well on the sidewalk or in oncoming traffic. They should not put their energies there! This means the cars will not be well tested or designed when doing this. Humans are general thinkers, we can handle driving on the grass even though we have had little practice. Robots don't quite work that way, even ones designed with machine learning.
This limits most of the situations to ones where you have a choice of targets within your right-of-way. And changing lanes is always more risky than staying in your lane, especially if there is something else in the lane you want to change to. Swerving if the other lane is clear makes sense, but swerving into an occupied lane is once again something that is going to be uncharted territory for the car.
By and large the law already has an answer
The vehicle code is quite detailed about who has right-of-way. In almost every accident, somebody didn't have it and is the one at fault under the law. The first instinct for most programmers will be to have their car follow the law and stick to their ROW. To deliberately leave your ROW is a very risky move as outlined above. You might get criticized for running over jaywalkers when you could have veered onto the sidewalk, but the former won't be punished by the law and the latter can be. If people don't like the law, they should change the law.
The lesson of the Trolley problem is "you probably should not try to solve trolley problems."
Ethicists point out correctly that Trolley problems may be academic exercises, but are worth investigating for what they teach. That's true in the classroom. But look at what they teach! From a pure "save the most people" utilitarian standpoint, the answer is easy -- switch the car onto the track to kill one in order to save 5. But most people don't pick that answer, particularly in the "big man" version where you can push a big man standing with you on a bridge onto the tracks to stop the trolley and save the 5. The problem teaches us we feel much better about leaving things as they are than in overtly deciding to kill a bystander. What the academic exercise teaches us is that in the real world, we should not foist this problem on the developers.
If it's rare and a no-win situation, do you have to solve it?
Trolley problems are philosophy class exercises to help academics discuss ethical and moral problems. They aren't guides to real life. In the classic "trolley problem" we forget that none of it happens unless a truly evil person has tied people to a railway track. In reality, many would argue that the actors in a trolley problem are absolved of moral responsibility because the true blame is on the setting and its architect, not them. In philosophy class, we can still debate which situation is more or less moral, but they are all evil. These are "no win" situations, and in fact one of the purposes of the problems is they often describe situations where there is no clear right answer. All answers are wrong, and people disagree about which is most wrong.
If a situation is rare, and it takes effort to figure out which is the less wrong answer, and things will still be wrong after you do this even if you do it well, does it make sense to demand an answer at all? To individuals involved, yes, but not to society. The hard truth is that with 1.2 million auto fatalities a year -- a number we all want to see go down greatly -- it doesn't matter that much to society whether, in a scenario that happens once every few years, you kill 2 people or 3 while arguing which choice was more moral. That's because answering the question, and implementing the answer, have a cost.
Every life matters, but we regularly make decisions like this. We find things that are bad and rare, and we decide that below a certain risk threshold, we will not try to solve them unless the cost is truly zero. And here the cost is very far from zero. Because these are no-win situations and each choice is wrong, each choice comes with risk. You may work hard to pick the "right" choice and end up having others declare it wrong -- all to make a very tiny improvement in safety.
At a minimum each solution will involve thought and programming, as well as emotional strain for those involved. It will involve legal review and in the new regulations, certification processes and documentation. All things that go into the decision must be recorded and justified. All of this is untrod legal ground making it even harder. In addition, no real scenario with match hypothetical situations exactly, so the software must apply to a range of situations and still do the intended thing (let alone the right thing) as the situation varies. This is not minor.
Nobody wants to solve it
In spite of the fascination these problems hold, coming up with "solutions" to these no-win situations are the last things developers want to do. In articles about these problems, we almost always see the statement, "Who should decide who the car will hit?" The answer is nobody wants to decide. The answer is almost surely wrong in the view of some. Nobody is going to get much satisfaction or any kudos for doing a good job, whatever that is. Combined with the rarity of these events compared to the many other problems on the table, solving ethical issues is very, very, very low on the priority list for most teams. Because developers and vendors don't want to solve these questions and take the blame for those solutions, it makes more sense to ask policymakers to solve what needs to be solved. As Christophe von Hugo of Mercedes put it, "99% of our engineering work is to prevent these situations from happening at all."
The cost of solving may be much higher than people estimate
People grossly underestimate how hard some of these problems will be to solve. Many of the situations I have seen proposed actually demand that cars develop entirely new capabilities that they don't need except to solve these problems. In these cases, we are talking about serious cost, and delays to deployment if it is judged necessary to solve these problems. Since robocars are planned as a life-saving technology, each day of delay has serious consequences. Real people will be hurt because of these delays aimed at making a better decision in rare hypothetical situations.
Let's consider some of the things I have seen:
- Many situations involve counting the occupants of other cars, or counting pedestrians. Robocars don't otherwise have to do this, nor can they easily do it. Today it doesn't matter if there are 2 or 3 pedestrians -- the only rule is not to hit any number of pedestrians. With low resolution LIDAR or radar, such counts are very difficult. Counts inside vehicles are even harder.
- One scenario considers evaluating motorcyclists based on whether they are wearing helmets. I think this one is ridiculous, but if people take it seriously it is indeed serious. This is almost impossible to discern from a LIDAR image and can be challenging even with computer vision.
- Some scenarios involve driving off cliffs or onto sidewalks or otherwise off the road. Most cars make heavy use of maps to drive, but they have no reason to make maps of off-road areas at the level of detail that goes into the roads.
- More extreme scenarios compare things like children vs. adults, or school-buses vs. regular ones. Today's robocars have no reason to tell these apart. And how do you tell a dwarf adult from a child? Full handling of these moral valuations requires human level perception in some cases.
- Some suggestions have asked cars to compare levels of injury. Cars might be asked to judge the difference between a fatal impact and one that just breaks a leg.
These are just a few examples. A large fraction of the hypothetical situations I have seen demand some capability of the cars that they don't have or don't need to have just to drive safely.
The problem of course is there are those who say that one must not put cars on the road until the ethical dilemmas have been addressed. Not everybody says this but it's a very common sentiment, and now the new regulations demand at least some evaluation of it. No matter how much the regulations might claim they are voluntary, this is a false claim, and not just because some states are already talking about making them more mandatory.
Once a duty of care has been suggested, especially by the government, you ignore it at your peril. Once you know the government -- all the way to the President -- wants you to solve something, then you must be afraid you will be asked "why didn't you solve that one?" You have to come up with an answer to that, even with voluntary compliance.
The math on this is worth understanding. Robocars will be deployed slowly into society but that doesn't matter for this calculation. If robocars are rare, they can prevent only a smaller number of accidents, but they will also encounter a correspondingly smaller number of trolley problems. What matters is how many trolley situations there are per fatality, and how many people you can save with better handling of those problems. If you get one trolley problem for every 1,000 or 10,000 fatalities, and robocars are having half the fatalities, the math very clearly says you should not accept any delay to work on these problems.
The court of public opinion
The real courts may or may not punish vendors for picking the wrong solution (or the default solution of staying in your lane) in no-win situations. Chances are there will be a greater fear of the court of public opinion. There is reason to fear the public would not react well if a vehicle could have made an obviously better outcome, particularly if the bad outcome involves children or highly vulnerable road users vs. adults and at-fault or protected road users.
Because of this I think that many companies will still try to solve some of these problems even if the law puts no duty on them. Those companies can evaluate the risk on their own and decide how best to mitigate it. That should be their decision.
For a long time, many people felt any robocar fatality would cause uproar in the public eye. To everybody's surprise, the first Tesla autopilot deaths resulted in Tesla stock rising for 2 months, even with 3 different agencies doing investigations. While the reality of the Tesla is that the drivers bear much more responsibility than a full robocar would, the public isn't very clear on that point, so the lack of reaction is astonishing. I suspect companies will discount this risk somewhat after this event.
This is a version 2 feature, not a version 1 feature
As noted, while humans make split-second "gut" decisions and we call the results accidents, robocars are much more intentional. If we demand they solve these problems, we ask something of them and their programmers that we don't ask of human drivers. We want robocars to drive more safely than humans, but we also must accept that the first robocars to be deployed will only be a little better. The goal is to start saving lives and to get better and better at it as time goes by. We must consider the ethics of making the problem even harder on day one. Robocars will be superhuman in many ways, but primarily at doing the things humans do, only better. In the future, we should demand these cars meet an even higher standard than we put on people. But not today: The dawn of this technology is the wrong time to also demand entirely new capabilities for rare situations.
Performing to the best moral standards in rare situations is not something that belongs on the feature list for the first cars. Solving trolley situations well is in the "how do we make this perfect?" problem set, not the "how do we make this great?" set. It is important to remember how the perfect can be the enemy of the good and to distinguish between the two. Yes, it means accepting there are low chance that somebody could be hurt or die, but people are already being killed, in large numbers, by the human drivers we aim to replace.
So let's solve trolley problems, but do it after we get the cars out on the road both saving lives and teaching us how to improve them further.
What about the fascination?
The over-fascination with this problem is a real thing even if the problem isn't. Studies have displayed one interesting result after surveying people: When you ask people what a car should do for the good of society, they would want it to sacrifice its passenger to save multiple pedestrians, especially children. On the other hand if you ask people if they would buy a car that did that, far fewer said yes. As long as the problem is rare, there is no actual "good of society" priority; the real "good of society" comes from getting this technology deployed and driving safely as quickly as possible. Mercedes recently announced a much simpler strategy which does what people actually want, and got criticism for it. Their strategy is reasonable -- they want to save the party they can be most sure of saving, namely the passengers. They note that they have very little reliable information on what will happen in other cars or who is in them, so they should focus not on a guess of what would save the most people, but what will surely save the people they know about.
What should we do?
I make the following concrete recommendations:
- We should do research to determine how frequent these problems are, how many have "obvious" answers and thus learn just how many fatalities and injuries might be prevented by better handling of these situations.
- We should remove all expectation on first generation vehicles that they put any effort into solving the rare ones, which may well be all of them.
- It should be made clear there is no duty of care to go to extraordinary lengths (including building new perception capabilities) to deal with sufficiently rare problems.
- Due to the public over-fascination, vendors may decide to declare their approaches to satisfy the public. Simple approaches should be encouraged, at in the early years of this technology, almost no answer should be "wrong."
- For non-rare problems, governments should set up a system where developers/vendors can ask for rulings on the right behaviour from the policymakers, and limit the duty of care to following those rulings.
- As the technology matures, and new perception abilities come online, more discussion of these questions can be warranted. This belongs in car 2.0, not car 1.0.
- More focus at all levels should go into the real everyday ethical issues of robocars, such as roads where getting around requires regularly violating the law (speeding, aggression etc.) in the way all human users already do.
- People writing about these problems should emphasize how rare they are, and when doing artificial scenarios, recount how artificial they are. Because of the public's fears and poor risk analysis, it is inappropriate to feed on those fears rather than be realistic.