Holding the manufacturers responsible for any crash caused by the vehicle would probably be the most obvious solution. They are, after all “ultimately responsible for the final product” (Marchant and Lindor 2012): the vehicle including the system guiding it. If there is some flaw (or some design decision)Footnote 2 in the system, which tends to cause accidents in certain situations, they probably knew or should have known about it but sold the defective autonomous cars anyway. Why should they not have to take responsibility?

The clearest answer is a practical one: if in the case of crashes involving autonomous vehicles the main responsibility were to be that of the manufacturers, “the liability burden on the manufacturer may be prohibitive of further development.” (Marchant and Lindor 2012) Of course, full legislative protection from liability would probably also have undesirable effects: “it diminishes, if not eliminates, the incentives for manufacturers to make marginal improvements in the safety of their products in order to prevent liability.” (Marchant and Lindor 2012) Could a partial liability be designed in such a way that the continuous development and improvement of autonomous vehicles would not be impeded but promoted? It seems likely, but this question would have to be discussed and answered elsewhere. An ethical analysis would not solve it.

There is, on the other hand, the question of whether we should try to promote the development of autonomous cars to begin with. In other words: should we try to design the liability for autonomous vehicles in such a way that it promotes their continuous development and improvement? Should such vehicles be allowed on our streets? These questions can be addressed through normative ethics. If there are good moral reasons for finding the development and introduction of autonomous cars to be desirable, this can produce a moral obligation for the state to fashion the legal responsibility for crashes of autonomous cars in a way which helps the development and improvement of autonomous cars.

There are many arguments which can be made in favour of or against the introduction of autonomous cars. Possible problems include privacy issues (Glancy 2012) and environmental harm from fully-autonomous vehicles, as these could lead to more vehicle-miles travelled (Elkind 2012). On the positive side, the introduction of autonomous cars might among other things enable the physically impaired, disabled or elderly to drive their own vehicles (Howard 2013). However, a thorough discussion of these additional issues would exceed the scope of this article.

We will therefore focus on one possible reason in favour of autonomous cars which (at least potentially) could be of tremendous moral weight: The development and widespread use of autonomous cars could cause a reduction of accidents, it could therefore save lives.Footnote 3 Even if we are talking of a relatively small improvement like a reduction of 5 % it would save hundreds of lives a year in countries like the US in which deaths in road accidents go into the tens-of-thousands. This by itself seems like a powerful prima-facie reason to promote the development of autonomous cars (we would and should probably not be willing to sacrifice hundreds of people to improve the privacy of car-users or to avoid an increase of miles driven per year). But is it? There might be reasons to have doubts about the moral status of these saved lives:

“Let’s say that autonomous cars slash overall traffic-fatality rates by half. So instead of 32,000 drivers, passengers, and pedestrians killed every year, robotic vehicles save 16,000 lives per year and prevent many more injuries. But here’s the thing. Those 16,000 lives are unlikely to all be the same ones lost in an alternate world without robot cars. When we say autonomous cars can slash fatality rates by half, we really mean that they can save a net total of 16,000 lives a year: for example, saving 20,000 people but still being implicated in 4,000 new deaths. There’s something troubling about that, as is usually the case when there’s a sacrifice or “trading” of lives. The identities of many (future) fatality victims would change with the introduction of autonomous cars. Some victims could still die either way, depending on the scenario and how well robotic cars actually outperform human drivers. But changing the circumstances and timing of traffic conditions will likely affect which accidents occur and therefore who is hurt or killed. […] some current non-victims—people who already exist—would become future victims, and this is clearly bad.” (Lin 2013).

This objection, if it proved true, could be very powerful: The central function of a democratic, liberal state is to safeguard individual rights and liberties. Its central norms should not be consequentialist but deontological in nature and the interpretation of these norms is categorical, not hypothetical. A violation of some person’s fundamental rights cannot be legitimized on the basis of benefits for others, no matter how large. The normative order of a democracy should recognize individual rights, and the right to live protects every single individual against state decisions which might threaten them. To protect these fundamental individual rights is a goal of the state which should override any other. Other goals, including the interests of the majority, cannot be weighed against them. Of course, additional normative factors such as well-being or equality also play an important role. Nevertheless, the deontological character of a liberal democracy’s normative order manifests itself partly in preventing trade-offs when it comes to certain individual rights and liberties. The minimisation of collective risks therefore often comes into conflict with this constitutive element of any humane order and specifically of liberal democracies.Footnote 4

However, is it plausible to make out a conflict of that kind in our case? Would the introduction of autonomous vehicles really sacrifice the interests of one group to safeguard the interests of the majority? The introduction of autonomous vehicles is quite different from the paradigm of trolley-cases.Footnote 5 In contrast to the standard trolley-case, we should not focus on the actual damage done in the end, when we try to determine if a decision in favour of autonomous vehicles is in the interest of one of the affected parties. Instead, the risks at the time of the decision should become central. Whether or not the introduction of a new safety feature is in the interest of a person does not depend on whether or not the person in question does have an accident in the end or how bad it may come to be. It depends on whether the feature improves his chances of avoiding the accident or reduce possible damage. If an action is in the interest of a person, this is true irrespectively of what its consequences are. Let’s say he had to travel from Egypt to South Africa and it were rational to expect one form of traveling (e.g., using airplanes) to be significantly safer than another (e.g., going by boat). Assuming he were correspondingly advised by his friend to use the plane; this action remains prudent even if it turns out that the airplane crashes and his colleague, who took a boat, had a perfectly safe and pleasant journey. It remains prudent under the condition that his expectation was rational or that it was rational to follow the advice of the more experienced or better-informed friend. Even a very low probability that some event might occur is compatible with the fact that this event did in fact take place. The prudential choice has maximal expected value regarding the interest of the person in question. A decision is prudential if and only if its expected value with regard to a person’s personal interests is maximal at the time the decision is made, whatever its eventual consequences. Therefore, we judge an action to be in the interest of a person given the probabilities and given the preferential situation at the moment the decision takes place. It is a fallacy to take the real consequences of a decision into account when confronted with probabilistic phenomena. What counts when we decide if a possible action is in the interest of a person is the probability of that decision’s consequence, not the actual consequence itself.

The non-identity problem that Lin refers to in the above quotation is therefore only applicable to autonomous cars if there is an identifiable group of individuals whose risks might be increased by the introduction of autonomous cars. If that proves to be the case, it would certainly pose a problem. Otherwise, Lin’s concerns are unfounded.Footnote 6 The introduction of autonomous cars would be no different (in this regard) to the introduction of already well-established safety features such as seatbelts or glued-in laminated windshields. There might be cases in which any of these safety features do more harm than good. A modern, glued-in windshield might, for example, delay rescue for a few critical moments, causing an accident victim to bleed to death. However, these tragic cases do not change the fact that having these features significantly improves the overall safety of those who use cars. Having them as part of the car is therefore in the interest of the users. Moreover, this is also true for those unlucky few who end up hurt because of them. The objection that the introduction of autonomous vehicles would sacrifice a smaller group for the good of a larger one is therefore unfounded.

The consequentialist tries to reduce the diversity of morally relevant factors including duties, rights, principles etc. to one single principle: one should maximize the good. There are many reasons to reject such a reductionist scheme. (Nida-Rümelin 1995) However, a teleological rationale can still provide powerful moral reasons, especially when the good to be promoted is as important as in this case. Death and injury caused by accidents are an evil, and the protection of its citizens from such harm is a central task of the state. If the introduction of autonomous vehicles might reduce the yearly toll in death and injury exacted by road traffic even by a small degree, that would constitute a powerful moral reason in favour of promoting their development—which includes trying to design car manufacturers tort liability in such a way that the development and improvement of autonomous vehicles will be helped along. This depends, however, on there not being a group of people whose risks of injury are bound to be raised by the introduction of autonomous cars. If there was to be such a group, this could pose a major ethical problem for the introduction of autonomous cars.