1. The Trolley

I am using ‘Trolley Problem moral philosophy’ as a shorthand for philosophy that relies on stylized examples involving choices whether to save or kill different numbers of individuals. It has become a philosophical phenomenon, with at least two recent popular books exploring the questions, and routine mentions in the news.Footnote ¹ The core of the problem is explaining why, if it is all right for someone to divert a runaway trolley car from a track where it will roll over and kill five persons, to a different track where it will kill only one, it is nonetheless wrong for a surgeon who can save five people dying of organ failure to do so by killing and harvesting the organs of a healthy person in for a checkup. Philosophers then ring variations on these themes, for instance stopping the train by pushing someone else onto the tracks or having a bystander rather than a driver pull the switch, with the aim of extracting general principles that regulate when threats can be diverted, even at the cost of others’ lives.

As James Wilson (Reference Wilson2020) has recently argued, Trolley Problems, in their spurious clarity, precision, and narrow range of possible choices, are unlike actual complex ethical decisions which, when properly deliberated, involve nuanced judgments about framing, imaginative consideration of alternatives, and open discussion of how to balance only partially commensurable values. What they do not involve, in actual practice or (according to Wilson) in philosophical reconstruction, is confident, intuitive declaration of binary (right/wrong) principles (Wilson, Reference Wilson2020). Few ethical choices, even in medicine, involve balancing individual life against life; the hardest problems of ethics (and politics) involve questions of trust, well-being, and privacy, and invoke qualities like integrity, kindness, and fairness. Even where lives are at stake, for instance in funding health care, or safety regulation, decisions involve enormous uncertainties amid statistical judgments of mortality in populations – not a split-second decision to throw a switch. I agree wholeheartedly with Wilson’s critiques, but here I focus on a different dimension of Trolley ethics: its radical individualism, culminating in the authorization of killing civilians in drone warfare.

Trolleyology originated almost half a century ago in the context of a political battle that is still very much ongoing: the battle over the right to abortion. The first use of the example is in Phillipa Foot’s Reference Foot1967 article, ‘The Problem of Abortion and the Doctrine of Double Effect’, where Foot laid out the case for the morality of some forms of abortion by starting with the strongest anti-abortion premise, that a foetus be deemed to have the same rights as an adult, and then considering under what conditions it might still be permissible to cause the foetus’s death in order to save the mother’s life (a problem in canon law) (Foot, Reference Foot1967). Hence Foot’s reliance on examples that put various adult lives in conflict. She argues that, in general, while we can choose to kill fewer people rather than more when we must kill either way, we cannot choose to kill to prevent even more deaths: a surgeon cannot harvest organs from a healthy patient even to save the lives of five others. Applied to abortion, her conclusion is surprisingly conservative: she largely agrees with Catholic teaching that a doctor may not generally destroy a foetus to save the mother. The only exceptions are when both would otherwise die, or when the only alternative is killing the mother to save the foetus, where doctors may choose whose death they cause.Footnote ² Foot argues that the best explanation of our shared aversion to killing in her examples is by distinguishing between stronger ‘negative’ duties not to interfere with someone’s life or other interests, versus ‘positive’ duties to affirmatively help them, corresponding to rights to be helped that are less stringent than rights not to be harmed.

Foot’s reformulation of the problem in terms of individual rights led to the next stop in Trolley history: Judith Jarvis Thomson’s (Reference Thomson1971) ‘A Defense of Abortion,’ in the inaugural issue of Philosophy & Public Affairs. Thomson, who would go on to author three canonical treatments of the Trolley problem itself (and to give it its name) here resorts to a different and perhaps even more outlandish example: you wake up to discover yourself connected to a concert violinist, who needs for some reason to live off your kidney for the next nine months. Thomson argues that you would be within your rights to deny this parasitical violinist access to your kidneys, thereby causing his death. To spell out the analogy to abortion, Thomson therefore thinks that it is permissible to cause the death of a foetus, in circumstances in which you bear no responsibility for its attachment to you, as in cases of rape; she therefore modestly rebuts extreme anti-abortion positions which would prohibit even those abortions.Footnote ³

What leaps out to contemporary eyes is how Thomson ignores the broader context of pregnancy and abortion – how they bear upon questions of social and economic equality – so reducing the issue to a question of individual rights. Detaching the parasitic violinist becomes a form of self-defence, grounded in the host’s right to an autonomous existence, even against someone who is not at all responsible for the threat they pose. She makes the right to abortion look like a right not to provide lifesaving aid to an adult. It is, in fact, a position of extreme political libertarianism, which begins with the question of how to protect ourselves against the claims of others, rather than the question of what we owe to each other. The abstract, ostensibly neutral framing of the violinist example pictures a world of autonomous adults, one of whom comes to be arbitrarily attached to another. The intuitions the example generates are effects (or symptoms) of that very specific, if irreal, political conception, not a basis for it. Thus, the extreme modesty of the abortion positions Foot and Thomson defend should be no surprise, because they are consistent with an imagined political landscape that makes no room for women as political, as well as moral, subjects. An account of abortion that abstracts from pregnancy, childbirth and parenthood, or the specifics of women’s lives and the ways their choices are shaped by others, is bound to be reactionary, even if it provides an argument against the most extreme forms of forced childbearing.Footnote ⁴

Foot at least does not place great weight on her examples, skipping from one to the next as illustrations of a broader principles. Thomson, by contrast, pioneers treating examples as objects of profundity, from which general lessons may be extracted. Her later work shows her changing her mind about these lessons, as she frames and re-frames the problem, especially as she builds out complex narratives based on Foot’s skeletal trolley scenario.Footnote ⁵ Even though Thomson’s judgements rest explicitly on the details of her examples – for instance, whether the individuals on the tracks assumed the risk of accidents when they took jobs or hopped fences, the specifics of track geometry, particular kinetic mechanisms for slowing trains – she claims to be discerning generally applicable principles of moral decision-making from these investigations. Thomson ultimately concludes that in fact neither bystanders at the switch nor surgeons can cause a death to save more lives – and so, since there is no inconsistency, there is no ‘Trolley problem’. She argues that since no one can be obligated to sacrifice themselves to save strangers, it would be wrong for someone to impose that burden on a third party (Thomson, Reference Thomson2008).

But outside the pages of philosophy journals, few would contest the principle generally prohibiting taking innocent lives to save others, which is embedded in social practice, laws, and institutional regulations.Footnote ⁶ The real import of Thomson’s Trolleyology is her presumption that we find moral truth by eliminating the social context that gives our judgments their footing.

2. Trolley Libertarianism

The radical libertarianism of trolley morality becomes clear in the work of Robert Nozick. His Anarchy, State and Utopia is a touchstone for economic libertarians, who admired it for its argument against redistributive taxation (Nozick, Reference Nozick1974). The work has become at least as influential in discussion of rights to self-defence. Nozick invents two examples to argue that individuals may defend themselves with lethal force against ‘innocent aggressors’ (non-culpable threats) and at the cost of the lives of ‘innocent shields’ (passive third parties who will be harmed by the self-defence). In the trolley tradition of outlandish examples, he makes his case with examples of persons thrown down wells, whom you (at the bottom of the well) may vaporize with your ‘ray gun,’ and others strapped to the front of tanks attacking you (Nozick, Reference Nozick1974, p. 35). The examples force an urgent choice: between them and me, may I save myself?

Scenarios involving ray gunners in wells support Nozick’s central example of a ‘Wilt Chamberlain’ who gets rich through fans voluntarily paying a fee to see him play (Nozick, Reference Nozick1974, pp. 160–161). This example is the mainstay of his argument against redistributive taxation, on the grounds that a tax system would require a ‘continual interference’ with the lives of the would-be spectators by preventing them from paying to watch Will play. Nozick’s argument that social interests can’t justify interfering with financial transactions is a much more straightforwardly libertarian position than Thomson’s, whose analogies don’t easily extend from trolley crashes to taxation. Like the ray-gunner, anti-tax Wilts don’t need to regret the needs of others they chose not to meet by standing on their rights. But it rests on the same flaws of the genre: it relies on a narrowly constructed context for its positive thesis (basketball as harmless amusement, Wilt’s reputation and skill), contrasts it with the ‘harm’ of taxation, and ignores important background considerations that might lead to contrary conclusions (the economy that provides spectators with their incomes; the political and social costs of wealth inequality; the automatic, background character of modern tax systems). The trick for moral argument by example is to load into the example all and only the normative features that favour the conclusion you want to reach, thus begging the question.

3. Scientism in Moral Philosophy

Since morality is not just socially embedded but the fabric of social life itself, you might wonder why philosophers interested in the subject would find these deracinated examples credible as a way of discovering fundamental moral truths. In Nozick’s case, the impulse to derive general political consequences from abstract examples is deliberately ideological, in the narrow sense. But there is a more general explanation for Trolleyology’s siren appeal to even those who don’t pursue a libertarian political vision. That explanation comes from looking at another aspect of trolleyology: its scientism. By ‘scientism’ I mean a strategy of argument that mimics the procedures of science as a way of achieving intellectual respectability. I am not the first to call twentieth century Anglo-American philosophy ‘scientistic’.Footnote ⁷ Scientism involves a specific kind of professionalization, including overuse of formal notation, a claim to ahistorical objectivity, and the proliferation of technical jargon, all of which serve as effective barriers against the rest of the humanities, and perhaps as routes to the financing enjoyed by the sciences. It is also scientistic to suggest that we can discover moral truths through an experimental, rather than discursive, method, even if that method’s location is in the mind. Gedankenexperiments have a long and distinguished history in actual physical science, to be sure, where they are useful ways to illuminate implications or contradictions flowing from hypothesized principles. But trolleyology stands this model on its head, treating the thought experiment as the source, rather than testing ground, for the principles themselves.

The idea of using trolley examples as experiments seems especially suspect since the same examples produce different intuitions in different people, and in the same people over time. Attempts by explicitly ‘Experimental philosophers (X-phi)’, notably Joshua Knobe and Shaun Nichols, attempted to correct for this problem by running surveys, then, essentially, counting heads to suss out operative ethical principle (Knobe & Nichols, Reference Knobe, Nichols, Knobe and Nichols2008). But it is hard to see why anything short of a univocal response should give rise to any conclusions about moral principles. Moreover, the fact that the ‘experimenter’ can slightly alter the framing of the example and change judgments should be a warning about the method.

Oddly, however, neither Thomson nor her chief successor in trolley problems, Frances Kamm, seems to have worried about inconsistent intuitions. Thomson says her personal judgements ‘serve as data for the theory of rights to be presented’ (Thomson, Reference Thomson1990, p. 4). Kamm gives a more elaborate account of the example-based method, treating it like a biologist encountering a strange new organism ‘Consider as many case-based judgments of yours as prove necessary… . Be prepared to be surprised at what this principle [you discover] is’ (Kamm, Reference Kamm2007, p. 5). Discussion by example can enhance a reader’s understanding. But as scientific method, it is hardly credible: the method is completely solipsistic despite its empirical claims and depends on the validating judgements of theorists trying to prove their own theses. The idea that each of us has independent moral value is far from needing a defence by way of exotic example; the question is the limits of the idea, which contested examples cannot resolve.

The scientism of Trolleyology reaches its apogee in the work of John Mikhail, a philosopher/psychologist/lawyer, who has set out to show that patterns of moral judgment are universal, and that he can explain these patterns by a moral analogue to the innate grammar faculty posited by Noam Chomsky to explain how virtually any baby can come to understand and speak any human language (Mikhail, Reference Mikhail2011).Footnote ⁸ For Mikhail, just as a native speaker of English can identify even the nonsense phrase ‘Colorless green ideas sleep furiously’ (in Chomsky’s famous example) as a grammatically correct sentence, so too can any person decide when and where someone may divert a rampaging trolley, without any knowledge of trolleys, law or moral philosophy. In Mikhail’s view, we are all ‘intuitive lawyers’, capable of assigning responsibility in novel situations despite complex trade-offs and causal structures (Mikhail, Reference Mikhail2011, Ch. 5.4). He claims to demonstrate this universal lawyerly intuition by means of global opinion surveys. While Mikhail adds a form of empiricism to the solipsistic intuition mongering of the original trolleyologists, it remains hard to see how these majoritarian principles can be separated from the imagined political contexts that shape them. Moreover, as Thomas Nagel argued against Rawls’ original suggestion of the linguistic analogy, while ordinary speakers’ views are decisive about grammar, conventional views about morality are anything but decisive (Nagel, Reference Nagel1973).Footnote ⁹

But the project quickly founders. Except for the two familiar, widely-agreed poles of Trolleyology – pace Thomson, that a bystander can divert the train onto one to save five, but that no one should stop it by throwing a bystander under its wheels – most of the responses to surveys about trolley cases indicate widespread ambivalence, not universal agreement, with only small majorities (4–18%) favouring one choice over the other (Mikhail, Reference Mikhail2007). Given the range of responses, there is a simpler explanation than a complex universal moral faculty: we share basic values of both preferring less harm to more and avoiding being oneself the direct source of harm to others. These two values hardly amount to a basic faculty of moral judgment; balancing them is the trick in almost any relevant circumstance.

Trolleyology’s mistake is reduction: the illusion that the surface level complexity of some phenomenon masks a deeper simplicity, an atomic vocabulary of rights, intentions, and causes. This is another aspect of scientism: the drive to reduce complexity to a much smaller set of fundamental principles. Reductions may be possible in some areas of science, where complex phenomena might be explained by the lawlike behaviour of some set of simpler properties.Footnote ¹⁰ But there is no reason to think that reduction is possible in ethics or politics. Even if we could plug standardized descriptions into a moral calculator and receive specific instructions, we would still know nothing more about what we should do, only what a computer running these rules would do, because our choices, unlike a computer’s, are made in awareness of context and relationships. A mechanical system making trolley-type choices would be frightening because it wouldn’t be making moral choices at all. It would be like trying to understand a landscape from topographical lines alone.

4. From Imaginary Trolleys to Real Drones

Fortunately, there are not yet any automatic systems in civilian life implementing the results of trolley problem surveys.Footnote ¹¹ However, one context might seem to lend itself to trolley-type examples: military decisions about how to balance deaths of soldiers and civilians in pursuit of military advantage. Churchill’s order to the Calais garrison to fight to the death or compelled surrender is perhaps the most famous example of a pure kill-some-to-save-more decision. If Nozick used Trolleyology to argue against taxation and social welfare, thus in favour of letting people starve or die of penury, some more recent uses of trolleyology go a step further, authorizing killing civilians outright in the context of war. Both are the paradoxical results of an abstract theory of individual, inviolable, rights.

America’s Iraq and Afghanistan wars stimulated a wave of work among moral philosophers in so-called ‘Just War theory’, which attempts to determine when states can go to war and what means they can use.Footnote ¹² The traditional Just War view (which does not make use of Trolleyology at all) is heavily state-centered: only states have a right to use military force, and only when their territories or peoples are threatened. Individual soldiers have a right to use force so long as they are ordered to fight by their states, whether or not their state is itself justified in going to war: German soldiers invading France had as much right to fight as Polish defenders, in the sense that they are punishable only for violating the laws of war (by, say, torturing or executing prisoners) and not for fighting itself. This principle is known as the symmetry of combatants.

The Just War tradition also distinguishes sharply between combatants whom the military can target deliberately, and non-combatants whom soldiers cannot attack directly; this is called the principle of distinction. Soldiers may still knowingly kill non-combatants as long as they don’t directly intend their deaths, but they are a necessary and proportional effect of a justified attack on a legitimate target. This is the license for ‘collateral damage,’ and reflects a specific version of the Doctrine of Double Effect. The distinction between combatants and non-combatants is mainly a matter of status: soldiers can target and kill enemy combatants even when they are not carrying weapons or presenting a threat, and even if they are coerced draftees, while soldiers must protect civilians, even if they are working in war factories, or voting for and paying taxes to militarist governments.Footnote ¹³

These fundamental principles may appear incoherent, for instance because they protect the politicians who order wars while making vulnerable the draftees who fight them. And even if these rules were strictly observed, they would permit a great deal of killing of combatants and non-combatants alike. But the alternative to these principles is usually thought to be no principles – the kind of total war that characterized Sherman’s march across the South in the Civil War, or aerial bombing practices by Axis and Allies alike in World War II, which left twice as many civilians dead as soldiers.

In the last two decades, a group of philosophers influenced by Thomson and Nozick have tried to use their approach to challenge the traditional Just War principles. These self-labelled ‘revisionists’ propose to look at the problem of war through the atomistic lens of individual morality instead of the collective, state-based lens.Footnote ¹⁴ Since ordinary morality, mainly concerned with promise-keeping, lying, and duties to help strangers, etc., has had little in to say about killing except for an injunction not to do it, the only conceptual resources available to these revisionists were moralized versions of Anglo-American laws of individual self-defence, and the killing/letting die trolley dilemmas.

In doing so, they have pursued their analysis without relying on the idea of a state. Their working hypothesis is that they can analyse large-scale conflict into a web of individual acts of attack and defence, some justified, some unjustified. War, on the picture that emerges from revisionist just war theory, looks like a larger version of a liquor store armed robbery gone wrong. Morally, only the victims and responding police have a right to use force; even if the robbers fire back at the police in self-defence, they will do so unjustly. In the language of the revisionists, the robbers are ‘liable’ to be killed: people who kill them do no wrong.

One can be sceptical of the wisdom of the traditional ethics of war, especially in relation to its broad permissiveness towards mass violence.Footnote ¹⁵ Traditional war ethics reflect a range of both humanitarian concerns and the interests of powerful state actors. But at least the tradition takes war seriously as a collective, political endeavour. The revisionist approach, by contrast, in reducing war to individual conflict, founds itself in moral ‘intuitions’ that are rooted in specific and contingent legal systems of criminal self-defence, which themselves presuppose a general scheme of state authority and background institutions for resolving conflicts. This repeats the original sin of Trolleyology in the abortion context where it arose: it pretends that its abstract individualism is simply an aspect of a morally and politically neutral method, when in fact the whole system is cooked to avoid judgements about collective processes and responsibilities.Footnote ¹⁶

A surprising consequence of this pernicious individualism is that in the context of war, trolley-thinking can expand, rather than contract, the permission to kill. The examples revisionists rely on are clearly rigged from the start, the conclusions built into the descriptions. Theorists draw principles from examples of people pushing each other off bridges into ponds, ray-gunners and unwilling tank-protectors, robbers and dark alleys. The causal role that individuals will play in deadly outcomes is assigned by the writer, and all relevant information is known in advance. You, innocent of any threat, are asked how you would weigh your life (or arm, etc.) against someone who will hurt or kill you if you do nothing. Whether the threat you face is from unconscious drivers or draftee soldiers, you arrive at a clear conclusion: if only one of us can survive, it’ll be me.

The next step extends the examples to indirect threats, for instance an ambulance driver helping a potential murderer, a farmer whose crops feed soldiers. In the forced, binary choice of which of us should die if one must, again only one answer is plausible: the person who ‘contributes’ to a threat. And so these revisionists endorse the potential killing of Red Cross workers who, aiding just and unjust combatants alike, will unintentionally make further unjustified attacks likelier; or taxpayers, whose taxes support the army.Footnote ¹⁷ Once we can identify someone’s causal support for the threat facing me, it doesn’t matter whether it comes in the form of a trigger finger, a vote for a militarist candidate, or money for matériel. The forced choice between you and the ‘contributor’ transforms the reasonable judgment that civilians in states fighting unjust wars bear some more moral responsibility, to the much harsher judgment that they thereby deserve to die. Since all states regard themselves as justified when they go to war, and since most adults in an integrated economy contribute in some sense to all state actions, the upshot of such arguments is a moral green light to attack civilians. Some revisionists do resist this conclusion, on the grounds that such indirect contributors do not make a sufficient difference to warrant liability (Lazar, Reference Lazar2010). Others emphasize that they are merely alerting us to moral complexity, but that it would be unwise to disturb existing conventions for that reason (McMahan, Reference McMahan, Shue and Rodin2008).

The reductive approach to war fails by ignoring the social and political context in which wars are conceived, fought, and resolved, including the deeply-rooted distinction between soldiers and civilians, the effects of propaganda and informal coercion on civilians, the essential long-term value of reciprocal restraint, and the way in which seeing whole populations as deadly enemies jeopardizes any future possibility of peace.Footnote ¹⁸ We should also notice that the popularity of a reductive, computable, hyper-individualized ethics of war coincides with the modern military practice of powerful states. No wonder Trolleyology has become a required subject of study at West Point.Footnote ¹⁹ These are the endless contemporary wars of targeted kill squads and drone strikes, which claim to find moral vindication in their reduction of war to individual retributive justice.

The artificial picture of trolley ethics gives rise to the illusion of the morally costless war. Look at the recent, tragic drone killing by the US of ten Afghans, seven of them children, erroneously thought to be linked to a terrorist threat, but who in fact were relief workers and their families. Such killings happen because generals promise that war can be waged ‘over the horizon’ and that they can make morally just decisions to kill with gods-eye certainties about who is ‘liable to be killed,’ regardless of uniforms, and how the numbers of targetable v. non-targetable dead balance out.Footnote ²⁰ Defenders of drone programs insist that they are better than the alternative, ground forces whose record of deliberate and accidental killing will be far worse.Footnote ²¹ But these arguments fail to note that drone strikes rarely take the place of military occupations. They instead supplant diplomacy, the development of internal political capacities, and decisions to harden defences rather than to attack pre-emptively. The dream is a computable ethics, reducing problems of life, death, and politics to a universal calculus. But the dream itself is mad, for ethics does not detach from life in these forms, and ethical choice will always be as messy as the contexts in which it arises. The result of reduction is the nullification of moral philosophy to the point where it authorizes anything and everything: go ahead, kill them all.

Ethics is not science. It is a difficult conversation, filled in by many voices, some in chorus and some in dissent. Resolving what to do about the daunting problems confronting us, from climate change to equal justice to undoing the wrongs of an enslaving and colonial past, cannot be reckoned by facile distinctions between negative and positive duties, or direct or indirect causation, or intention. The forum for that conversation is our collective life, and we must anchor philosophy in history, politics, and literature. A humanistic engagement in these questions offers no guarantees for a more decent world, but at least we will not hide from moral complexity; at least we will not be evacuating all content from moral philosophy until it is good only for authorizing unlimited violence.Footnote ²²