The introduction to my PhD thesis

[You can read it as a PDF here.]

Population ethics is a subfield of normative ethics concerned with the distinctive issues that arise in cases where our actions can affect the identities or number of people who ever exist. Population axiology is a subfield of population ethics concerned with the value-relations that obtain between possible populations (defined as: sets of lives) where these populations likewise differ in the identities or number of people who ever exist. Population ethicists ask – and try to answer – questions like:

• In cases where all else is equal, are we morally required to create extra happy people?

• Can adding enough barely good lives to a population make that population better than any other?

• Do the interests of future generations give us additional reason to reduce the risk that humanity goes extinct in the near future?

This thesis is in population ethics. The first four chapters are in population axiology. Each chapter can be read independently of all the others. In this introduction, I provide a brief synopsis of each chapter, skating over some minor technical details. I then sketch out an argument against person-affecting views that builds on points I make in Chapter 6. I end with some comments on the appeal and importance of population ethics.

At least since the publication of Reasons and Persons in 1984, population ethicists have wrestled with what Derek Parfit called the Repugnant Conclusion: the claim that, for any population of wonderful lives, there is a better population containing only lives that are barely worth living. This conclusion is counterintuitive, but also surprisingly difficult to avoid. Parfit (1984, chap. 19) himself demonstrated that it follows from some plausible-seeming premises, and others have since done similarly (Ng 1989; Kitcher 2000; Huemer 2008; Arrhenius 2000b; 2011; Nebel 2019). Here are two premises that together imply the Repugnant Conclusion:

The Equivalence of Personal and Contributive Value

A life is personally good (that is, good for the person living it) if and only if (iff) it is contributively good (that is, good for the population of which it is a part, in the sense of contributing positively to that population’s value). Likewise, a life is personally bad iff it is contributively bad, and personally neutral iff it is contributively neutral. (see Gustafsson 2020, 87)

Archimedeanism about Populations

For any population X and any contributively good life y, there is some number m such that a population consisting of m lives equally good as y is better than X.¹

Here is why these two premises entail the Repugnant Conclusion: the Equivalence of Personal and Contributive Value implies that lives barely worth living are contributively good; Archimedeanism about Populations then implies that, for any population of wonderful lives, there is some population of lives barely worth living that is better.

Lexical views in population axiology deny Archimedeanism about Populations and so can avoid the Repugnant Conclusion. On lexical views, welfare levels – which measure how good a life is for the person living it – can be represented by vectors. Here is an example of a lexical view (Kitcher 2000; Thomas 2018; Carlson 2022; Nebel 2021). Welfare levels are represented by vectors with two dimensions. Each dimension is represented by an integer without upper or lower bound. The first dimension quantifies the higher goods in a life: perhaps things like autonomy and meaning. The second dimension quantifies the lower goods in a life: perhaps things like sensual pleasure. These vectors are ordered lexically, so that a life x with welfare level (h_x, l_x) is at least as good as a life y with welfare level (h_y, l_y) iff either h_x>h_y  or h_x= h_y  and l_x≥l_y. The value of a population X is then represented by the vector (h_X, l_X), where h_X  is the sum-total of all the higher goods in the lives in X and l_X  is the sum-total of all the lower goods in the lives in X. Populations are ordered lexically in the same way as lives, so that a population X is at least as good as a population Y iff either h_X>h_Y  or h_X=h_Y  and l_X≥l_Y.

This lexical view avoids the Repugnant Conclusion if – as can be defensibly claimed – wonderful lives feature some positive quantity of higher goods while lives barely worth living do not. And the view has many other advantages besides: it satisfies conditions like Transitivity and Separability; it can be amended to accommodate incommensurability between lives and between populations (Nebel 2021); it justifies the common preference for a century-long wonderful life over an extremely long life that is at each moment barely worth living; and all the while it remains faithful to the appealing idea that one population is at least as good as another iff it contains at least as much welfare.

Unfortunately, as I note in Chapter 1 of this thesis, lexical views imply a dilemma. The first horn we can call Strong Superiority Across Slight Differences: there exists some good life x and some slightly-worse-but-still-good life y such that a population composed of a single life x is better than any population containing only lives equally good as y, no matter how large this latter population. The second horn we can call Radical Incommensurability: there exists some good life x and some slightly-worse-but-still-good life y such that for any population containing only lives equally good as x, there is some population containing only lives equally good as y that is not worse, and yet there is no population containing only lives equally good as y that is better than a population composed of just a single life x (Handfield and Rabinowicz 2018).

We might regard the lexical dilemma as strong reason to embrace an Archimedean view in population axiology, which accepts Archimedeanism about Populations. If we also accept the Equivalence of Personal and Contributive Value, we must admit the Repugnant Conclusion, but this conclusion might seem preferable to each horn of the lexical dilemma above.

However, I argue in Chapter 1 that we should not take the lexical dilemma as strong support for an Archimedean view. That is because Archimedean views imply a similar (and similarly troubling) Archimedean dilemma. The first horn of this dilemma states that the boundary between good and bad lives is razor-sharp: an extra two hangnails’ worth of pain can flip even long and turbulent lives from contributively good to contributively bad, so that any population of lives without the hangnails is better than any population of lives with them. This horn will seem most implausible to those of us who doubt that there are such precise facts about how life’s goods trade off against life’s bads. The second horn of the Archimedean dilemma is Radical and Symmetric Incommensurability: for any arbitrarily good population and any arbitrarily bad population, there is some population that is incommensurable with both. God could create a Purgatory that is no worse than Heaven and no better than Hell. Each horn of this Archimedean dilemma is, in my estimation, about as implausible as the corresponding horn in the lexical dilemma. So, I conclude, the lexical dilemma gives us little reason to prefer an Archimedean view.

Chapter 2 also concerns lexical views, but its conclusion will not seem so welcome to advocates of those views. To see why, note first that ‘population axiology’ can refer either to the field of study or to a theory of which possible populations are at least as good as which others. It is natural to hope for a population axiology (in the latter sense) that meets certain adequacy conditions. For example, we might hope for a population axiology that implies the following: making every person’s life better in a way that ensures perfect equality is always an improvement. We might also hope to meet the following condition: there exists some number of awful lives such that, for any background population and any number of good lives, the population consisting of the good lives plus the background population is at least as good as the population consisting of the awful lives plus the background population. We might consider a population axiology satisfactory only if it meets all such intuitively compelling conditions.

Unfortunately, formulating a satisfactory population axiology has proved difficult. Indeed, some philosophers claim that it is impossible. Several philosophers offer impossibility theorems purporting to demonstrate that no population axiology can meet each of a small number of adequacy conditions (see, for example, Parfit 1984, chap. 19; Ng 1989; Kitcher 2000). Gustaf Arrhenius’s six theorems represent the state-of-the-art (2000b; 2009; 2011). They employ logically weaker and intuitively more compelling adequacy conditions than other theorems extant in the literature, and so have drawn much of the scholarly attention.

However, it has recently been pointed out that each of Arrhenius’s theorems depends on a dubious assumption: Finite Fine-Grainedness. This assumption states that there exists a finite sequence of slight welfare differences between any two welfare levels. The upshot of denying Finite Fine-Grainedness is twofold. First, it makes room for a lexical view in which welfare levels and population-values are represented by vectors. Views of this kind are a counterexample to Arrhenius’s First, Fourth, Fifth, and Sixth Impossibility Theorems. Second, it strips certain adequacy conditions of their plausibility. More precisely, it renders doubtful the Inequality Aversion condition employed in Arrhenius’s Second and Third Impossibility Theorems. Therefore, none of Arrhenius’s six theorems proves that there is no satisfactory population axiology. Each theorem depends on Finite Fine-Grainedness for the validity of its proof or the plausibility of its adequacy conditions.

Nevertheless, Arrhenius’s theorems remain important. In Chapter 2, I demonstrate that they can be turned into theorems stating the impossibility of a satisfactory population prospect axiology: a satisfactory theory of which possible population prospects are at least as good as which others, where ‘a population prospect’ is defined as a lottery over populations. These amended theorems employ risky versions of some of Arrhenius’s original adequacy conditions. Arrhenius’s original conditions mandate (roughly) that a drop in welfare for one person can be compensated by a large enough increase in welfare elsewhere. The risky versions mandate (again roughly) that a slightly increased risk of a drop in welfare for one person can be compensated by a large enough increase in welfare elsewhere. These risky adequacy conditions are compelling even if Finite Fine-Grainedness is false, so lexical views do not escape these amended theorems.

In Chapter 3, I turn my attention to critical-level and critical-range views in population axiology. On critical-level views, we first subtract some positive constant from the welfare score (that is, the real number chosen to represent the welfare level) of each life in a population and then sum the results to get the value of that population. This positive constant is the critical level. A population X is at least as good as a population Y iff the value of X is at least as great as the value of Y. On critical-range views, we calculate the value of a population on a range of critical levels. A population X is at least as good as a population Y iff the value of X is at least as great as the value of Y on every level in the critical range. If neither X nor Y is at least as good as the other, they are incommensurable. I use the term ‘critical-set views’ to refer to that class of views comprising both critical-level and critical-range views.

I offer a characterisation and taxonomy of critical-set views. I then sharpen some old objections to these views and develop some new ones. Some views imply versions of the Repugnant Conclusion; other views imply versions of the Sadistic Conclusion (Arrhenius 2000a, 256). No view can account for the incommensurability between lives and between same-size populations without extra theoretical resources.

I also formulate what I take to be the two strongest objections in the literature against critical-range views. The first objection – Maximal Greediness – builds on the work of John Broome (2004, 169–70, 202–5). I prove that critical-range views imply the following: for any population of wonderful lives and any population of awful lives, (1) there is some population of straightforwardly-better-than-blank lives (featuring no bads whatsoever and some goods) such that the population of wonderful lives plus the straightforwardly-better-than-blank lives is not better than the population of awful lives, or (2) there is some population of straightforwardly-worse-than-blank lives (featuring no goods whatsoever and some bads) such that the population of awful lives plus the straightforwardly-worse-than-blank lives is not worse than the population of wonderful lives. The second objection is that critical-range views imply discontinuities in implausible places, so that at least one of the following is true: (1) there exists some life featuring no bads whatsoever and some happiness such that a population of just that life is not worse than any population of lives identical but for a slightly shorter duration of happiness, or (2) there exists some life featuring no goods whatsoever and some suffering such that a population of just that life is not better than any population of lives identical but for a slightly shorter duration of suffering.

I then put forward what I call the Imprecise Exchange Rates (IER) View. On this view, welfare levels are represented by vectors rather than real numbers. Each component in the vector represents a quantity of some dimension of good or bad within a life. For example, one component might represent the life’s quantity of happiness, another the quantity of suffering, a third the quantity of love, a fourth the quantity of false belief, and so on. Welfare levels are compared using proto-exchange-rates: vectors with the same number of components as the vectors that represent welfare levels, with components each greater than 0 and together summing to 1.  These proto-exchange-rates denote the relative weight granted to each dimension of good and bad. Welfare levels relative to a given proto-exchange-rate can be expressed as real numbers. We obtain this real number by multiplying together each number representing the quantity of a welfare-dimension by the corresponding number in the proto-exchange rate, and then summing. A life x is at least as good as a life y relative to a proto-exchange-rate r iff the welfare level of x relative to r is at least as great as the welfare level of y relative to r. A population X is at least as good as a population Y relative to r iff the sum-total of the welfare levels of all the lives in X relative to r is at least as great as the sum-total of the welfare levels of all the lives in Y relative to r. A life x is at least as good as a life y simpliciter iff x is at least as good as y relative to each proto-exchange-rate r in the set of all admissible proto-exchange-rates. The same goes for populations. If there are multiple-proto-exchange-rates r in the set of all admissible proto-exchange-rates, it can be that neither of two lives (or two populations) is at least as good as the other, and so there we have incommensurability.

This IER View can avoid all forms of Sadistic Conclusion. It also incorporates incommensurability in a more natural way than critical-range views, allowing for incommensurability between lives and between same-number populations. And it avoids both problems mentioned above: Maximal Greediness and discontinuities in unlikely locations.

In addition, the IER View is superior to the Total View in some important respects. It does not imply that the divide between good and bad lives is everywhere razor-sharp so that two extra hangnails’ worth of pain can flip even long, turbulent lives from good to bad. The IER View also takes the edge off the Repugnant Conclusion, by raising the bar for when a life qualifies as barely worth living. To qualify, a life must feature enough goods to outweigh its bads even on the most pessimistic admissible proto-exchange-rate. Parfit’s (1986, 148) famous ‘Muzak and potatoes’ lives will come out as weakly neutral rather than barely worth living, and so the IER View will imply that no population of such lives is better than a large population of wonderful lives. The IER View thus serves as an attractive middle ground between the Total View and critical-range views.

I take the considerations that I adduce in Chapter 3 to support the IER View (and, to a lesser extent, the Total View) over critical-level and critical-range views, but the above points do not by themselves settle the issue. There are objections of the same sort on both sides, and which of the bullets to bite – Repugnance, Sadism, Greediness, etc. – is to some extent a matter of taste. I try to break the deadlock in Chapter 4 by showing that critical-level and critical-range views are vulnerable to a kind of objection to which the Total View and IER View are immune. These are objections from biographical identity: identity between lives. I argue that, if biographical identity is all-or-nothing, critical-level and critical-range views entail implausible discontinuities in the value of populations. Severing one synapse and erasing one faint memory can make a population significantly worse. If biographical identity does not require spatiotemporal continuity, then there are cases in which critical-level and critical-range views require us to become Egyptologists to determine which of our population-affecting actions is best. And if biographical identity does require spatiotemporal continuity, then critical-level and critical-range views imply some version of what I call the Blinking Sadistic Conclusion. We can add some Splitting Sadistic Conclusion to the list of charges if we subtract the critical level (or critical range) from the welfare scores of fission-products. And if we do not subtract the critical level (or critical range) from the welfare scores of fission-products, critical-level and critical-range views imply what I call the Splitting Repugnant Conclusion instead, along with analogues of all the other problems faced by the Total View.

So, I conclude, considerations of biographical identity give us reason to shift our credences away from critical-level and critical-range views and towards the Total View. I then note an important practical implication of this shift. It decreases the relative importance of improving humanity’s future conditional on survival and increases the relative importance of ensuring that humanity has a future, by reducing existential risk. I outline the case for thinking that this effect persists – and is important – on a Maximize Expected Choiceworthiness approach to moral uncertainty (MacAskill, Bykvist, and Ord 2020).

I also present objections from identity in Chapter 5, although this time the objections are from personal identity and the target is person-affecting views. On person-affecting views in population ethics, the moral import of a person’s welfare depends on that person’s temporal or modal status (in particular, on whether that person presently exists, actually exists, or will exist regardless of one’s decision). These views typically imply that – all else equal – we are never required to create extra people, or to act in ways that increase the probability of extra people coming into existence.

Arguments against these views have been given before, but none apply to all extant theories (Beckstead 2013, chap. 4; Ross 2015; Greaves 2017; Thomas 2019; Horton 2021; Arrhenius forthcoming, chap. 10). Many of these arguments also rely on cases with three-or-more options (see, for example, Ross 2015; Thomas 2019; Horton 2021; Podgorski 2021). These cases can be difficult to evaluate, and often give rise to conflicting intuitions. In contrast, my arguments tell against all extant person-affecting views and they rely only on intuitions about two-option cases.

My arguments begin with the observation that a person’s temporal or modal status can depend on facts about personal identity: whether a person presently, actually, or necessarily exists in some scenario (or whether they’re harmed by some action) can depend on whether they are identical to some person existing at other times or in other possible worlds. I then use two of Parfit’s puzzles about personal identity to draw out some implausible consequences of person-affecting views. In cases like Combined Spectrum (Parfit 1984, 236–37), such views imply that tiny differences in the physical and psychological connections between persons can engender enormous differences in our moral obligations. And cases like My Division (Parfit 1984, 254–55) give rise to a dilemma for person-affecting views: either they forfeit their seeming-advantages and face analogues of all of the problems faced by impersonal views like Total Utilitarianism, or else they turn out to be not so person-affecting after all. This dilemma undermines much of the motivation for preferring person-affecting views to impersonal views like Total Utilitarianism. I thus conclude that, once we account for the classic objections to person-affecting views, we should prefer impersonal views on balance.

Chapter 6, the final chapter, also concerns person-affecting views. In particular it concerns the procreation asymmetry which (in its deontic reading) states that it is always wrong to create a person who would have a bad life (all else equal) but never wrong not to create a person who would have a good life (all else equal). This view is appealing, but it is also incomplete. The procreation asymmetry does not tell us what to do in cases where creating a person would benefit or harm existing people. Nor does it tell us what to do in cases where we can create more than one person. Instances of the latter include non-identity cases, in which we must choose between creating a person with a good life or a different person with a better life (Parfit 1984, chap. 16). Here is one such case, which we can call ‘One-Shot Non-Identity’:

(1) Amy 1
(2) Bobby 100

Call a person-affecting view ‘wide’ iff it implies that we are required to create the better-off person in such cases. Call a person-affecting view ‘narrow’ iff it implies that we are permitted to create either person.

The defining verdict of narrows views might seem implausible, but many philosophers have made peace with it. These include Joe Horton (2021) and Abelard Podgorski (2021), who each spin out the procreation asymmetry into a complete, narrow person-affecting view. Unfortunately, problems remain. In Chapter 6, I show that Horton’s and Podgorski’s theories have implications that are harder to embrace.

Horton’s view – Avoid Reasonable Objections – implies an especially acute version of the problem of improvable-life avoidance.² It implies that choosing (1) is permissible and choosing (3) is wrong when our options are as follows:

(1) Amy
(2) Bobby 100
(3) Amy  and Bobby

That combination of verdicts seems implausible. (3) is good for Bobby and much better than (1) for Amy. To add some colour to the case, we can suppose that Bobby’s life conditional on (3) features only happiness, and that Amy’s life conditional on (1) is just like her life conditional on (3) except with enough torture at the end to bring her welfare level down from 49 to 1. It is then very difficult to believe that choosing (1) is permissible and choosing (3) is wrong.

Meanwhile, Podgorski’s view – UCV-Defeat-Uncovered – implies the problem of impairable-life acceptance. It implies that choosing each of (2) and (4) is permissible in the following case:

(1) Amy
(2) Bobby 100
(4) Amy  and Bobby

That also seems implausible. Amy’s life conditional on (4) is mediocre, and (4) is much worse than (2) for Bobby. For some extra colour, we can imagine that (4) adds enough torture to bring Bobby’s welfare level down from 100 to 0. With this in mind, it is very hard to believe that choosing (4) is permissible.³

I take the problems of improvable-life avoidance and impairable-life acceptance to be serious challenges to Avoid Reasonable Objections and UCV-Defeat-Uncovered respectively. Not only that (and here I move beyond what is written in Chapter 6), these problems look like bad omens for person-affecting views in general.⁴ That is because it is easy to turn cases like those above into a trilemma for all narrow person-affecting views:

(1) Amy
(2) Bobby 100
(5) Amy  and Bobby

Recall that narrow views permit choosing each of (1) and (2) when these are the only available options. What should they say when (5) is also available?

If choosing (1) remains permissible, the view implies the problem of improvable-life avoidance, since (5) is better for Amy and Bobby’s life conditional on (5) is good. If choosing (5) is permissible, the view implies the problem of impairable-life acceptance, since (5) is mediocre for Amy and much worse than (2) for Bobby. But if (2) is the only permissible option, the view implies Losers Can Dislodge Winners: the addition of an option  can make it wrong to choose a previously-permissible option , even if choosing  is itself wrong in the resulting option-set.⁵ In our case, adding (5) makes choosing (1) wrong, even though choosing (5) is also wrong in this option-set. That seems very strange. Suppose that you find yourself in a situation in which it seems as if (1) and (2) are your only options. Then you need to determine if (5) is also an option in order to determine which of (1) and (2) you may permissibly choose, despite the fact that you know that choosing (5) will be wrong if it is an option. Stranger still, if (1) and (2) are your only options and someone is opposed to your creating Amy, they can make it wrong for you to do so by adding (5) to your option-set, even though choosing (5) is itself wrong in the resulting option-set. For a final peculiarity, suppose that you choose by moving a lever, first to the left or right, and then up or down, with your options arranged as follows:⁶

On the narrow views under consideration, choosing (1) is wrong. But now suppose that a small piece of metal is stuck in the mechanism: if the lever is moved to the left, it cannot be moved back. So, after you move the lever to the left, choosing (5) is no longer an option. At that point, our candidate narrow views imply that choosing (1) is permissible. That is another implausible upshot of Losers Can Dislodge Winners: what you are permitted to do depends not only on your starting set of options but also on the order in which options become unavailable as you make your choices.

The only way to avoid the trilemma of Improvable-Life Avoidance, Impairable-Life Acceptance, and Losers Can Dislodge Winners is to reject the defining claim of narrow person-affecting views: the claim that we are permitted to create either person in one-shot non-identity cases. That does not yet commit us to rejecting person-affecting views wholesale, because we could endorse a wide person-affecting view. These views – recall – state that it is wrong to create the worse-off person in one-shot non-identity cases but permissible (when all else is equal) not to create a person who would have a good life. But wide views are also troubled by non-identity-type cases. To see how, note that wide views imply that choosing each option is permissible in Just Amy, where ‘—’ represents creating no one:

(6) —
(7) Amy 1

Wide views also imply that choosing each option is permissible in Just Bobby:

(8) Bobby 100
(9) —

But now suppose that we choose (7) in Just Amy followed by (9) in Just Bobby. In that case, we have done something with effects on Amy and Bobby equivalent to the effects of choosing (1) in One-Shot Non-Identity: we have created Amy with welfare score 1 and declined to create Bobby with welfare score 100. Wide views imply that creating Amy in One-Shot Non-Identity is wrong. So, what should they say about creating Amy and then declining to create Bobby in Just Amy followed by Just Bobby?

If wide views say that there is nothing wrong with this sequence of choices, then they imply the counterintuitive verdict in the archetypal non-identity case, in which a prospective parent can have a worse-off child now or a better-off child later (Parfit 1984, 358). That prospective parent’s predicament is more accurately modelled as Just Amy followed by Just Bobby than it is as One-Shot Non-Identity, and so our candidate wide view implies that having the worse-off child is permissible.

Here is another bad consequence of the verdict that there is nothing wrong with creating Amy then declining to create Bobby: on the resulting wide view, what we can permissibly do depends on factors that seem morally irrelevant. Suppose, for example, that who comes into existence will be determined by the positions of two levers. By pulling the left lever down, we create Amy with welfare score 1 rather than no one. By pulling the right lever down, we create no one rather than Bobby with welfare score 100.

Our candidate wide view implies that we are permitted to pull the left lever (thereby creating Amy) followed by the right lever (thereby declining to create Bobby). But now suppose that someone lashes the two levers together, so that our only options are pulling both or neither. Then our predicament is transformed into One-Shot Non-Identity, and our wide view implies that pulling both levers is wrong. That is a strange combination of verdicts. As Caspar Hare (2016, 465) writes in another context, ‘Why does it matter, morally, whether you [pull two levers or one]? This seems to me to be too delicate a thing to support so much moral weight.’

Consider one more variation on the case. By declining to pull a lever, we preserve the environment. As a result, 10 billion people exist in the future, each enjoying a wonderful life. By pulling the lever, we destroy the environment. As a result, a different 10 billion people exist in the future, each eking out a mediocre life (Parfit 1984, 361–262). All else is equal, so the case is a scaled-up version of One-Shot Non-Identity and any reasonable wide view will imply that destroying the environment is wrong.

But now modify the case so that there are two levers. Pulling the left lever takes us from preserving the environment to activating the right lever. The default option for the right lever is sterilisation: the present generation will be (with their full consent and without detriment to their quality of life) sterilised, thereby ensuring that there are no future people. Pulling the right lever takes us from sterilisation to environmental destruction: the present generation’s reproductive capacities are saved but the environment is not, so that the resulting 10 billion people have mediocre lives.

On the wide view we are considering, we are permitted to pull the left lever followed by the right lever. We are permitted to do in two steps what we are forbidden from doing in one.

So, consider instead another class of wide views, on which there is something wrong with creating Amy and then later declining to create Bobby. Perhaps the latter choice is made wrong by the former, or perhaps – though each choice is permissible – performing the whole sequence is not. This claim has implications that are unlikely to be welcomed by those inclined towards the procreation asymmetry. It implies that a parent who previously chose to create Amy in Just Amy now has to create Bobby in Just Bobby to avoid wrongdoing: failing to create Bobby would either be wrong (in virtue of the parent’s prior decision to create Amy) or it would complete a wrong sequence of choices. Or suppose that a friend is considering having a child and comes to you for moral advice. On this new class of wide views, you will not only need to ask your friend the usual questions. You will also need to ask them about their past procreative choices. If in the past your friend had a child with a worse life than this new child would have, your friend must have the new child to avoid wrongdoing. If in the past your friend turned down the chance to have a child with a better life than this new child would have, your friend must not have the new child. These implications are counterintuitive, and they remain so when we stipulate that all else was and is equal in each of your friend’s choices.

Perhaps there is a way for wide views to slip through the horns of this dilemma. Perhaps, for example, there is something wrong with creating Amy and then declining to create Bobby iff you foresee at the time of creating Amy that you will later have the chance to create Bobby, or iff you intend at the time of creating Amy to later decline to create Bobby. These principles might yield more plausible verdicts in the cases above, but any exoneration seems partial at best. The implications mentioned in the last paragraph remain counterintuitive when we stipulate that your friend foresaw the choices that they would face. And although intentions are often relevant to questions of blameworthiness, it is doubtful whether they are ever relevant to questions of permissibility.⁷ Certainly, what you foresee or intend does not matter to Amy or Bobby: the people whose existence is at stake. We might also worry that these kinds of wide views incentivise agents to purposefully hamper their own foresight or smother their own intentions, so as to keep more of their options permissible in later choices. Perhaps we can add to our wide view some principle proscribing these mind-moves, but any such addition will only strengthen the case that I am trying to make here: that wide views force on us an unseemly preoccupation with the motions of our own minds and hands.

That is why I say that the problems of improvable-life avoidance and impairable-life acceptance look like bad omens for person-affecting views in general. Narrow person-affecting views must face one of these problems, or else imply Losers Can Dislodge Winners along with all its attendant peculiarities. Wide person-affecting views, meanwhile, remain undecided even when we know all the facts about who lives and how well. Their verdicts wait on the answers to questions that seem morally irrelevant: questions like ‘Did you miss the opportunity to have a happier child many years earlier?’ and ‘Do you propose to destroy the environment by pulling two levers or one?’.

To avoid these problems, we must reject person-affecting views. We must claim that (at least in some cases, and where all else is equal) we are required to create people who would enjoy good lives. This claim is not nearly as counterintuitive as it is sometimes taken to be. It should not be mistaken for the claim that prospective parents in our world are required to have children. In those cases, all else is far from equal (Chappell 2017, 168–70; Francis 2021, sec. 2). The requirement is operational only in cases like the following. By pressing a particular button, you would create a flourishing society of people far away. Each member of this society – from the first generation until the last – is guaranteed to enjoy a wonderful life, and to have no effect on the lives of anyone outside the society. By leaving the button unpressed, you would prevent this flourishing society from ever existing. In this case, it seems to me that refusing to press the button would be wrong.⁸ Certainly, the view that doing so would be wrong is more plausible than the implications of person-affecting views drawn out above.

That concludes my quick case against person-affecting views. I hope to present the argument more comprehensively in future work. Let me end this introduction by mentioning two charms of population ethics as a field of study.

First, you can prove theorems. You need not content yourself with sketching out some plausible (though imprecise) premises and drawing a natural (though not inevitable) conclusion. You can lay down axioms and demonstrate that certain claims follow. Better yet, some of the theorems that can be proved are astounding, with nigh-on-undeniable premises together guaranteeing a nigh-on-unbelievable conclusion. Arrhenius’s impossibility theorems are perhaps the best example. In my darker moods, it sometimes feels to me as if philosophy is a magic trick in which the magician is fooled most of all. But even then I figure that, if I am to be fooled, it might as well be with these marvellous tricks.

The second charm of population ethics is that it concerns things that are important: life and death, joy and misery, survival and extinction. Not only that, but we find ourselves living at a time where our views on population ethics bear significantly on the broader question of how we should spend our days. I have come to think it likely that we live either at the very end or the very beginning of human history, and that shifting the relevant probabilities is within our power. But doing so takes time, money, effort, and thought: each of which is called for by other urgent problems. So, we need to think carefully about what to do. Thinking carefully about population ethics is an important part of that.

References

Arrhenius, Gustaf. 2000a. ‘An Impossibility Theorem for Welfarist Axiologies’. Economics & Philosophy 16 (2): 247–66.

———. 2000b. ‘Future Generations: A Challenge for Moral Theory’. PhD Thesis, Uppsala University.

———. 2009. ‘One More Axiological Impossibility Theorem’. In Logic, Ethics and All That Jazz. Essays in Honour of Jordan Howard Sobel, edited by Lars-Göran Johansson, Jan Österberg, and Ryszard Sliwinski, 23–37. Uppsala: Uppsala Philosophical Studies.

———. 2011. ‘The Impossibility of a Satisfactory Population Ethics’. In Descriptive and Normative Approaches to Human Behavior, edited by Ehtibar N. Dzhafarov and Lacey Perry, 1–26. Singapore: World Scientific Publishing Company.

———. forthcoming. Population Ethics: The Challenge of Future Generations. Oxford: Oxford University Press.

Beckstead, Nick. 2013. ‘On the Overwhelming Importance of Shaping the Far Future’. PhD Thesis, Rutgers, New Jersey: Rutgers University. http://dx.doi.org/doi:10.7282/T35M649T.

Broome, John. 2004. Weighing Lives. Oxford: Oxford University Press.

Carlson, Erik. 2022. ‘On Some Impossibility Theorems in Population Ethics’. In The Oxford Handbook of Population Ethics, edited by Gustaf Arrhenius, Krister Bykvist, Tim Campbell, and Elizabeth Finneron-Burns. Oxford: Oxford University Press.

Chappell, Richard Yetter. 2017. ‘Rethinking the Asymmetry’. Canadian Journal of Philosophy 47 (2–3): 167–77.

Francis, Tomi. 2021. ‘How Compelling Is the Procreation Asymmetry?’

Greaves, Hilary. 2017. ‘Population Axiology’. Philosophy Compass 12 (11).

Gustafsson, Johan E. 2020. ‘Population Axiology and the Possibility of a Fourth Category of Absolute Value’. Economics & Philosophy 36 (1): 81–110.

Handfield, Toby, and Wlodek Rabinowicz. 2018. ‘Incommensurability and Vagueness in Spectrum Arguments: Options for Saving Transitivity of Betterness’. Philosophical Studies 175 (9): 2373–87.

Hare, Caspar. 2016. ‘Should We Wish Well to All?’ The Philosophical Review 125 (4): 451–72.

Horton, Joe. 2021. ‘New and Improvable Lives’. The Journal of Philosophy 118 (9): 486–503.

Huemer, Michael. 2008. ‘In Defence of Repugnance’. Mind 117 (468): 899–933.

Kitcher, Philip. 2000. ‘Parfit’s Puzzle’. Noûs 34 (4): 550–77.

MacAskill, William, Krister Bykvist, and Toby Ord. 2020. Moral Uncertainty. Oxford: Oxford University Press.

Nebel, Jacob M. 2019. ‘An Intrapersonal Addition Paradox’. Ethics 129 (2): 309–43.

———. 2021. ‘Totalism without Repugnance’. In Ethics and Existence: The Legacy of Derek Parfit, edited by Jeff McMahan, Tim Campbell, James Goodrich, and Ketan Ramakrishnan. Oxford: Oxford University Press. https://philpapers.org/archive/NEBTWR.pdf.

Ng, Yew-Kwang. 1989. ‘What Should We Do About Future Generations? Impossibility of Parfit’s Theory X’. Economics & Philosophy 5 (2): 235–53.

Parfit, Derek. 1984. Reasons and Persons. Oxford: Clarendon Press.

———. 1986. ‘Overpopulation and the Quality of Life’. In Applied Ethics, edited by Peter Singer, 145–64. Oxford: Oxford University Press.

Podgorski, Abelard. 2021. ‘Complaints and Tournament Population Ethics’. Philosophy and Phenomenological Research. https://doi.org/10.1111/phpr.12860.

Ross, Jacob. 2015. ‘Rethinking the Person-Affecting Principle’. Journal of Moral Philosophy 12 (4): 428–61.

Sen, Amartya. 2017. Collective Choice and Social Welfare. Expanded Edition. London: Penguin.

Thomas, Teruji. 2018. ‘Some Possibilities in Population Axiology’. Mind 127 (507): 807–32.

———. 2019. ‘The Asymmetry, Uncertainty, and the Long Term’. GPI Working Paper No. 11-2019. https://globalprioritiesinstitute.org/teruji-thomas-the-asymmetry-uncertainty-and-the-long-term/.

———. 2022. ‘The Asymmetry, Uncertainty, and the Long Term’. Philosophy and Phenomenological Research. https://onlinelibrary.wiley.com/doi/full/10.1111/phpr.12927.

Thomson, Judith Jarvis. 1991. ‘Self-Defense’. Philosophy & Public Affairs 20 (4): 283–310.

Thomson, Judith Jarvis. 1999. ‘Physician‐Assisted Suicide: Two Moral Arguments’. Ethics 109 (3): 497–518. https://doi.org/10.1086/233919.

1. Technically, this is just the positive half of Archimedeanism about Populations. The negative half is as follows: for any population X and any contributively bad life y, there is some number m such that a population consisting of m lives equally good as y is worse than X.

2. See Ross (2015) for the original problem.

3. Note also that, in this case, UCV-Defeat-Uncovered is more permissive about making people worse off in order to create extra people than even Total Utilitarianism. On Total Utilitarianism, choosing (4) is wrong.

4. More precisely, the problems look like bad omens for all person-affecting views which imply the positive half of the deontic procreation asymmetry: the claim that it is always permissible not to create a person who would have a good life (all else equal). From now on, I leave this qualification implicit.

5. This condition is the negation of Podgorski’s (2021, 19) Losers Can’t Dislodge Winners.

6. I borrow this kind of case from Thomas (2022, 16), who uses it to bring out the implausibility of theories that violate a different condition: Sen’s (2017, 63) Property α (otherwise known as ‘Basic Contraction Consistency’).

7. See Thomson (1991, 293; 1999, 514–15) for cases making this point.

8. See Chappell (2017, 170) for a similar case and claim.