1. Introduction

According to person-affecting views (PAVs) in population ethics, adding happy people to the world is morally neutral. It’s neither good nor bad.

Are PAVs true? The question is important.

If PAVs are true, then the EA community is likely spending way too much time and money on reducing x-risk. After all, a supposed major benefit of reducing x-risk is that it increases the chance that lots of happy people come into existence. If PAVs are true, this ‘benefit’ is no benefit at all.

By contrast, if PAVs are false, then the EA community (and the world at large) is likely spending way too little time and money on reducing x-risk. After all, the future could contain a lot of happy people. So if adding happy people to the world is good, reducing x-risk is plausibly very good.

And if PAVs are false, it’s plausibly very important to ensure that people believe that PAVs are false. In spreading this belief, we reduce the risk of the following non-extinction failure-mode: humanity successfully navigates the transition to advanced AI but then creates way too few happy people.

So it’s important to figure out whether PAVs are true or false. The EA community has made efforts on this front, but the best-known arguments leave something to be desired. In particular, the arguments against PAVs mostly only apply to specific versions of these views.^[1] Many other PAVs remain untouched.

Nevertheless, I think there are strong arguments against PAVs in general. In this post, I sketch out some of my favourites.

2. The simple argument

Before we begin, a quick terminological note. In this post, I use ‘happy people’ as shorthand for ‘people whose lives are good overall’ and ‘miserable people’ as shorthand for ‘people whose lives are bad overall.’

With that out the way, let’s start with a simple argument:

The simple argument

1. Some things are good (for example: happiness, love, friendship, beauty, achievement, knowledge, and virtue).

2. By creating happy people, we can bring more of these good things into the world.

3. And the more good things, the better.

C1. Therefore, creating happy people can be good

C2. Therefore, PAVs are false.

2.1. The classic PAV response

Advocates of PAVs reject this simple argument. The classic PAV response begins with the following two claims:^[2]

The Person-Affecting Restriction

One outcome can’t be better than another unless it’s better for some person.

Existence Anticomparativism

Existing can’t be better or worse for a person than not-existing.

Each of these two claims seems tough to deny. Consider first the Person-Affecting Restriction. How could one outcome be better than another if it’s not better for anyone? Now consider Existence Anticomparativism. If existing could be better for a person than not-existing, then it seemingly must be that not-existing would be worse for that person than existing. But how can anything be better or worse for a person that doesn’t exist?^[3]

So each of the two claims seems plausible, and they together imply that premise 3 of the simple argument is false: sometimes, bringing more good things into the world doesn’t make the world better. Here’s why. By creating a happy person, we bring more good things into the world. But our action isn’t better for this happy person (by Existence Anticomparativism), nor is it better for anyone else (by stipulation), and so it isn’t better for the world (by the Person-Affecting Restriction).

By reasoning in this way, advocates of PAVs can defuse the simple argument and defend their claim that creating happy people isn’t good.

2.2. The problem with the classic PAV response

Now for the problem. The Person-Affecting Restriction and Existence Anticomparativism don’t just together imply that creating happy people isn’t good. They also together imply that:

(a) Creating miserable people isn’t bad.

(b) Creating barely happy people isn’t worse than creating different, very happy people.^[4]

Here’s why the Person-Affecting Restriction and Existence Anticomparativism together imply (a). Suppose that we create a miserable person. Our action isn’t worse for this miserable person (by Existence Anticomparativism), nor is it worse for anyone else (by stipulation), and so it isn’t worse for the world (by the Person-Affecting Restriction). So creating miserable people isn’t bad.

And here’s why the Person-Affecting Restriction and Existence Anticomparativism together imply (b). Suppose we have a choice between (i) creating a set of barely happy people, and (ii) creating an entirely different set of very happy people. Suppose that we create the barely happy people. Our action isn’t worse for the very happy people (by Existence Anticomparativism), nor is it worse for anyone else (by stipulation), and so it isn’t worse for the world (by the Person-Affecting Restriction). So creating barely happy people isn’t worse than creating different, very happy people.

But each of (a) and (b) seems false. It certainly seems like creating miserable people is bad, and that creating barely happy people is worse than creating different, very happy people. And that suggests that at least one of our premises is false: either the Person-Affecting Restriction or Existence Anticomparativism. Although these claims each seemed appealing at first, they together imply some very counterintuitive conclusions, so at least one of them must be incorrect.

And if at least one of these claims is incorrect, then the classic PAV response to the simple argument is undercut. After all, the classic response uses both the Person-Affecting Restriction and Existence Anticomparativism to object to premise 3 of the simple argument. If at least one of those claims is incorrect, then the objection to premise 3 no longer works, and so premise 3 (‘the more good things, the better’) is back to looking pretty compelling. And since premises 1 and 2 are hard to doubt, the simple argument as a whole is back to looking pretty compelling.

How might advocates of PAVs respond now? They could modify Existence Anticomparativism. The original claim is: ‘Existing can’t be better or worse for a person than not existing.’ Advocates of PAVs could replace it with ‘Existing can’t be better for a person than not existing.’ Then Existence Anticomparativism and the Person-Affecting Restriction would no longer together imply that creating miserable people isn’t bad. But if advocates of PAVs make this response, then they’ll have to find some way to explain the resulting asymmetry: if existing can be worse for a person than not existing, why can't it be better?^[5]

And in any case, modifying Existence Anticomparativism doesn’t help PAVs avoid the other counterintuitive conclusion: creating barely happy people isn’t worse than creating different, very happy people. Advocates of PAVs will have to find some other way of dealing with that. This other counterintuitive conclusion is the famous non-identity problem for PAVs, and I’ll discuss it more below. Before that, let’s consider another argument against PAVs.

3. Tomi’s argument that creating happy people is good

This argument comes from my colleague Tomi Francis.^[6] Let's represent lives that are neither good nor bad with a welfare level of 0, and let's represent wonderful lives with a welfare level of 100. Suppose that a hundred people already exist. You’re considering creating ten billion extra people. You have three options: A, B, and C. In A, the hundred already-existing people have welfare level 40, and only they exist. In B, the hundred already-existing people have welfare level 41, and the ten billion extra people also have welfare level 41. In C, the hundred already-existing people have welfare level 40, and the ten billion extra people have welfare level 100.

Here’s the argument. B is better than A, because B is better than A for the hundred already-existing people, and the ten billion extra people all have happy lives. And C is better than B, because moving to C makes a hundred people's lives slightly worse and ten billion people's lives much better. And betterness is transitive: if an outcome X is better than an outcome Y, and Y is better than an outcome Z, then X is better than Z. So since C is better than B, and B is better than A, C is better than A. And C and A are identical except for the extra ten billion people living happy lives in C. Therefore, it’s good to add happy people, and hence PAVs are false.

Tomi’s argument presents a new challenge to PAVs. The argument doesn’t employ any premise like ‘The more good things, the better,’ and so it can’t be defused by the Person-Affecting Restriction and Existence Anticomparativism.

3.1. A PAV response

How might advocates of PAVs respond to Tomi’s argument? One possibility is to claim that betterness is option-set dependent: whether an outcome X is better than an outcome Y can depend on what other outcomes are available as options to choose. In particular, advocates of PAVs could claim:

• B is better than A when B and A are the only options
• B is not better than A when C is also an option.

And advocates of PAVs could defend the second bullet-point in the following way: when C is available, B harms (or is unjust to) the ten billion extra people, because these extra people are better off in C.^[7] And this harm/injustice prevents B from being better than A.

3.2. A problem with the PAV response

That’s a possible response. I don’t think it’s especially convincing. Choosing B doesn’t seem especially unjust to the ten billion extra people, given that they enjoy the same good welfare level as everyone else. Certainly, it doesn’t seem like the kind of injustice that should lead us to choose A instead, thereby not creating the extra people at all and making the already-existing people worse off.

And choosing B harms the extra ten billion people only in a technical sense of the word, according to which a person is harmed if and only if this person is worse off than they could have been. But this technical sense of the word ‘harm’ differs significantly from our ordinary sense of the word, as is made clear by the following example. Suppose I could give a total stranger £0, £10 or £11. In the technical sense, I’d harm this stranger if I gave them £10, since I leave them worse off than they could have been. But I needn’t be harming them in the ordinary sense, and the same goes for the ten billion extra people in B. Their lives at welfare level 41 could be lives of moderate happiness, with little suffering.

In sum, I think Tomi’s argument presents a real challenge to PAVs.

4. The non-identity problem

Now let’s get back to the non-identity problem. Here’s a recap of how that goes. If the Person-Affecting Restriction and Existence Anticomparativism are both true, then creating a barely happy person is not worse than creating a different, very happy person. That conclusion seems implausible, and so casts doubt on the premises. How might advocates of PAVs respond?

One response is to bite the bullet. Advocates of PAVs can embrace the implausible-seeming conclusion, and thereby hold on to the Person-Affecting Restriction and Existence Anticomparativism. But that’s not as straightforward as it seems, because here’s another, independent argument from Tomi against the implausible-seeming conclusion.

4.1. Tomi’s argument that creating happier people is better

Suppose that Adam already exists. You’re considering creating Eve or Steve. You have three options: D, E, and F. In D, Adam has welfare level 99 and Eve will be created with welfare level 100. In E, Adam has welfare level 100 and Eve will be created with welfare level 99. In F, Adam has welfare level 99 and Steve will be created with welfare level 1.

Here’s the argument. D is equally good as E, because D and E just swap Adam’s and Eve’s welfare levels, and Adam and Eve are equally morally important. And E is better than F, because E is better for Adam, and it replaces worse-off Steve with better-off Eve. And betterness is transitive in the relevant sense: D is equally good as E, and E is better than F, so D is better than F. And Adam’s welfare level is the same in D as in F; the only difference is that D replaces worse-off Steve with better-off Eve. So creating a very happy person is better than creating a different, barely happy person. Since the combination of the Person-Affecting Restriction and Existence Anticomparativism implies the contrary, at least one of these latter two claims must be false.

4.1.1. A PAV response

So advocates of PAVs can’t just bite the bullet on the non-identity problem. They also have to reckon with Tomi’s argument. How might they do that?

One possibility is to shift gears. So far, we’ve been arguing about the axiological facts: facts about what’s good and bad, better and worse. But advocates of PAVs can claim that it’s the deontic facts that are central to morality: facts about what’s morally permissible and morally required. This shift in gears gives PAVs a little more room to manoeuvre, since one might well think that we’re not always morally required to do what’s best. In particular, PAVs could concede that creating better-off Eve is better than creating worse-off Steve, but nevertheless maintain that we’re morally permitted to create worse-off Steve. Or PAVs could concede that creating happy people is good, but nevertheless maintain that we’re morally permitted not to create them (in cases where all else is equal). Now let’s consider these views.

5. Deontic PAVs

At the start of this post I wrote that, according to person-affecting views (PAVs), adding happy people to the world is neither good nor bad. I can now be more precise and call these ‘axiological PAVs’. Related but distinct are deontic PAVs, which say that (in cases where all else is equal) we’re morally permitted but not required to add happy people to the world. As I noted above, retreating to purely deontic PAVs offers a means of escape from some of the arguments of the previous sections.

But there are other arguments that tell against deontic PAVs. To explain these arguments, let’s first distinguish between two kinds of deontic PAV. Consider the following case:

Non-Identity

(1) Amy 1

(2) Bobby 100

Here option (1) is creating Amy with a barely good life at welfare level 1. Option (2) is creating Bobby with a wonderful life at welfare level 100. The first kind of deontic PAV – a narrow view – says that each option is permissible. We’re morally permitted to create the person with the worse life.^[8] The second kind of deontic PAV – a wide view – says that only (2) is permissible. We’re morally required to create the person with the better life.^[9]

I’ll sketch out arguments against each of these views in turn. This paper presents the arguments in more detail.

5.1. A trilemma for narrow views

Here’s a problem for narrow views. Consider:

Expanded Non-Identity

(1) Amy 1

(2) Bobby 100

(3) Amy 10, Bobby 10

Here we’ve added a third option to Non-Identity. The first two options are as before: create Amy with a barely good life at welfare level 1 or create Bobby with a wonderful life at welfare level 100. The new third option is to create both Amy and Bobby with mediocre lives at welfare level 10.

Narrow views imply that each of (1) and (2) are permissible when these are the only available options. What should they say when (3) is also an option? I’ll argue that they must say at least one of three implausible things, so that narrow views face a trilemma.

Option (1) remains permissible

The first thing they could say is that option (1) – creating Amy with a barely good life at welfare level 1 – remains permissible when we move from Non-Identity to Expanded Non-Identity. But that claim implies:

Permissible to Choose Dominated Options

There are option sets in which we’re permitted to choose some option X even though there’s some other available option Y that dominates X. That is to say, (i) everyone in X is better off in Y, (ii) everyone who exists in Y but not X has a
good life, and (iii) Y is perfectly equal.

That’s because (1) is dominated by (3): (3) creates only people with good lives, it leads to perfect equality, and it’s better than (1) for Amy: the only person who exists in (1). It thus seems implausible that (1) is permissible.

Option (3) is permissible

Here’s something else that narrow views could say about Expanded Non-Identity: option (3) – creating Amy and Bobby with mediocre lives at welfare level 10 – is permissible. But that claim implies:

Permissible to Do Serious Harm for Mediocre Creation

There are option sets in which we’re permitted to choose some option X even though – relative to some other available option Y – all X does is seriously harm one person and create another person with a mediocre life.

That’s because (3) is mediocre for Amy and much worse than (2) for Bobby: Bobby’s welfare level is 100 in (2) and 10 in (3). And we can imagine variations on Expanded Non-Identity in which Bobby’s welfare level in (2) is arbitrarily high. The higher Bobby’s welfare level in (2), the more implausible it is to claim that we’re permitted to choose (3).

Only option (2) is permissible

Now we can complete the trilemma for narrow views. If neither of (1) and (3) is permissible in Expanded Non-Identity, it must be that only (2) is permissible. But if only (2) is permissible, then narrow views imply:

Losers Can Dislodge Winners:

Adding some option X to an option set can make it wrong to choose a previously-permissible option Y, even though choosing X is itself wrong in the resulting option set.

That’s because narrow views imply that each of (1) and (2) is permissible in Non-Identity. So if only (2) is permissible in Expanded Non-Identity, then adding (3) to our option set has made it wrong to choose (1) even though choosing (3) is itself wrong in Expanded Non-Identity.

That’s a peculiar implication. It’s a deontic version of an old anecdote about the philosopher Sidney Morgenbesser. Here’s how that story goes. Morgenbesser is offered a choice between apple pie and blueberry pie, and he orders the apple. Shortly after, the waiter returns to say that cherry pie is also an option, to which Morgenbesser replies, ‘In that case, I’ll have the blueberry.’

That’s a strange pattern of preferences. The pattern is even stranger in our deontic case. Imagine instead that the waiter is offering Morgenbesser the options in Expanded Non-Identity.^[10] Initially the choice is between (1) and (2), and Morgenbesser permissibly opts for (1). Then the waiter returns to say that (3) is also an option, to which Morgenbesser replies, ‘In that case, I’m morally required to switch to (2).’ The upshot is that the waiter can force Morgenbesser’s hand by adding options that are wrong to choose in the resulting option set. And turning the case around, the waiter could expand Morgenbesser’s menu of permissible options by taking wrong options off the table. That seems implausible.

Summarising the trilemma

Now the trilemma for narrow person-affecting views is complete and I can summarise. If these views say that (1) is permissible in Expanded Non-Identity, they imply that it’s Permissible to Choose Dominated Options. If they say that (3) is permissible, they imply that it’s Permissible to Do Serious Harm for Mediocre Creation. And if they say that only (2) is permissible, they imply Losers Can Dislodge Winners. Each of these implications is implausible.

5.2. A trilemma for wide views

Now let’s consider wide views. Recall that these views say that we’re morally required to create the better-off person in cases like Non-Identity:

Non-Identity

(1) Amy 1

(2) Bobby 100

Wide views thus avoid the trilemma above. They can say that only (2) is permissible in Expanded Non-Identity without implying Losers Can Dislodge Winners. However, wide views imply a trilemma of their own. To see how, consider first:

One-Shot Non-Identity

This case is a cosmetic variation of Non-Identity in which Amy’s and Bobby’s existence will be determined by the positions of two levers. By leaving the left lever up, we decline to create Amy. By pulling the left lever down, we create her at welfare level 1. By leaving the right lever up, we create Bobby at welfare level 100. By pulling the right lever down, we decline to create him. Crucially, the levers are lashed together, so our only options are pulling both levers or pulling neither. Wide views thus imply that pulling both levers is wrong. After all, pulling both levers means creating Amy at welfare level 1 and declining to create Bobby at welfare level 100.

Now consider:

Two-Shot Non-Identity

In this case, the levers are no longer lashed together. We first decide whether to pull the first lever, lock that choice in, and then decide whether to pull the second lever.

I now use these cases to argue against wide person-affecting views. Assume – for contradiction – any wide person-affecting view. Per the ‘wide’ part of such views, it’s wrong to pull both levers in One-Shot Non-Identity. Now assume that the wrongness of pulling both levers doesn’t depend on whether the levers are lashed together. Then it’s also wrong to pull both levers in Two-Shot Non-Identity. Assume also that it’s not wrong to pull the first lever in Two-Shot Non-Identity. Then if we’ve pulled the first lever, it must be wrong to pull the second lever. Finally, assume that the wrongness of pulling the second lever doesn’t depend on past choices. Then it must be wrong to pull the second lever regardless of whether we’ve pulled the first lever. But if that’s the case, then we’re required to create Bobby at welfare level 100. After all, that’s what we do by declining to pull the second lever. This verdict is contrary to the ‘person-affecting’ part of wide person-affecting views. We’ve reached a contradiction.

Therefore, advocates of wide views must reject at least one of my argument’s three assumptions. I now argue that doing so commits them to saying at least one of three implausible things.

Wrongness Depends on Lever-Lashing

To reject the first assumption, advocates of wide views must claim that:

Wrongness Depends on Lever-Lashing

The wrongness of pulling both levers (thereby creating Amy and declining to create Bobby) depends on whether the levers are lashed together. When the levers are lashed together, pulling both levers is wrong. When the lashing is cut, pulling both levers is permissible.

This response is a deontic analogue of myopic choice (McClennen 1990, 12). Myopic choosers sometimes do in two steps what they’d never do in one. The response implies that you’re sometimes permitted to do in two steps what you’re forbidden from doing in one.

Like myopic choice, Wrongness Depends on Lever-Lashing is unpromising on its face. Pulling both levers should either be wrong in both cases or permissible in both cases. It shouldn’t matter whether we can pull them one after the other. After all, it doesn’t matter to Amy or Bobby whether you pull the levers one after the other.

Pulling the First Lever is Wrong

To reject the second assumption of my argument, advocates of wide views must claim that:

Pulling the First Lever is Wrong

In Two-Shot Non-Identity, pulling the first lever (thereby creating Amy) is wrong.

That allows advocates of wide views to say that pulling the second lever is permissible. This response takes inspiration from sophisticated choice (McClennen 1990, 12). Sophisticated choosers predict the choices that they’d make at later timesteps and use these predictions to determine the options available to them at earlier timesteps. This process sometimes prevents them from making earlier choices that they’d otherwise have made. The response in question puts a deontic spin on this general idea. Perhaps the most natural way of making it precise is as follows. Since you might later decline to create Bobby, creating Amy exposes you to a risk of creating only Amy: the one course of action that wide views deem wrong in One-Shot Non-Identity. By contrast, if you don’t create Amy, there’s no chance that you’ll create only Amy and hence no chance that you’ll do what’s wrong according to wide views. Therefore, it’s wrong to pull the first lever and create Amy.

This response is implausible. Pulling the first lever creates Amy with a good life at welfare level 1, and it leaves open the possibility of later creating Bobby with a wonderful life at welfare level 100. The response is even more implausible in a minor variant of Two-Shot Non-Identity in which Amy’s welfare level is 99 instead of 1. In this case, it’s especially hard to believe that creating Amy is wrong. And supposing (as seems natural) that creating Bobby can’t undo any prior wrongness of creating Amy, the resulting wide view implies that it’s impossible to create both Amy and Bobby without acting wrongly. That seems very counterintuitive.

Generalising beyond Two-Shot Non-Identity, the wide views in question prohibit creating a person with a good life whenever you’ll later have the chance to create a person with an even better life, even if creating the first person doesn’t preclude creating the second person. In cases where all else is equal, prospective parents are forbidden from having children until they’ve hit the peak of their welfare-providing powers. That verdict seems undesirable.

Wrongness Depends on First Lever

To reject the third assumption of my argument, advocates of wide views must claim that:

Wrongness Depends on First Lever

Pulling the second lever (thereby declining to create Bobby) is wrong if and only if you’ve previously pulled the first lever (thereby creating Amy).

The response is thus a deontic analogue of resolute choice (McClennen 1990, 13). Resolute choosers sometimes turn down options that they might have chosen had their past choices been different. The response implies that you’re sometimes forbidden from choosing options that you could permissibly have chosen had your past choices been different.

The first thing to say about this response is that it retreats from a deontic person-affecting view, at least as I’ve characterised deontic person-affecting views in this post. That’s because the response concedes that there are cases in which (all else equal) we’re required to create people who would enjoy good lives. Two-Shot Non-Identity is one such case. If you’ve previously created Amy, you’re required to create Bobby. This implication won’t be welcomed by those inclined towards person-affecting views. After all, it runs counter to a major motivation for such views: granting broad latitude to those in a position to create good lives.

The second thing to say about the response is more straightforward: it seems implausible to claim that we’re required to create a better-off person if and only if we previously created a worse-off person. To pump intuitions here, suppose that a friend is considering having a child and comes to you for moral advice. Per the response, you not only need to ask your friend the usual questions about the child’s likely quality of life and how the child might affect existing people. You also need to ask your friend 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. And now reversing the order of the cases: if in the past your friend declined to have a child with a better life than this new child would have, your friend must not have the new child. This latter implication seems especially implausible. The new child’s life could be wonderful, but if your friend previously declined to have a child with an even better life, your friend is not even permitted to create them. The response thus implies that there are cases in which (all else equal) we are not even permitted to create a person who would enjoy a wonderful life.

5.3. Summarising the case against deontic PAVs

My argument against deontic PAVs is a dilemma over trilemmas. The first fork is Non-Identity: narrow views are those person-affecting views that permit us to create the worse-off person, and wide views are those person-affecting views that require us to create the better-off person. 

The fork for narrow views is a trilemma centred around Expanded Non-Identity. These views imply Permissible to Choose Dominated Options, or Permissible to Do Serious Harm for Mediocre Creation, or Losers Can Dislodge Winners.

The fork for wide views is a trilemma centred around Two-Shot Non-Identity. These views imply Wrongness Depends on Lever-Lashing, or Pulling the First Lever is Wrong, or Wrongness Depends on First Lever.

6. Conclusion

It’s important to figure out whether person-affecting views (PAVs) are true or false. If PAVs are true, we should be spending less on reducing x-risk. If PAVs are false, we (and the world at large) should be spending more on reducing x-risk, and we should be wary of the potential post-AGI failure-mode of creating way too few happy people.

I think that PAVs are false, but I also think that extant arguments against PAVs are weak. In this post, I’ve sketched out some arguments that I like better. I began with the simple argument and laid out problems for the classic PAV response. I then explained two arguments from Tomi Francis. These arguments imply that it’s good to create happy people, and better to create happier people. I then considered two kinds of deontic PAV – narrow views and wide views – and presented arguments against those. Narrow views face a trilemma in my Expanded Non-Identity case. Wide views face a trilemma in my Two-Shot Non-Identity case.

1. ^{^}

    These arguments include Beckstead (2013, chapter 4), Greaves (2017, section 5), and  MacAskill (2022, chapter 8).

2. ^{^}

    See Narveson (1967)  for an early version of this response.

3. ^{^}

    Broome (1999, p.168) makes this argument. Greaves and Cusbert (2022) respond.

4. ^{^}

    The fact that the Person-Affecting Restriction and Existence Anticomparativism together imply (b) is known as the ‘non-identity problem’.

5. ^{^}

    Nebel (2019) offers one explanation.

6. ^{^}

    See his paper for more detail.

7. ^{^}

    See (for example), Roberts (2011), Meacham (2012), and Frick (2022).

8. ^{^}

    See (for example) Heyd (2009), Roberts (2011), Boonin (2014), Mogensen (2019), Horton (2021), Podgorski (2021), and Spencer (2021).

9. ^{^}

    See (for example) Hare (2007), Meacham (2012), Parfit (2017), and Frick (2020).

10. ^{^}

     It’s a very unusual restaurant.