TL;DR

In population ethics, the total view entails the repugnant conclusion. Some people argue that, since the repugnant conclusion is obviously false, the total view is incorrect. I sum up two objections by Michael Huemer to the claim that the repugnant conclusion is obviously false.

First, its repugnance may be explained not by its falsehood, but by our biases and cognitive limitations.

1. Instead of asking ourselves if A is better than Z, we tend to ask which of the two worlds we would personally ‌prefer to live in.
2. Scope insensitivity and our difficulty in compounding tiny quantities make the repugnant conclusion unintuitive.
3. We tend to underestimate the quality of a barely worth living life.

Second, the repugnant conclusion necessarily follows from highly plausible moral principles. It is impossible to avoid it without accepting at least one of the following:

1. Cyclical preferences.
2. Equality in the distribution of utility is intrinsically bad.
3. A situation that Pareto dominates another one is not preferable to the Pareto dominated one.

Why I wrote this post

I’m a facilitator for the EAVP Intro Program. When I discuss longtermism with participants, population ethics usually comes up. On a few occasions, the repugnant conclusion has been brought up as an objection to the total view.

A few months ago, I wrote a paper for university arguing against this objection. Making a post out of it is a quick task, and it seems useful to have a resource on the forum to share with Intro Program participants (or anyone who might be interested) when they bring up this argument. So here it is!

What is the repugnant conclusion?

The repugnant conclusion was originally stated by Derek Parfit (1984, p.388):

For any possible population of at least ten billion people, all with a very high quality of life, there must be some much larger imaginable population whose existence, if other things are equal, would be better, even though its members have lives that are barely worth living.

This clearly follows from the total view, according to which the value of a world X is represented by the function

$Valu{e}_X=N_X{W}_X$

Where N_X is the number of people who live in X and W_X is their average well-being level.

Consider two hypothetical worlds, A and Z, to which we assign some arbitrary well-being levels measured on a cardinal scale. Positive numbers represent lives worth living, while negative ones represent lives not worth living. A contains ten billion people (N_A) with a well-being level of 100 (W_A). Z contains the same population of A plus 9.99 trillion people, for a total of ten trillion people (N_Z), all with a well-being level of 0.2 (W_Z). A simple multiplication reveals that:

$Valu{e}_A={10}^{10}\cdot 100={10}^{12}<Valu{e}_Z={10}^{13}\cdot 0.2=2\cdot {10}^{12}$

Therefore, the total view favors world Z over world A, and is thus committed to the repugnant conclusion. 

According to Tännsjö (2002, p.1), "repugnant" is to be understood as "obviously false". If the repugnant conclusion is actually repugnant in this sense, then the total view must be wrong, for it entails such a false claim.

In the rest of this post, I will sum up two objections by Michael Huemer to the claim that the repugnant conclusion is obviously false.

Our unrepugnant intuition is biased

Huemer (2008, p.907) claims that our "unrepugnant intuition" that A is better than Z may not be as reliable as it first appears to be. When facing the choice between A and Z, several biases and cognitive limitations alter our judgment. Huemer individuates four of them.

Egoistic bias

The egoistic bias leads us to focus on the wrong question. Instead of asking ourselves if A is better than Z, we tend to ask which of the two worlds we would personally ‌prefer to live in. If you were any of the (fewer) people living in A, you'd be having a much better time than if you were any of the (many) people living in Z (W_A is 500 times larger than W_Z), so the answer to the second question is obviously A. But this is totally irrelevant when answering the first question.

Tännsjö (2002, p.3) proposes a clever workaround. In order to choose impartially in which of the two worlds to live, we have to perform a Rawlsian thought experiment. Would A continue to be more appealing than Z behind a veil of ignorance? If our own existence were at stake, probably not.

In our example, N_Z is 1000 times larger than N_A, so the probability of any person chosen at random among the population of Z to exist in A is 0.001. That means that our choice is not between W_A and W_Z, but between W_A with probability 0.001 and W_Z with certainty. The expected value of choosing to live in A is thus 0.1, while the expected value of choosing to live in B is 0.2. A rational agent would thus prefer B.

Scope insensitivity

Scope insensitivity undermines our ability to have reliable intuitions regarding large quantities. When facing the choice between A and Z, the number of lives that would exist has very little, if any, effect on the value we intuitively attach to each world.

Imagine population A—all ten billion of them. Now imagine the ten trillion people making up population Z. Perhaps you have successfully imagined a larger quantity of people. But was it a thousand times larger? Our limited cognitive capacities do not allow us to picture precisely such enormous numbers of people, much less to sympathize with all of them. As a result, while W_A and W_Z intuitively seem drastically different, N_A and N_Z do not. A, therefore, intuitively seems far more attractive than Z.

Compounding tiny quantities

We also struggle with compounding tiny quantities. We neglect small numbers, forgetting that they can become very large when compounded several times. This may explain the unintuitiveness of the thought that a sufficiently high number of low-utility lives has a greater value than a smaller number of high-utility ones.

How can we avoid both ‌issues? By shutting up and multiplying, of course.

What life counts as “barely worth living”?

We tend to underrate the quality of lives barely worth living. According to Tännsjö (2002, p.5-6), our highly selective memory has a tight grip on the few blissful moments we experience, but it easily lets go of all the time spent below the threshold above which our lives are worth living. This leads us to overestimate the utility of our own life, which in turn makes us think that a life barely worth living must be a terrible one.

But, if Tännsjö is right, a life barely worth living is not so different from the typical life led by a citizen of an affluent Western country. He claims that

if only our basic needs are satisfied, then most of us are capable of living lives that, on balance, are worth experiencing. However, no matter how ‘lucky’ we are, how many ‘gadgets’ we happen to possess, we rarely reach beyond this level.

Thus, Z does not look "like a vast concentration camp". Instead, it contains lives quite like ours, and much better than the lives of people who are dying from painful diseases or those of non-human animals in factory farms.

Conclusion

The argument that our intuition deludes us does not prove that Z is better than A. Our biases and cognitive limitations may be simply enhancing the repugnance of a false conclusion. It suggests, however, that we should at least question our intuitions. 

Our brains did not evolve to deal with gigantic or minuscule numbers, let alone their products. Furthermore, we might focus on the wrong question, namely whether we would personally prefer to live barely worth living lives or blissful ones. Or we might even mistake "barely worth living" for "terrible". 

Once we acknowledge the unreliability of our intuitions when considering the repugnant conclusion, its repugnance seems at least doubtful. Let’s now move on to the second argument.

Avoiding the repugnant conclusion is problematic

Tännsjö (2002, p.16) makes a very strong claim. Not only is the avoidance of the repugnant conclusion not, pace Parfit, a desideratum of any plausible moral theory, but it is a red flag. Since the repugnant conclusion follows from plausible moral principles, we must be suspicious of any theory that does not lead to it. In explaining this position, I will follow the Benign Addition Argument offered by Huemer (2008, p.901). 

The repugnant conclusion follows from plausible principles

Consider the following principles, which assume that we are comparing worlds with respect to utility alone.

The Benign Addition Principle: If worlds X and Y are so related that X would result from increasing the well-being of everyone in Y by some amount and adding some new people with worthwhile lives, then X is better than Y.

Non-anti-egalitarianism: If X and Y have the same population, but X has a higher average utility, a higher total utility, and a more equal distribution of utility than Y, then X is better than Y.

Transitivity: If X is better than Y and Y is better than Z, then X is better than Z.

These three premises, taken together, necessarily lead to the repugnant conclusion, so the only way to avoid it is to reject at least one of them.

To show this, we can go back to our original example and add a third hypothetical world: A⁺. This world contains the same ten billion people of A, but with a slightly greater well-being level of 101, and another 9.99 trillion new people with a well-being level of 0.05. Let us also suppose that the population of A⁺ and Z is the same, although with different well-being levels.

By the Benign Addition Principle, A⁺ is clearly better than A, since it can be obtained by increasing the well-being of everyone in A by 1 and adding some new people with slightly worthwhile lives. By Non-anti-egalitarianism, Z is better than A⁺, since they have the same population, but Z has a higher average utility, a higher total utility, and a more equal distribution of utility. This is true because the average well-being level of A⁺ is roughly 0.15, while W_Z is 0.2. By Transitivity, given that Z is better than A⁺ and A⁺ is better than A, we arrive at the repugnant conclusion that Z is better than A.

What happens if we reject those principles

Intuitively, the Benign Addition Principle, Non-anti-egalitarianism, and Transitivity seem very reasonable. Can we safely reject any of them?

In the case of Transitivity, it seems implausible. By rejecting it, we would justify cyclical preferences. That is, preferring A to B, B to C, and C to A. But if you have such preferences, then one can easily pump money out of you by offering, for a small price for each transaction, to give you C in exchange for A, then B in exchange for C, then A in exchange for B, and so on indefinitely. Such preferences are thus irrational.

What about rejecting Non-anti-egalitarianism? It seems safe to assume that increasing total and average utility is a good thing. Therefore, the only way for Non-anti-egalitarianism to be false is for equality in the distribution of utility to be intrinsically bad. I doubt ‌anyone is willing to accept such an implication.

Finally, let’s consider the Benign Addition Principle. If A⁺ is the result of increasing the well-being of everyone in A by some amount and adding some new people with worthwhile lives, then A⁺ Pareto dominates A. Every single person prefers his or her existence in A⁺ to his or her existence or non-existence in A. It thus seems hard to argue that, contrary to the opinion of every single person involved, A is better than A⁺.

Conclusion

Any population axiology that avoids the repugnant conclusion rejects at least one principle between the Benign Addition Principle, Non-anti-egalitarianism, and Transitivity. Of course, this argument does not conclusively prove that Z is better than A. By pointing out this trade-off, however, it makes a strong case against the repugnance, understood as obvious falsehood, of such a claim.

As Zuber et al. (2021) claimed, it is not necessary for an adequate population axiology to avoid the repugnant conclusion. To reject the total view, therefore, it is not sufficient to show that it entails the repugnant conclusion.

Acknowledgments

Thanks to Justis Mills, Lorenzo Buonanno, and Adam Elwood for helpful comments and feedback.

References

Huemer, M. (2008). In Defence of Repugnance, Mind 117.468: 899–933.

Parfit, D. (1984). Reasons and Persons, Oxford: Clarendon Press.

Tännsjö, T. (2002). Why We Ought to Accept the Repugnant Conclusion, Utilitas, 14.3: 339–59.

Zuber, S., Venkatesh, N., Tännsjö, T., Tarsney, C., Stefánsson, H., Steele, K., . . . Asheim, G. (2021). What Should We Agree on about the Repugnant Conclusion? Utilitas, 33(4): 379-383.