Problems in population ethics (are 2 lives at 2 utility better than 1 life at 3 utility?) are similar to problems about lifespan of a single person (is it better to live 2 years with 2 utility per year than 1 year with 3 utility per year?)
This correspondence is formalised in the “Live Every Life Once” principle, which states that a social planner should make decisions as if they face the concatenation of every individual’s life in sequence.[1] So, roughly speaking, the “goodness” of a social outcome s, in which individuals face the personal outcomes p1,…,pn, is the “desirability” of the single personal outcome p1▹⋯▹pn. (Here, p1▹p2 denotes the concatenation of personal outcomes p1 and p2.)
The LELO principle endorses somewhat different choices than total utilitarianism or average utilitarianism.
Here’s three examples (two you mention):
(1) Novelty
As you mention, it values novelty where the utilitarian principles don’t. This is because self-interested humans value novelty in their own life.
Thirdly, [Monoidal Rationality of Personal Utility][2] rules out path-dependent values.
Informally, whether I value a future p more than a future q must be independent of my past experiences. But this is an unrealistic assumption about human values, as illustrated in the following examples. If p denotes reading Moby Dick and q denotes reading Oliver Twist, then humans seem to value p▹p less than p▹q but value q▹p more than q▹q. This is because humans value reading a book higher if they haven’t already read it, due to an inherent value for novelty in reading material.
In other words, if the self-interested human’s personal utility function places inherent value on intertemporal heterogeneity of some variable (e.g. reading material), then the social utility function that LELO exhibits will place an inherent value on the interpersonal heterogeneity of the same variable. Hence, it’s better if Alice and Bob read different books than the same book.
(2) Tradition
Note also that the opposite effect also occurs:
Alternatively, if p and q denote being married to two different people, then humans seem to value p▹p more than p▹q but value q▹p less than q▹q. This is because humans value being married to someone for a decade higher if they’ve already been married to them, due to an inherent value for consistency in relationships.
— ibid.
That is, if the personal utility function places inherent value on intertemporal homogeneity of some variable (e.g. religious practice), then the social utility function that LELO exhibits will place an inherent value on the interpersonal homogeneity of the same variable. Hence, it’s better if Alice and Bob practice the same religion than different ones. So LELO can account valuing both diversity and tradition, whereas total/average utilitarianism can’t do either.
(3) Compromise on repugnant conclusion
You say “On the surface, this analogy seems to favor total utilitarianism.” I think that’s mostly right. LELO’s response to the Repugnant Conclusion is somewhere between total and average utilitarianism, leaning to the former.
Formally, when comparing a population of n individuals with personal utilities p1,…,pn to an alternative population of m individuals with utilities q1,…,qm, LELO ranks the first population as better if and only if a self-interested human would prefer to live the combined lifespan p1▹⋯▹pn over q1▹⋯▹qm. Do people generally prefer a longer life with moderate quality, or a shorter but sublimely happy existence? Most people’s preferences likely lie somewhere in between the extremes. This is is because personal utility of a concatenation of personal outcomes is not precisely the sum of the personal utilities of the outcomes being concatenated.
Hence, LELO endorses a compromise between total and average utilitarianism, better reflecting our normative intuitions. While not decisive, it is a mark in favour of aggregative principles as a basis for population ethics.
MRPU is a condition that states that the personal utility function of a self-interested human v:P→R satisfies the axiom v(p1▹p2)=v(p1)+v(p2), which is necessary for LELO to be mathematically equivalent to total utilitarianism.
Yeah. I decided sometime ago that total utilitarianism is in some sense more “right” than average utilitarianism, because of some variations on the Sleeping Beauty problem. Now it seems the right next step is taking total utilitarianism and adding corrections for variety / consistency / other such things.
That’s a neat and straightforward way to combine average and total utilitarian approaches. This still doesn’t sound quite right to me, LELO seems to be somewhat like 2⁄3 total and 1⁄3 average, while for my intuition, the opposite ratio seems to be more preferable, but its definetely an interesting direction to explore.
This correspondence is formalised in the “Live Every Life Once” principle, which states that a social planner should make decisions as if they face the concatenation of every individual’s life in sequence.[1] So, roughly speaking, the “goodness” of a social outcome s, in which individuals face the personal outcomes p1,…,pn, is the “desirability” of the single personal outcome p1▹⋯▹pn. (Here, p1▹p2 denotes the concatenation of personal outcomes p1 and p2.)
The LELO principle endorses somewhat different choices than total utilitarianism or average utilitarianism.
Here’s three examples (two you mention):
(1) Novelty
As you mention, it values novelty where the utilitarian principles don’t. This is because self-interested humans value novelty in their own life.
In other words, if the self-interested human’s personal utility function places inherent value on intertemporal heterogeneity of some variable (e.g. reading material), then the social utility function that LELO exhibits will place an inherent value on the interpersonal heterogeneity of the same variable. Hence, it’s better if Alice and Bob read different books than the same book.
(2) Tradition
Note also that the opposite effect also occurs:
That is, if the personal utility function places inherent value on intertemporal homogeneity of some variable (e.g. religious practice), then the social utility function that LELO exhibits will place an inherent value on the interpersonal homogeneity of the same variable. Hence, it’s better if Alice and Bob practice the same religion than different ones. So LELO can account valuing both diversity and tradition, whereas total/average utilitarianism can’t do either.
(3) Compromise on repugnant conclusion
You say “On the surface, this analogy seems to favor total utilitarianism.” I think that’s mostly right. LELO’s response to the Repugnant Conclusion is somewhere between total and average utilitarianism, leaning to the former.
See:
Myself (2024), “Aggregative Principles of Social Justice”
Loren Fryxell (2024), “XU”
MacAskill (2022), “What We Owe the Future”
MRPU is a condition that states that the personal utility function of a self-interested human v:P→R satisfies the axiom v(p1▹p2)=v(p1)+v(p2), which is necessary for LELO to be mathematically equivalent to total utilitarianism.
Yeah. I decided sometime ago that total utilitarianism is in some sense more “right” than average utilitarianism, because of some variations on the Sleeping Beauty problem. Now it seems the right next step is taking total utilitarianism and adding corrections for variety / consistency / other such things.
That’s a neat and straightforward way to combine average and total utilitarian approaches. This still doesn’t sound quite right to me, LELO seems to be somewhat like 2⁄3 total and 1⁄3 average, while for my intuition, the opposite ratio seems to be more preferable, but its definetely an interesting direction to explore.