Glad you’re fleshing this out and pushing the community to take variety/diversity more seriously as part of population axiology. I’ve had similar thoughts in this direction, and I think the core intuition is very compelling.

Caveat that I’ve only skimmed maybe a quarter of the full post so far, and I can already see that it goes well beyond the simple claim that “variety matters”: it adds a lot of context, formal structure, and specific assumptions/conditions. So I’m not trying to say this isn’t a much needed contribution.

My reaction is more about framing. I worry that the “new theory” framing + all the new words may make the central intuition feel more novel or exotic than it is. Many people, including/especially many who would not identify as utilitarians or EAs, already have the intuition that the value of a world depends not only on total welfare, but also on the diversity, richness, or non-redundancy of the lives/experiences it contains — roughly, that additional near-duplicate lives have diminishing marginal value.

So I’d find it helpful to separate, as clearly as possible, the widely shared motivating intuition from the more specific Saturationist implementation. Otherwise I worry the jargon makes the view feel more alien or proprietary than it needs to be, when the underlying motivation may actually be quite intuitive to many people. 

I haven't done philosophy in a while, might be missing something, but wanted to highlight what I think is the strongest objections to the view^[1] in a way that may be more salient than the framing in section 6. It's probably a reason why many might prefer a total view.

To be clear, I do think the Saturation View improves on other non-total views I know of, and I appreciate that they flag some of its hard-to-stomach implications. But I still think the post understates how bad the separability issue is. So here are two short points:

Non-separability is really bad.

The core problem is that facts about/experiences of wholly unaffected people can change the value of the affected person's experiences. If there are already sufficiently many people elsewhere with sufficiently similar experiences, then an additional person having an extremely deep, meaningful, happy life adds near-zero marginal value. That seems very hard to accept.

And for negative experiences the implication is potentially even less intuitive. An additional torturous experience can add almost no marginal disvalue if enough sufficiently similar torture already exists. They discuss this under the “cheap suffering” problem & call it the strongest argument against the view, but I think it is worth emphasizing just how unintuitive of a conclusion this is. From the victim’s perspective, the torture is not any less bad because other similar torture already occurred. But the saturation view says that, from the point of view of population value, their torturous experience would matter hardyl at all.

ETA: Relatedly, the view assigns value to our experiences depending on empirically inaccessible facts. Whether sufficiently distant aliens have sufficiently similar experiences is something we probably can't know, but it would radically change how our actions matter. That seems strange.

I don't think the 'tameness' of the view recovers that much?

My understanding is that the Saturation View does better because violations of separability are localized. Ancient Egyptians or distant aliens only affect the marginal value of new lives if their experiences are sufficiently similar. So in many "normal situations", the view behaves roughly separably.

But the separability worry still holds with sufficiently large numbers. If enough sufficiently similar unaffected lives exist elsewhere, they can radically change the marginal value of what we do here.

And population ethics is full of large-number objections. The Repugnant Conclusion itself gets its core intuitive force from considering sufficiently enormous populations, and is also not a “normal situation.” So if the Saturation View is partly motivated by avoiding the very bad large-number implications of total views, then its own large-number implications seem fair game too.

1. ^{^}

   the authors agree with this, afaict

I haven't yet got past the 1.4. Arguments for Value of Variety section because I'm just a bit unconvinced.

You could reword the intuition pump section like this:

Imagine some truly terrible moment — say extreme torture. Suppose that this torture is far more terrible than anything that humanity has experienced to date: you or I would give up years of ordinary happy life just to avoid such a peak of despair. But now suppose that this torture is just ever so slightly less bad than some other torture approach that is the worst thing that could conceivably be produced, with the same resources. For example, a radically different device is used which leads to an experience that is ever so slightly more painful. 

What is better? The worst possible torture alternating with the slightly less bad torture? Or just the slightly less bad torture for the rest of time?

I suppose I can imagine someone saying the former, but I wouldn't. I just want less suffering! You can dismiss this rewrite by saying variety is only good if it's variety of good things, but this would introduce an asymmetry and I'm unsure that is justified. I feel like people say they like variety because we have repeatedly experienced it to be pleasurable, and that introduces a bias that we struggle to avoid when we are asked to judge scenarios that aren't different in terms of welfare. For the same reason I'm a little unconvinced by the intrapersonal variety argument.

On the realisation-value argument. I don't really think there is intrinsic value of things being realized. If in the distant arctic some polar bear walks a route that no polar bear has walked before but which is the exact same in every welfare-relevant way, I just don't really care. Which is another way of me saying, realizing new things can indeed be great, but only when we can enjoy them for being new.

On the benefits for axiology point. This doesn't so much seem an argument for variety as it seems a direct argument for the saturation view. If the saturation view allows us to avoid lots of other unpalatable conclusions then it may be worth adopting for that alone!

Quick take:

I disagree with the intuition that diversity is intrinsically valuable (Variety > Homogeneity). I think this intuition is merely a psychological illusion driven by a failure to truly accept the definitions of the thought experiment.

When we imagine living in a homogeneous world, we intuit that we would enjoy it less (due to boredom, lack of novelty, etc.)—meaning our individual well-being would suffer. But that just means diversity is a preference within our individual utility functions, not an intrinsic part of the axiology.

The thought experiment tricks us because we fail to truly hold "all other things being equal." If we are explicitly told that the welfare levels in Homogeneity are greater than or equal to those in Variety, then those welfare figures already account for any negative effect caused by a lack of diversity. Once you strictly hold welfare constant, the intuition that Variety > Homogeneity evaporates. Diversity is likely just an instrumental good for the welfare of individuals, not an intrinsic axiological metric.

Our intuition tricks us into double-counting diversity: we treat it as an intrinsic axiological value when it is actually just an instrumental preference within an individual's utility function. If the individuals in a "monoculture" are perfectly content with that homogeneity, there is no real contradiction in concluding that Homogeneity > Variety.

The Saturation View confuses me: it seems highly contingent on the idea that most societies have reached diminishing marginal returns per additional person for utility, for which I would assume otherwise. How would attributing intrinsic value to diversity be more valuable than total utilitarianism when a society has not hit diminishing returns?

Related: Sublinear Utility in Population and other Uncommon Utilitarianism by Alice Blair

A different objection:

• Low-welfare confinement: Barely-positive-welfare value-bearers occupy a small enough region of the landscape, or are sparse enough and illuminate only a small enough neighbourhood around them, or both, such that the total value that can be contributed by barely-positive-welfare value-bearers is strictly smaller than the total value that can be contributed by more-than-barely-positive-welfare value-bearers.

This kind of statement seems like philosophical wishful thinking: it makes an arbitrary assumption about what is possible in order to avoid an uncomfortable conclusion about what is preferable (the Repugnant Conclusion). It simply asserts without justification that the space of low-welfare variety is small.

This isn't just an innocent modeling choice, nor is it an axiom of the Saturationism axiology itself; it's a substantive claim about reality inserted to make the axiology work. By stipulating that low-welfare value-bearers occupy a confined region of the conceptual landscape, we are forcing a physical constraint onto the universe without providing any physical or empirical justification for it.

Why should we accept this asymmetry? It seems equally plausible that barely-positive-welfare lives could manifest in a greater diversity of configurations than high-welfare lives. Without a robust justification for why the low-welfare landscape is uniquely restricted, this constraint just looks like an ad hoc mathematical patch to save the axiology from the Repugnant Conclusion.