(Inspired by Eliezer's essays on designing utopias.)

I was recently talking to a friend about what key features society would need for people to be happy throughout arbitrarily-long lives - in other words, what would a utopia for immortals look like? He said that it would require continual novelty. But I think that by itself, novelty is under-specified. Almost every game of Go ever played is novel and unique, but eventually playing Go would get boring. Then you could try chess, I suppose - but at a certain point the whole concept of board games would become tiresome. I don't think bouncing around between many types of different activities would be much better, in the long run. Rather, the sort of novelty that's most desirable is a change of perspective, such that you find meaning in things you didn't appreciate before. That interpretation of novelty is actually fairly similar to my answer; I said that the most important requirement is a feeling of progress. By this I mean:

• Your past isn't being lost as it recedes from you.
• Your future will be better than your past - in qualitative ways as well as quantitative.
• You receive increasing social recognition for your achievements.
• You feel like you are continually growing as a person.

Some of these criteria are amenable to technical solutions - for example, memory enhancements would be very helpful for the first. But simply abiding by the basic principles of liberalism makes others very difficult to universalise. As long as we allow people to make their own choices, there will be some people who end up falling into addiction, or lethargy, or self-destructive spirals. We could theoretically make this rarer by having stronger social or legal norms, so that people still have freedom, but not total freedom. We could also make the consequences of failure less unpleasant (e.g. with welfare systems) and less permanent (e.g. by eradicating the most addictive drugs). Yet even then, the social repercussions of being unsuccessful would still weigh on people heavily - man does not live by bread alone, but by the status judgements of his peers.

Fortunately, perceived social status is not zero-sum, because different subcultures value different things. That helps many more people receive social recognition for their achievements; ideally everyone would find a Dunbar-sized community in which they can distinguish themselves. Sure, some will be envious of other communities, but I think abstract concerns like those would mostly be outweighed by their tangible activities and relationships. For example (although I don't have good data on this) anecdotally it seems that modern homeless communities can often be tighter-knit and more supportive than well-off suburbs.

But splintering society into fragments doesn't solve the question of what the overarching cultural framework should look like - and we do need one. Firstly because subcultures usually need something to define themselves in opposition to; also because moving between subcultures would be much more difficult if they didn't share fundamental tenets. Yet now we're back to the problem of what general society should prize and reward in order for almost everyone to feel like their lives are valuable and progressing towards even more value.

Here's a slightly unusual solution, which embraces Eliezer's recommendation that utopias should be weird: we should strictly stratify society by age. This doesn't mean that people of different ages must isolate themselves from each other (although some will), but rather that:

• Older people are respected greatly simply by virtue of their age.
• Access to some prestigious communities or social groups is age-restricted.
• There are strong norms (or even rules?) about which types of activities one should do at a given age.

Age hierarchies are not a new idea; they've been the norm throughout human history, and were only relatively recently discarded from western culture. Granted, that was for good reasons, like the fact that they tend to hold back social and technological progress. But our challenge here is to come up with a steady-state culture which can provide lasting happiness, not one which maximises speedy progress. Age hierarchies are the one sort of hierarchy in which everyone gets to advance arbitrarily far upwards. They also tap into fundamental aspects of human motivation. Video games are addictive because you can keep unlocking new content or "levelling up". But they're also frustrating because that progress isn't grounded in anything except a counter on the screen. Games like Starcraft and League of Legends instead provide satisfaction through victory over others - but that's zero-sum, which we don't want. The third class of games which people spend most time on - MMORPGs such as World of Warcraft or EVE - augment the experience of gaining resources and levelling up with a community in which high-achieving players are respected. In a long-lived society with age hierarchies, people could always look forward to "unlocking new content" based on their age. Even people who aren't very high-status within their own age group could find respect amongst younger groups; and as long as people continued having children, your relative status in society would always increase.

Note that this doesn't imply that children and young adults would have bad lives. Firstly, despite being respected the least, they also experience the greatest sense of novelty and opportunity. Even if they feel like they're missing out on some opportunities, they can be consoled by the thought that their time will come. And they probably won't be very upset about "missing out" anyway - the experiences which older people prize highly are often not those which young people envy. Teens don't feel like their lives are worse because they don't yet have children and go to nightclubs not cocktail parties. Champagne-sipping parents, on the other hand, usually think their lives have become deeper and richer since their teenage years; neither side is unhappy with their lot. A more speculative example which comes to mind is the traditional progression through stages of enlightenment in Buddhism, where you simply don't understand what you're missing out on until you're no longer missing it. To take this to an extreme, access to the next stage of society could depend on learning a new language or framework of knowledge, in which you can discuss ideas you couldn't even conceptualise before.

Stepping back from the weirder implementations, how might longevity impact close relationships? There's a story I remember reading about a world in which people live arbitrarily long; every few decades, though, they simply leave their entire social circle, move away, and start afresh. This seems like a reasonable way to keep a sense of excitement and novelty alive. However, my friend argues that if you live for a very long time, and become close to many people, then you'll eventually stop thinking of them as unique, valuable individuals. I do think that there are enough possible ways to have relationships, and enough variation between people, to last many, many lifetimes, so that you can continually be surprised and grateful, and develop as a person. But I concede that left to themselves, people wouldn't necessarily seek out this variety - they might just decide on a type, and stick to it. I think that age stratification helps solve this problem too. Perhaps there can be expectations for how to conduct relationships based on your age bracket: at some points cultivating a few deep friendships, at others being a social butterfly; sometimes monogamous, sometimes polyamorous; sometimes dating people similar to you, sometimes people totally different; sometimes staying within your age group, and sometimes spending time with people who are much older or younger and have totally different perspectives. In our world, people would shirk from this - but I imagine that a very long-lived society would have a culture more open to trying new things.

Lastly, we should remember that the dark side of having strong social norms is enforcement of those norms. To some extent this can be avoided by creating a mythos which people buy into. Cultural narratives affect people on such a deep level that many never question the core tenets (like, in the west, the value of individualism). It would also help if there were separate communities which people could join as an act of rebellion, instead of wreaking havoc in their original one. But in general, creating norms such that even people who challenge those norms do so in non-destructive ways seems like a very difficult problem. We're basically trying to find stable, low-entropy configurations for a chaotic system (as opposed to stable high-entropy configurations, such as total collapse). Even worse, the system is self-referential - individuals within it can reason about the system as a whole, and some will then try to subvert it. There's much more which needs to be figured out, including entirely new fields of research - but nobody ever said designing a utopia would be easy.