We have a sense of how good things could be. We're probably born with some genetically informed priors, but mostly we develop this sense based on experience. When a good thing happens to us our sense of what's possible goes up, as when we observe good things happening to others. If you think of something as inaccessible to you, it doesn't affect your sense of how good things could be. Happiness is having how things are going be closer to how you think things could be going.

Some things this model predicts:

• The absolute level of how good things are doesn't matter very much. A world where the cocoa tree hadn't happened to evolve would be similarly happy to the current world.

• Switching from something worse to something better makes you happier, though you mostly adapt and end up not that much happier than before. Inventing something new that's as good as chocolate would be positive for current people.

• Switching from something better to something worse makes you less happy, and you mostly don't adapt and end up a bunch less happy than before. Cocoa tree extinction would be very bad for current people.

• Inequality is bad. A world where a rich people eat chocolate is worse than one where chocolate is evenly distributed or isn't a thing.

• Social mobility is bad. People moving down are more sad than people moving up are happy. The idea that you could move up makes the good things rich people have feel more accessible than if class/caste boundaries are immutable, and so makes inequality more painful.

• Raising standards smoothly gives the most happiness. Start as a child in material poverty, though with good nutrition, good education, and everything else you really need. Then add more and more comforts as you get older. Don't try to equalize consumption over your lifetime.

(This has some resemblance to how positional goods work, but isn't the same. For example, if the cocoa tree goes extinct only a small fraction of people have their relative positions change, but lots of people are worse off.)

I'm not sure how much I buy this model, though I've been thinking along these lines for a while. Either way, I definitely don't currently act as if I believe its consequences in their entirety. For example, I like to give my kids things they will enjoy, and this isn't a factor I've been taking into account in thinking about global poverty charities.

(Thanks to David Chudzicki for conversations inspiring this post.)