Aaaaaaaaaaaaargh! Sooooo goooooood!
When I learned that Le Guin's father was an anthropologist it explained a huge amount to me. Her SF "what ifs" aren't much along the lines of "what if there was magic goo that could make and fix everything?" or "what if aliens built an interstellar subway system then disappeared?" They are more along the lines of, "what if the female:male ration was 1:16 instead of 1:1?" or "what if most people were bi-sexual, with a minority of heterosexuals?" or "what would the religion of people on a generation ship be like?" or "what if everybody was an introvert?" Not much about technology, a lot about society.
All of these stories are excellent. In my experience it's unusual for the standard of a short collection to be so uniform (and high).
Serious spoilers for one story ahead.
The one that I want to discuss is the novella, Paradises Lost. It's a generation ship tale, putting it square in the mainstream of SF and inviting comparison with all the other such tales there have been over the decades. Earth's major religions are represented upon launch but five generations in, they have faded away, shorn of their context and therefore relevance and supporting societies. However, a new religion arises that threatens the mission, because it suggests that only the ship is real and it's Heaven.
Le Guin seems to be saying that religion is an invention that en mass humans can't do without and that it fulfills some kind of psychological need to explain and make bearable one's circumstances - and that just as inevitably people will opportunistically use it to try to gain power over others.
In Le Guin's made up situation, the fictional religion gives greater meaning to the lives of people who's function is merely to produce the next generation and keep them alive for an event they will either be too old or too dead to fully participate in themselves (arrival at the Destination). That meaning is that the journey is the genuinely important thing and actually arrival is undesirable.
To have validity, this theory must apply to real religions. I can figure it out with regard to Christianity. It's the religion of the poor and oppressed: never mind your poverty and powerlessness in this life, in the next, eternal one, you will be rewarded with endless bliss in Heaven while your rich oppressors are eternally punished in Hell. The pantheistic "spirit of place" religions such as that of the pagan Celts or of Japanese Shinto also make sense in the contexts in which they arose - an apparently incomprehensible and capricious world. Every place, every thing and every type of thing must have a controlling spirit that, whilst wilful and unpredictable can at least be negotiated with - here's my offering, please don't harm me. It seems less obvious to me regarding other religions, which might just be a reflection of my lack of knowledge. Why did Islam deviate from Christianity? What changed circumstance or new need did it satisfy? I don't know. But, to come full circle, this theory seems a very anthropological one.
Great stories - read them.