Three Worlds Collide by Eliezer Yudkowsky
My rating: 5 of 5 stars
This short story describes a spaceship of humans in the future who make first contact with not one, but two intelligent alien races. The result involves spirited debate as each of the three realize they all have very different views on which moral facts are true.
If you have a group of friends interested in metaethics, I strongly recommend you try printing out hard copies of this short story in sections, and read the story together in person. Each successive section will give you a lot to talk about, and there are few enough sections of short lengths that it will only take around 2.5 hours to read through every section with plenty of conversation between each.
Those not as interested in metaethics will still get something out of the story, though they might not rate it as highly as I have.
View all my reviews