There are two reasons why necromancy is commonly thought to be evil.
Raising an army of any sort to terrorize the countryside is considered a pretty evil act.
To raise the undead is to desecrate their corpse and grave. This could also include transgressions against any religious institutions ...
I don't want to start an ethical debate but I think this question is linked with nowadays organ donor debate. I think it really more accepted now than it was some decades ago. So maybe with the time, you would be proud of your dearly departed loved one building an orphan !
@EngelOfChipolata: Imagine an entrepreneur forcing unwilling, unpaid slaves, perhaps from another country or ethnic origin, to work in order to build an orphanage or a hospital. Don't you think the entrepreneur would be considered evil?
The key in organ donors is the "donors" part. As in, voluntary. There was a Monty Python's sketch about surgeons collecting organs before the donor was dead - funny on TV, but I'm sure it will be considered "evil" if you tried that in real life. If you are gonna raise my mother's corpse to do anything at least ask me first or I'm going to get very angry.
@Rekesoft You are right of course ! The comparison was just a try to avoid thinking about death in a too religious way (which may make no sense in OP world).
@EngelOfChipolata The OP was asking about why necromancers are commonly considered evil. As far as I know he is asking about prior art not his personal setting.
@EngelOfChipolata I don't think this is just a religious matter. Death makes humans uncomfortable, and thus we like to "respect" the remains of other dead humans, simply because the idea that our remains are going to be "used" in some strange way makes us feel even more uncomfortable about it. Other than that it obviously doesn't make much sense, those remains will become dust sooner or later.
@EngelOfChipolata The term you're looking for is "orphanage". An "orphan" is a person with no parents. An "orphanage" is where an orphan lives. I would certainly hope that the skeletons aren't building new children with spare flesh here and there.
@EngelOfChipolata If you either remove "orphanage" from the equation, or undead from the equation, it becomes evident. The real issue is involuntary servitude. Plus, the obvious consequences would be that necromancers would become the sole source of labor, as undead would work for free. Then of course, when and if undead came to be in short supply, the natural course of action would be to create more dead to animate through murder, war and other means.
What about if the people aren't recognizable? Like they're skeletons? It would be easy to put a restriction on the state of the body when it's animated, and that should help deal with sentimental problems.
@RichardU "the obvious consequences would be that necromancers would become the sole source of labor, as undead would work for free." Robots work for free too, yet manual laborers haven't been completely replaced by robots. Making enough undead isn't necessarily cheap for the necromancers, and as you point out there are limits on the supply of corpses as well.
Not for full answer, so i leave just comment: Long time ago i read (fantasy ;) ) book about desert nation with so few resources that each person at 25th birthday make suicide and was bring back as... not zombie exactly, but something like zombie haunted by original soul. They had to consume magic, but not food and they was just "living" as happy as before. The book was about some "dark" necromancers who wanted to know how they can create so flawless undead (and the secret was that they did it voluntarily & no-one even try to control them). Whole nation was ok with necromancy.
@JAB If something can build a house, it can probably drop a few bricks on people.
@Jan'splite'K. If you can't remember which book it was, you could ask a story identification question on Science Fiction & Fantasy. (If you do so, please drop me a link!) If you can remember, could you mention which book it was? It seems quite interesting; perhaps there are some other concepts in there that could be s̶t̶o̶l̶e̶n̶ borrowed.
Discussion on answer by sphennings: C…
Discussion on answer by sphennings: C…