* FridgeLogic:
** The reason that in the beginning, female characters couldn't become Diagnosticians. The in-series justification given by O'Mara early on is that females are more aggressive when it comes to mental defense than males. While male characters suffer a lot of discomfort from educator tapes imposing foreign feelings and thoughts on them, females will generally automatically destroy an educator-tape imposed personality that tries to tamper with them like that. [[FridgeLogic Given the series' rules about psychic abilities]], it makes sense for a species with latent psychic abilities that carries young to be able to ensure they don't take over or influence the parent's body (see the Protectors of the Unborn). This tallies with Conway's experiences with psychic contact, which generally (especially early on) consist of sudden infodumps that he doesn't have a lot of control over, while a female physician in another book is much more in control of her own psychic contact.
** Bearing this out, while female educator tapes were taken, they're deemed unsafe by O'Mara [[spoiler:and he would know.]] You have to wonder how much of O'Mara's not-exactly-romance plot is caused by the fact he's a JerkWithAHeartOfGold and how much is caused by [[spoiler:letting a desperately unhappy personality that's ''much'' better at psychic warfare than he is into his head and being unable to get himself to remove it, even though he should know that's the safe and sane thing to do.]] The FridgeHorror turns a touching storyline into NightmareFuel.
** Murchison later becoming a pathologist can be explained by TechnologyMarchesOn - the educator tape system has been improved and it's harder for a host's defenses to force out the foreign personality. While it doesn't say that she started using educator tapes, the attempted appendectomy in one of the books shows how important educator tapes are to interspecies medicine, and even if pathology doesn't involve living patients, it's still diagnosis and a physician without an educator tape would miss things that one with an educator tape would see. Since Sector General wouldn't stand for that kind of oversight, unless she can host educator tapes for at least short periods, it's doubtful she would ever have gotten the post, despite her experience and connections.
** James White never entirely got over the sexism he wrote into early stories in the series. He had alien characters of multiple species who are identified as female use the educator tapes; along with the many alien characters whose genders are unspecified who also use them. But he never made the obvious retcon to explicitly have human characters use the tapes regardless of gender. And he never let women become Diagnosticians, even though Murchison got to do pathology.
* InferredHolocaust - The Galaxy is peaceful and utopian because the only species moving around are the ones that grew past war and achieved the unity required to go stably interstellar. This may mean that the rest are still maturing, or it may not. Earth-humans and Orligians, the first sentient species that Earth-humans made contact with, actually fought a war shortly after their FirstContact. They're both very embarrassed about it.
** The Etlan Empire averts that pattern; being organized under an oppressive government that deliberately infected the entire population of a planet with various diseases as a way to get continued support from the rest of the empire. When the Federation arrives and starts curing the diseases, the Etlan government lies to the public and its soldiers about that and declares war on the Federation - only stopping when Conway treats a group of captured Etlans that happens to include one of the senior commanders of the fleet sent to attack the hospital.
** For a different inferred holocaust: We never learn many details of events on Earth between the present / when White wrote the series and when first contact with aliens happened, except that there were some generation ships launched. But all but a couple of the named human characters in the Sector General series have names that would be typical for white UK / Ireland residents in the mid-to-late 1900s, less but still somewhat likely in some other places like the US / Canada / Australia, and not at all likely elsewhere. What happened to most of humanity?

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