Salazar Slytherin, one of the four Hogwarts founders, wanted to deny entry to students of mixed blood, and centuries later, his ideas still linger. The first time Harry meets Draco, Draco asks about Harry’s parentage and says, “I really don’t think they should let the other sort in, do you? They’re just not the same; they’ve never been brought up to know our ways…I think they should keep it in the old wizarding families” (Rowling, Philosopher’s Stone 61). All Slytherin characters begin with the assumption that pure-blood wizards have more talent, showing how far the stereotype has spread. Even the “good Slytherin” Horace Slughorn apes this attitude, as Harry considers him “much too surprised that a Muggle-born should make a good witch” (Rowling, Half Blood 74). These ideas reject evidence in favor of prejudice, employing ignorance and false science to support their claims. Still, there is a deeper issue here, as the Muggles persecuted wizards long ago. Now the two groups must learn to trust before the Wizarding World disintegrates completely.
The house-elves, however, are treated far worse than the Muggle-borns. Dobby gets death threats five times a day at the Malfoys, and a flogging for burning dinner. The greatest problem is in fact psychological: even an elf like Dobby who longs for freedom and betrays his hated masters, the Malfoys, at each opportunity, passively waits for clothing in order to be freed. He feels he is bound, thus he cannot escape. Even when he’s freed, the other elves regard him as a dangerous rebel. The problem is the house elves’ conditioning: they see it as their duty to love and protect their masters, and a betrayal to leave. After centuries of elf subordination, both masters and slaves believe this is the natural order, and perpetuate the unjust system. Only Hermione, an unindoctrinated bystander, can see elf-life for the vicious exploitation it truly is, and she devotes her life to changing it. This will take time: The Hogwarts elves view her as “mad and dangerous” and feel insulted by her gifts of clothes, showing how uncomfortable they feel outside their well-defined roles in the kitchen. Clearly, the damage that the wizards have caused for centuries won’t disappear overnight.
It’s no wonder goblins, merfolk, and centaurs remain hostile and apart: they have limited choices in the Wizarding World: brainwashed servitude like house elves or classification as dangerous monsters. The goblins have found in niche in the banking system where they work well, despite Bill’s warnings that they shouldn’t be trusted, thanks to all the bad blood and hostility between species. Werewolves, however, are forbidden work, pushing them toward criminal behavior. The merfolk and centaurs keep themselves apart, though they willingly help the kindly Dumbledore, who provides the exception to every racial rule. The greatest problem is the lack of governmental representation, allowing wizards unlimited exploitation.
Without an overwhelming change in perception, the false stereotypes and exploitation will continue indefinitely.