I think the case can be made that there are those who think wizarding traditions, culture, and probably even blood lines are important, but that not all of them are evil. Some of them object to Riddle’s violence, bloodshed, and/or cruelty even if they would support the pure-blood supremacy he nominally espouses. Of these people I think it would be well to remember that non-magical aristocracy had similar prejudices about bloodlines, giving English society a distinctly caste-like look and feel for centuries.
Inbreeding among the European aristocracy was prevalent enough that some recessive genetic conditions became problematic for them, most notably the clotting disorder that some of Europe’s royals carried. It is hardly surprising that the magical world would have adopted similar attitudes. If their lifespans are truly longer on average (Harry’s OWLs are administered by an examiner who also administered the NEWT exams for Professor Dumbledore 1), then their isolation would make it an even bigger and longer lasting problem that could easily persist to Harry’s time. I suspect that pure-blood is actually an over simplification of the average pure-blood’s world view. I suspect that Mrs. Rowling, being focused on school kids, simply did not expose us to the class structure that must have carried over from the non-magical world as the Statute of Secrecy gave a final divide to the two societies.
Thus while some may have been obsessive about blood, I’m going to bet the real reason the Crabbes or the Goyles are not part of the “Sacred Twenty-Eight” is that they are servants. It is not that I am ignoring or discounting Mrs. Rowling’s article on the origin and development of the idea of pure-blood and half-blood status. It is simply that while yes, I am an outsider looking in, I can see no way that any society based on English society in the late 1600s can not have a strong caste component to it. The counter balance would be that all of them go to Hogwarts, which forces a degree of social mixing that caste based societies rarely tolerate. That, combined with the overall lack of population, and doubtless a bias towards controlling magical power by marrying strong witches or wizards into the family regardless of status, would have created some degree of levelling, raising the lowest castes up some, reducing the aristocracy from untouchable lord-lings to something more like clan chiefs. But class consciousness was bred strongly into your average British person. So strongly that you see it consistently in all of their literature, be it Jane Austen (born 1775), Charles Dickens (born 1812), Arthur Conan Doyle (born 1859), Agatha Christie (born 1890), or Evelyn Waugh (born 1903). I could name others, but the selection above has authors with works published across the time-span to account from within a generation or at most two of the Statute of Secrecy through the publishing of the Sacred Twenty-Eight.
If you think about it, this would help make sense of what goes on as Riddle rises to power during the 1960s and 1970s. There are families like the Potters who are pure-bloods, but essentially by chance. I suspect they have historically been fairly class conscience, but not bought into the whole Slytherin blood status mess. However, in the magical world, most upper class girls would have come from other magical families, so more or less accidentally the Potters are mostly pure-bloods. The same is probably true of the Weasleys, Longbottoms, Abbotts, and any others who made up the minority who protested their inclusion on the Sacred Twenty-Eight list.
The Weasleys apparently became notorious for their protest, and incited a great deal of hatred. That hatred in a Renaissance, if not positively Medieval society, would have triggered feuding, and would explain their present state. The current Weasley family we know lives on a fairly good sized plot of land in a part of England where I am told land is fairly expensive, but the house on that land is cobbled together with a substantial portion of do-it-yourself construction and a whole lot of home grown magic. They have lost most of their wealth, including any hereditary home(s), but not all of the land that was once attached to that home. Arthur has a middling high, but not prominent, position in the ministry, and apparently has lots of connections and a fair amount of influence. This makes sense if you view them as impoverished aristocracy, a family who has lost a lot, but retains vestiges of their former influence and power.
Returning to my thoughts on Riddle’s rise to power, he polarises the entire society, and focuses the survivors of the first war on blood status in a way the generation just before Grindelwald and World War I did not care. Some authors call Riddle’s rise in the 1960s and 1970s the first war, but in a real sense it is the second war around blood status in two generations. Between the two dark lords, especially considering Riddle apparently killed off entire families and not just those who fought against him personally, those who resisted him are now few in number and, coming out of the two wars, no longer sufficient in number to be as class conscience as their grand parents might have been. Those who are most strongly traditional but opposed to violence might have survived Grindelwald, but Riddle would be a harsher reality. Any support for law and order at the expense of his power would be ruthlessly quashed, leaving on the “traditionalist” side only those who also believe Slytherin’s blood nonsense to at least some degree.
On top of the polarising effect of the wars, there is also two other affects working to associate class status with blood status. The idea of blood status was associated with Slytherin, and thus with Hogwarts’ Slytherin house. Students sorted into that house are those who show tendencies towards cunning and ambition. Heirs sorted into Slytherin will vocally espouse Slytherin’s philosophy as a matter of house pride. Their ambitious dorm mates will do so to curry favour with them, re-enforcing the beliefs. They will marry for money and power, re-enforcing these beliefs beyond school with social connections, and creating a feedback mechanism into the next generation.
Eventually there are too many of them for one house at Hogwarts. More than a quarter of the population strongly supports blood status. More than a quarter of the population is associated by marriage or fealty to the Wizengamot Lords who protect it in the government. Where will these children be sorted? Slytherin students despise Gryffindor’s house. The son or daughter of a Slytherin family, their allies or dependants cannot afford to be sorted into Gryffindor. The family members risk being disowned as traitors. The allies and dependants risk being cut off and isolated. They cannot go to Gryffindor.
Hufflepuff house is famous for taking everyone. While it is the house of hard work and loyalty, the Sorting Hat tells us that Hufflepuff said “I’ll teach the lot, and treat them just the same.”2 It is safe to say that Hufflepuff house has always had a disproportionate number of the school’s first generation and second generation students. A student who is essentially part of the Slytherin house overflow would not find that thought appealing. In fact, a reliance on hard work and justice would repel a student raised to consider family connections of prime importance the issue of the first generation students aside. Given Hufflepuff house no doubt houses both, it is no wonder that Malfoy would rather leave than be sorted there, and I am sure he is far from alone in that thought.
That leaves Ravenclaw. If you cannot be in Noble Slytherin’s house, having a reputation for scholarship and/or intelligence is not a bad consolation prize. Look at the patterns we see in the books. Gryffindors are the good guys, we just ignore the fact that Pettigrew was a Gryffindor. Slytherins are the bad guys, forget the fact that Andromeda Tonks was a Slytherin. What Ravenclaws and Hufflepuffs do we see? Both houses are a fairly mixed bag. We have Hufflepuffs like Susan Bones or Hannah Abbott on one hand and Zacharias Smith on the other. We have Ravenclaws who are members of the DA, and others who steal from Luna.
The only real argument against this is the distribution of first generation students in the various houses. We do not know enough about the students to really have a representative sample. Of those I know, seven are first generation students. Four of those are in Gryffindor, one in Hufflepuff, and two in Ravenclaw. If you look only at Harry’s year, it is two, one and two respectively. Looking at pure-bloods, we have 25, seven in Gryffindor, four in Hufflepuff, four in Ravenclaw, nine in Slytherin, and one we do not know the house of. Again focusing on Harry’s year, that is three, three, three, and nine respectively.
Given our small sample size, I am not willing to accept that these numbers refute my thesis. Despite the prejudices against the first generation witches and wizards, I suspect that all but the most rabid of Slytherin’s followers are willing to use someone. On the surface you might think of Hufflepuffs as being candidates for being used, but I read about the Ravenclaws and I think about stories I have heard about how cutthroat pre-med programs can be, and how students will sabotage each other, or about the quintessential nerds and geeks, so focused on their studies that they do not really perceive the world around them. The first would be nearly a Slytherin, the second would be someone that a Slytherin would easily make use of. He or she would not be to “uppity” as long as you funded their research after all, and could be easily cheated out of any profitable patent-able discoveries…