By Common Consent has some good thoughts on a post titled "White Is Not a Culture" about how it doesn't make a lot of sense to talk about "white culture" because what's usually meant is "European culture," which is actually a beautiful mix of independent cultures. However, I wasn't entirely sold on this paragraph:
This is not an attack on anyone. “black culture” and “brown culture” are not things either. Neither is “periwinkle culture.” Colors, of skin (or of anything else) are not the sorts of things that can have cultures. That’s just not how culture works.I think it's pretty clear that "black culture" is a thing. At least, African-American culture exists, if our never-failing friend wikipedia is to be believed. There's such a thing as African American vernacular English, food that's associated with African-American culture, not to mention music, literature, and shared social values. I don't see why a group of people sharing a particular race can't have a culture if people from a particular geographic area can. And as a great post I read today that I can't find again said: black Americans have had their ancestry largely erased beyond a general "West African" heritage by the slave trade, and so have had to make their own, new culture in a way that white people haven't.  Celebrating this culture is fine, and in fact great!
So then what would be the problem with celebrating "white culture," too? I think it comes down to what race is: a social construct. That's a fancy way of saying that it's a jointly understood but ultimately made-up classification. "White" and "black" (and "asian" and etc etc) did not exist hundreds of years ago; they were invented by Europeans about the same time they started the African slave trade. Before that, skin color was just another thing like eye color--a curiosity, but not meaningful in any real way in society.  This can be seen in, among other things, the way the definition of "white" has changed over time. Polish people, Italians, Jews, and even Mormons (!) haven't always been considered "white." 
"White" people put themselves at the top of the racial hierarchy they invented (surprise, surprise). So by definition, "white" meant "the superior race," while the "black race" was by definition "inferior."  And that, I think, is why it ends up being so problematic to celebrate "white pride": it means that you're celebrating your status in the supposedly superior race.  "Black pride" isn't a problem under this view because it's a form of reclaiming an initially negative trait and taking pride in it. "White culture" is code for "superior culture" in a way that Irish culture or Norwegian culture is not.
So by all means, I'm proud of my Italian, English, Danish, Irish, and Swiss heritage , but I wouldn't say I'm "proud" of my white heritage. "Whiteness" has meant the creation of "lesser" races, a legacy I'm not proud of. I'm not saying that being white is bad or something to feel guilty for, but it's definitely something to be aware of. "White pride" is not OK. It amounts to white supremacy.
 Update as of 8/21/17: Found it!
 In the same way, "straight" wasn't a thing until "homosexual" was invented.
 But see https://www.washingtonpost.com/news/volokh-conspiracy/wp/2017/03/22/sorry-but-the-irish-were-always-white-and-so-were-the-italians-jews-and-so-on/ for a contrary view on this point. I disagree, but I'm no expert, and really this point is more of a tangent for purposes of this post anyway.
 "White" being at the top explains why it's so fragile. (Under the infamous "one-drop rule" in the US, a single black ancestor meant that someone who looked as white as could be was actually considered black.) It was really easy to topple from the lofty peak of whiteness, but very hard to get back up to it once you'd fallen.
 But explains, I think, why "white culture" can be quote unquote "celebrated" by drinking pumpkin spice lattes or visiting sites like https://stuffwhitepeoplelike.com/--it's done semi-tongue in cheek, understanding that it's not in any way claiming that "white" is better than anyone else (and sometimes is even hilariously lame).
 I'm trying to remember all the groups my mom's genetic test came back with . . .