What is the historical process by which words formerly considered vulgar become simply rude words?
I have noticed a pattern involving vulgarities where the previous generation's evil words become accepted as merely off-color or rude in the following generation. Is this merely each generation's small rebellion against their parents? Does society get bored with certain blacklisted words and move onto different choices?
It seems that some offensive or vulgar words maintain their status far longer than others while some don't last too long. Am I simply suffering from an odd form of selection bias?
Other interesting observations are the choices of insults that particular communities choose to use. Online video gaming has become quite fond of "rape" which is probably a completely inappropriate word to trivialize as meaning pwned. That community seems particularly attracted to violent or overtly offensive terms. Is there a historic precedence for this? Are such communities related to the aforementioned shift in what is considered vulgar?
Solution 1:
You might be looking for the word dysphemism here. See Euphemism & Dysphemism: Language Used As Shield and Weapon by Allan & Burridge.
I have a 20-year-old copy of the book, which I thought was out of print. But I see it's available here.
The authors discuss how certain social classes and segments may use words in a deliberately provocative way, to flout societal norms and demonstrate the countercultural status ("street cred" in current parlance) of the user. If the culture prevails or the wider society finds the words useful, they get adopted, or at least tolerated.
The term jerk-off, for example, was once considered well beyond the pale, but now is a casually derogatory synonym for fool. Similarly, the term motherfucker was once a deadly insult: if you called someone that you could expect to be involved in a fistfight pretty soon thereafter. Nowadays it's not uncommon to hear someone refer to himself as "a bad motherfucker" (cf. Pulp Fiction) and although it's certainly not a word someone would use in polite company, it has been defanged significantly.
And considering your example of the word rape, this has an interesting etymology.
rape ORIGIN late Middle English (originally denoting violent seizure of property, later carrying off a woman by force): from Anglo-Norman French rap (noun), raper (verb), from Latin rapere ‘seize.’ [NOAD]
So you can see that it referred originally to seizure and acquired the sexual connotation later. Now it may be on its way back to meaning aggressive seizure or conquest, though I doubt it will lose the sexual aspect unless a really handy term for that specific meaning variant comes along.
Solution 2:
It's a bit more complicated. Yes, some words get watered down in their vulgarity or strength of stigma, while others increase.
Sometimes a vulgar word gets replaced by a euphemism, but eventually the euphemism gains more and more stigma as to need euphemizing. In AmE, if one needs to ...well... I'll just pick one... urinate, you go to a particular place. The place where you go to do this is nominally the toilet, but at some point in my older relatives' past, they used to call it the commode (which I had only found out recently is nominally a piece of furniture related to the vanity (a metaphorical metonymy on its own)). But nowadays that place is just simply the bathroom, as in "I have to go to the bathroom", which can be literally true since (in US home architecture anyway) almost all rooms with baths in them also have a toilet, but the phrase -means- 'I have to use the toilet'.
(Without checking the OED, I wouldn't be surprised if 'toilet' is the name of some furniture like 'commode' that has become a euphemism for something one urinates into.)
If a word becomes taboo, people still want to refer to the concept, so they come up with another label for it. As the concept itself (whatever word is attached) still remains, the new label might get similar stigmatization and become taboo itself. I'm sure there's a G. B. Shaw quote that's relevant here but I can't remember it or find it.
Other cultural factors come into play. For example, my grandmother used to refer to the descendants of African slaves in the US as 'colored' or 'Negro', both of which sounded slightly shocking, but quaint and old-fashioned at the same time. To us at the time the accepted term was 'black' (there's a whole literature surrounding that word). But now that is not vulgar, just out of fashion, and nowadays the term is African-American.
So some words lose their strength of taboo, others increase and need to be replaced by one with less strength.
As to the particular word mentioned, 'rape', yes, I've heard of similar phenomena of weakening by repetition in that crowd. But fortunately, I really don't think it is translating to the rest of society. Relatedly, the word 'violate' I think used to mean 'rape' but has itself weakened to just mean 'has been transgressed' (argh..I looked things up...rape -used- to mean the weaker thing, simply violent seizing or carrying off, but has come to mean the even more transgressive sexual violation; but that could also be a cultural thing, that it is now considered more of a transgression now than before).
Words and concepts...so confusing.
Solution 3:
I don't think so. Having searched the Oxford English Dictionary and the Cambridge Advanced Learner's Dictionary, I can say that there are no or very less significant English words labelled 'dated vulgar'.
But, the opposite is true for some words. For example, the word negro (once used normally) is now thought as offensive if it is not carefully handled. There are even more words to list, in this case, but I don't think that it'd be fair to speak off the topic.
Solution 4:
Vulgar doesn't in itself imply rudeness. It means the language of the common people, and naturally upper class people would be quite haughty and consider it improper, and to them improper might mean rude, but that's an issue of speaking in the wrong register.
Vulgar words no longer being considered rude would be the result of classism fading out, and much fewer people concerning themselves with register.