An earlier post detailed the recent rise of all sorts of slang words which presume that nobody else is inclined to trust you, so you have to insert these overt declarations that you're not lying to them. Most revealingly, "I'm not gonna lie." It's like everybody thinks that their peers are going to judge them as the boy who cried "wolf."
This preoccupation with establishing your trustworthiness includes a range of other widespread qualifiers. They all have the common theme of speaking as though you were a witness testifying before a skeptical jury. At the outset, you labor to establish your credibility, as though you're an expert or in a special position of knowledge and experience. When you lack convincing expertise yourself, you appeal to someone else's authority. And when all else fails, you phrase bare opinions as matters of fact.
It's tough to investigate how this behavior has changed over long periods of time because the particular phrases that people use for these purposes may differ across time. So I've kept only phrases that are generic, formulaic, and enduring, rather than specific buzz-words that may fluctuate more according to fashion. Even formulas come and go, but on longer time scales. I'll be looking here just at changes within the past couple decades.
Also, everyday speech generally does not get written down, so I'll look at what's stored in the media, and journalistic sources rather than books in general. They tend to have more opinion pieces where the writer is speaking personally, or quotes from people offering their opinion, than books do. The New York Times will serve as a snapshot of the broader society, but I've also consulted the Harvard Crimson to get a closer look at youth culture, which tends to be a greater source of innovation (for better or worse).
Finally, isolated cases do not establish a broad or lasting trend. A trend needs to continue itself. Occasionally I've mentioned where there are isolated cases, to show that the phrase existed before the trend began, but was not a mass phenomenon.
First are prefacing statements of the rough form, "As a ___, I...." The "as a" clause seeks to establish credibility, and the second clause is the opinion, piece of advice, etc. The search engines of the NYT and Crimson won't let me do that, and I'm not going to write a program that does. So I've looked at three examples that fill in the blank, and only where they're used to set up another clause -- the one we might otherwise ignore or dismiss. Not where they're used as descriptions ("he will be remembered as someone who cared deeply for his friends").
As a long time... This is an obvious appeal to greater experience than the average person has. It first appears in the Crimson in 1997. The NYT shows isolated cases in 1987 and '89, but is not part of a trend until 2000.
"As a long-time advocate of pre-registration for classes, at the beginning of each semester I try to rebel against shopping period as much as possible." (Crimson)
"As a long-time student of human development, the whole issue of what makes for a good education..." (NYT)
As a person who... Again, the speaker has special experience or qualifications. The Crimson shows an isolated case in '79 but does not get going until 1993 (further cases show up in 2000, '08, '11, and '11 again). In the NYT, it begins in 1992.
"As a person who had a sister who was a police officer and who was murdered, I would certainly not endorse or condone violence of any kind ..." (Crimson)
"As a person who has lost family members to lung cancer, I'd want to know before donating whether a charity takes tobacco money." (NYT)
As a believer in... This shades into the appeal to authority, namely the soundness and trustworthiness of whatever it is that you're a believer in. The Crimson has an isolated case in '71 but doesn't get going until 1992. For the NYT, it is 1987, the only example from the '80s (and then, the late '80s).
"As a believer in original sin, I figure that goal is never met, but you can move toward it, I suppose..." (Crimson)
"As a believer in the value of advertising, I marvel that such indifference exists in this region." (NYT)
X famously said... Unfortunately I couldn't use phrases like "X himself said..." to study the appeal the authority. People generally don't phrase it so bluntly; they take more time and elaboration when citing authority. Rather, "X himself said..." is used more to make it sound unexpected or contradictory (like "Snooki herself said there's such a thing as too much tanning"). When people want to introduce a belief, opinion, etc., that we're supposed to buy for authority reasons, the most succinct way they phrase it is "X famously said..." It first appears in the Crimson in 1999, and in the NYT in 1995.
'Herbert selects the very topics that demand linguistic self-consciousness, save that topic of genocide and terror which Adorno famously said would make "all lyric after the holocaust...barbaric." ' (Crimson)
"Oscar Wilde famously said that all bad poetry is sincere, and the same could be said of bad painting." (NYT)
It is the case that... Now we get into phrases that just deny that there's anything up for debate. Nobody uses it for factual statements, like "It is the case that the sky is blue on a clear afternoon." This sleight-of-hand shows a preoccupation with your credibility, only deflecting any possible concerns as Objectively False. And it differs from merely stating an opinion without a qualifier, where any non-autistic person can tell it's an opinion, and instead prefacing it with a "this is the Objective Truth" clause. This phrase first appears in the Crimson in 1994, and the NYT in 1998.
"Clearly it is the case that a vital goal of many course[s] is the building of a body of knowledge making analyses possible..." (Crimson)
[Bonus points for throwing in "clearly" and "vital" as well. What a dickless retard.]
' ''It has been the general view -- and I think it is the case -- that Delta has been weak in the marketing area,'' Mr. Mullin acknowledged.' (NYT)
It is clearly... As above. The Crimson has an isolated case in '73, and gets going in either 1991 or '94. In the earlier example, it sounds like the "clearly" belief isn't so much of a subjective judgement -- whether a building is well-crafted is more of an objective thing. He's using that damning by praise to introduce a more subjective assessment -- that the building's context is disregarded. The later example is clear, though. The NYT has too many examples too inspect to see if they are used in the intended way, and chart the change over time.
"It is clearly a very well-crafted building," Eck says, "but the context is almost totally disregarded." (Crimson, 1991)
'When, on their last LP Check Your Head, Mike D raps "I live my life just how I like to," it is clearly more than commonplace rap bravado.' (Crimson, 1994)
It is obviously... It first appears in the Crimson in 1997. As above, the NYT has too many examples to inspect.
"There has been only one African-American general manager in the history of the game [of baseball]. It is obviously not a question of quality since this general manager, Bob Watson, helped build the World Series winners in New York." (Crimson)
I'm sure there are other phrases to look at, but this gives a pretty good view of the pattern. The trend is confined to the past 20 years. It was in some kind of trial-and-error stage in the late '80s / early '90s, and took off after that. How this all relates to broader social trends was already discussed in the post on "trustworthiness" slang.