This is the basic logic behind #notallmen, a hilarious liberal meme that emerged in the wake of whatever era-defining cable news or Twitter controversy that I've evidently already forgotten. Men's Rights Activists and monstrous reactionaries would try to change the subject away from the problems of patriarchy by bringing up exceptions to the critique - typically, instances where "not all men" were to blame. Rather than explaining why that rhetorical maneuver is a problem, everyone just responded with the "not all men" line - a pithy, self-parodying summary of the standard formula.
As a feminist, I love #notallmen - it's a great way of responding to a stupid, dishonest deflection.
But as a student of political rhetoric, it troubles me. Because like all canned responses, #notallmen is what Orwell called the "invasion of one's mind by ready-made phrases". Instead of indicating thoughtful politics, it indicates the replacement of thought with prefabricated slogans.
The proof of this is when you see #notallmen misused. How? Paradigm example:
For one day only #NotAllMen are awful. Donate to @SaveWiyabi & prove you're the exception with a donation http://t.co/qxyvoVTwU4 …Again: #notallmen ridicules disproportionate attention to exceptional claims. It is not a sarcastic way of insisting that those claims are necessarily false. It does not actually propose that #yesliterallyallmen are anything in particular - even awful.
— Shaadi (@tgirlinterruptd) July 31, 2014
Shaadi's tweet does not imply some generalized statement about men or patriarchy, with all of the obvious caveats and qualifications left unspoken (because they're irrelevant). It can only be read as offering a "one day only" exception to what must be sensibly understood as an absolute claim that all men are indeed awful - a claim made not in the service of feminist critique, but in the service of a crass fundraising pitch.
#Notallmen is not a license for liberals to make demonstrably unfair and untrue claims for whatever reason they like.
None of this is to say that #notallmen has sparked some kind of serious or even significant problem of "reverse-sexism," as the reactionaries would probably call it. Sorry MRAs, not even a few semi-erudite liberals and their misunderstanding of an internet meme are enough to turn you into the real victims. There is still that thing where you are men in a world dominated by men, and that kind of privilege doesn't really get offset by the latest mean thing some doofus said on the internet.
What it does say is that liberals aren't necessarily thinking liberally when they invoke liberal memes, even if they happen to be right. Sometimes, in fact, liberal memes can indicate some pretty toxic reactionary ressentiment - as when this person explicitly applauds misandry and tacitly identifies feminism with a hatred of men. #Yesallmen is just particularly useful for demonstrating this sort of problem, because it's relatively easy to demonstrate when the line is being abused by people who don't understand it.