But what if they are condemning the whole group?

If and when that happens, deal with it. Saying "all G are" is simply and correctly NOT the same as believing there is not one single G anywhere who isn't. If, when not upset, the person calmly explains the deficiencies of the group, and how it's right that they are persecuted because after all, they are all whatever, then you can react to that then. That is an entirely different conversation. The same as if your friend who said "I"ll kill him!" one day mentions that they have bought a gun or have been interviewing hit men. You'll know when it's different.

@AzorAhai-him- Immediately after an injustice, people will be understandably upset and what they say will not be fair therefore. If that happens, you give them comfort until they feel better - especially if the person was hurt badly. For most people that will a phase. And when they get out of that phase, they will realise that they were unfair. Just letting them cool down will produce a better outcome. If you defend the other group, you can damage your relationship with V badly, even after they cool down.

The problem with that is there are societal double standards when it come to "all G are" phrases. Depending on which group G are, you'll either be defended or vilified, no matter how upset the person is or how genuine their victim status.

the problem with what, @Crazymoomin? Saying "not all G?" - there are lots of problems with it no matter which group G is. It's not useful, helpful, or fair to V to "correct" their hyperbole and defend G, for any G. You are right that saying "some Nazis are kind to their children" is even less helpful.

@KateGregory If I were to say "All women are disgusting" in most situations, even if I'd been abused or harassed in the most horrible way by a women, most people would call me a misogynist pig. If I were to say "All men are disgusting" after experiencing the same thing from a man, then I'd likely be defended by people sympathetic to my circumstances. That's the double standard.

But the question (and my answer) is not about whether V should say "all G are" at all. It's about how someone hearing that should react. And I am not advocating calling V a name or defending V's statement. So your comment seems ... out of place here.

@Kate Gregory My comment is comparing your ideal answer with the reality of how most people react.

ok, so you're saying that most people don't follow my advice, and further that you think many of the responses to "all G are" are bad and unfair. Ok.

@Crazymoomin It seems that I surround myself with too many decent people; in the situation you describe anyone calling V a "misogynist pig" would get an earful (from female family members, and from female colleagues).

This is not what "not all men" refers to. It refers to the idea that any criticism of an "oppressor group", no matter how much of an overgeneralization, must be accepted. The criticism being made in the heat of the moment is not part of the definition. "You're putting the feelings of other G who are not even around to hear this outburst ahead of the hurt person." You're putting an unjustified attack on the feelings of G, that contributes to an environment that encourages more than just hurting feelings, over avoiding a justified hurting of the feelings of the hurt person.

IMHO, "all G are [whatever]" is never okay to say (just like "i'll kill him"), and deserves to be explicitly countered. I find it dangerous to ignore violent speech, regardless who's saying it, or against whom.

you misinterpret it as violent speech. I too oppose casual racism and sexism, as well as hidden variants that talk of "culture fit" -- but when someone is upset and hurt, insisting that every utterance is something they literally mean and need to be corrected about is wrong, and not a way to be a friend nor to stick up for disadvantaged groups. If every time someone said "I'll kill him" you interrupted with an anti-murder speech, you would not in fact reduce the incidence of violence in the world, but you would irritate many people who were looking for support and help.

Eric+Duminil: Context. If you refuse to consider context, and if you insist on having a rigid and flexible mind, you are bound to cause damage.

"if and when it happens, deal with it" Putting aside the completely unsupported 'act as if they don't mean what they say', how would you even do that? Do you just side with them completely in the moment and bring up their incidental G-ism out of the blue later?

in the moment when they are upset, @StopBeingEvil, yes, you focus on their upset, what support they need to move forward, and so on. Later, in a different context, when they say similar words but you now understand due to context that they mean something different, you react to that meaning. So if later they say "we really should get all the G out of this company" you are free to object to that. But I don't share your confidence that everyone who says anti-G things in the heat of reacting to bad behaviour by X will later go on to say anti-G things calmly and coolly and to be anti-G.

Doesn't letting anti-G remarks go by without comment send a message to everyone, including other participants in the conversation, that it's acceptable to make such comments? To some extent, I do feel it matters what G is, since there's a difference between someone hyperbolically saying "all men are [nasty adjectives]" in the midst of a bad break-up, and, say, proclaiming that everyone from a particular country or religion are evil in the wake of a terrorist attack or geopolitical events. Ignoring the latter because the speaker is upset could be interpreted to mean you're ok with intolerance.

you just demonstrated my point. Context matters. Assuming a person literally means everything they say, and that it's your role to correct them if they say something that isn't completely true, is not supportive and helpful.

Zach Lipton, so I know this young mixed-race man who I know has been harassed by the same police officer multiple times. 50 people getting off a train and this piece of ____ picks him out of these people and demands to see his Id. On multiple occasions. So he knows who he is, he’s just harassing this young man because he can. So if I mentioned that and find it upsetting and I said it happens because all police officers are racists, what would you feel bad about? This young man being harassed, or me making some comment about police officers that none of them will ever hear?

@gnasher729 As the accepted answer says, what's wrong with both?

what is wrong with both is that it holds space for the possibly hurt feelings of the offender X, or those like X in G, instead of focusing on your friend V who is having a bad time. It says "what's important here is that I correct you, because I am in charge of such things" and "I can't let anything inaccurate go by, I am the arbiter of whether this is hyperbole or whatever." I would not feel supported by a person doing that.

I believe, you should differentiate between situations where the group is structurally privileged (all men, all cis people, all millionaires) and situations where the group is marginalized (all women, all trans people, all poor people). To my understanding this "not all men" phenomenon is typically discussed in the context of privileged groups.