Pigment (or really anything that absorbs/blocks light) is subtractive color. CMY(K) is commonly used in printing, but you could just as easily use RGB pigments instead.

There’s a reason CMYK is used for printing. How are you going to mix RGB pigments to get yellow? R+G won’t work. That’s because red ink filters out green and blue light, and green ink filters out red and blue light. So mixing the two you get something that filters out a bit of everything but especially blue, ie. brown. CMY are used for subtractive color mixing because each one filters out just one of the colors we see (C filters out R, M filters out G, Y filters out B) so you can mix them to get most of the gamut you need.

Your choir has a good reason to be men only, since that creates a certain sound.

That’s true. Which is why I pointed out that my reasons for joining the choir are not just about the sound. I want a male space, and I don’t think I’m wrong to want that.

I don’t think an all-female board game club that is open to the public but only lets women join would be OK.

Personally I don’t see what’s wrong with an all female board game club, especially if it’s the kind of board games that tend to mostly attract male players. It may encourage female participation where they would otherwise feel uncomfortable, and male players would probably have their own club anyway in that case. But then in the absence of a thriving all female club, an all male board game club would be a problematic thing, since it would specifically exclude a female minority. Context matters and it’s important to be inclusive, but inclusivity doesn’t always mean putting everyone in a single group.

But as soon as you do something publicly, you don’t get to say “everybody can come except group X” without a good reason.

OK, but what’s a good reason? We often have groups for limited age ranges, for usually good reasons. You’ve mentioned some good reasons why men should be excluded from some women’s groups. So it’s not like nobody ever gets excluded from anything. And while men may have less compelling reasons to exclude women, in general single sex groups are a valuable social thing for both men and women. One of the reasons you don’t see many strictly single gender clubs is because there are de facto single gender clubs which don’t need to apply a rule. People socialize in a single gender category without having to formally exclude anyone. Which is fine, and avoids unnecessary polemics.

I’m just saying that we should recognize the value in this. It’s a shame that male only spaces tend to be associated with patriarchy or toxic masculinity, when they also fulfill a real social need.

Gender exclusive groups are OK when there is a legitimate reason.

What is a legitimate reason though? Consider…

1. men do not face the problem of being put in uncomfortable situations by women almost anywhere they go, so they have less topics or activities where they feel like they need a men’s only group. For most topics/activities men can go to a mixed-gender group and have the same experience as they would in a male-only group. Women can’t.

You seem to be saying that a legitimate reason would be a need to escape from people hitting on you or the equivalent. How about if you just want to hang out with people of your own gender? Is that not OK? Men do not have the “same experience” in mixed gender groups. Socializing in a single gender group is different from in a mixed gender group and both are important. You are dismissing the need for men to socialize among themselves on the basis that they might make an important decision that should have included people outside that group. Now I understand that this has historically been (and in some cases continues to be) an issue with work-based men’s-only clubs/outings etc, and it should be addressed in that context. But it’s not a valid reason to reject the existence of male only groups or spaces in their entirety, is it?

Case in point: I sing in a male voice choir. I enjoy it not just on a musical level, but also for the fact that it is a male space. It’s not about hating women, or having prejudices about women. It’s not actually about women at all, which is kind of my point. I have enough women in my life, what I need is to be around men sometimes. Nor is it about “we want to address a typical male problem” either, unless you consider difficulty with socializing to be a typical male problem, which, yeah, arguably it is in some cases. But guys just like doing things with guys sometimes. It’s a different dynamic and it’s good for us.

You let them leave the house and meet up with friends, next thing you know they are riding around on bikes! Where will it end?