What we think of as social justice advocacy today is a conglomeration of many groups and causes. The core groups are women, ethnic minorities, queer people, and people with disabilities. But there are also other groups that we don’t immediately think about, like polyamory or fat activism.

So, what’s the best way to think of the social justice movement? Is it a single movement with many facets, or is it an umbrella term for many distinct movements?

Here’s one way to think about it (not necessarily the only way or the best way). Social justice is a meta-movement, which seeks to change how social movements and communities work. According to common social justice standards, a feminist movement should pay attention to race. An anti-racist movement should pay attention to queer people. A queer movement should pay attention to disabilities, and so on.

There are a number of justifications for this, which I attempt to list:

1. Similarity of issues – For example, sexism and racism superficially share many characteristics. If you know how to fight one you might also learn to be good at fighting the other. And learning about both can give you a broader perspective.
2. Intersectionality – Queer people of color have their own unique issues which can’t really be addressed unless you pay attention to both queer and POC issues simultaneously. So the only way for a queer group to address the issues of all queer people is to also address issues of race.
3. Pragmatic necessity – Queer organizations can’t address all queer issues within disabilities groups by being on the outside looking in. The only way to meaningfully address queer issues is by having insiders actively addressing them.
4. Tit for tat – It intuitively makes sense for activist movements to help each other out so they can all get ahead.
5. Appeal to moral good – Even if advocating for other minority groups doesn’t advance one’s own cause in any way, one should still do it because it’s the right thing to do.
6. Logical implication – It is commonly argued that cause A is logically implied by cause B. For example, you could argue that anti-queer prejudice is really a form of ableism, therefore queer advocacy entails disability advocacy. (I’m not a fan of this justification, as I favor practical arguments over theoretical ones.)

These are arguments as to why different movements under the social justice umbrella should advocate for each other. But some of the arguments also apply to communities which are not under the social justice umbrella.

For example, it is not only anti-racist groups who should pay attention to gender, physicists should pay attention to gender too. It doesn’t matter that feminism isn’t logically implied by physics, or that physics isn’t “about” feminism. None of that will make up for gender imbalances; none of it will protect physicists from sexual harassment. Physicists can’t simply rely on external feminist activists, who generally won’t pay attention to physicists unless some scandal blows up. Instead, they must have their own internal activism to cultivate a healthy and diverse community. (Indeed, this is a thing that professional physics organizations take seriously.)

Likewise, we have the same expectations of video gamers. Video gamers must pay attention to gender, to race, to sexuality, and to disabilities. Many video game communities are not very good about this (understatement). That is highly regrettable.

So on and so forth.  Apply to any community