I have this conversation way too often:
Someone: Why do we need feminism? If you want to make the world better for everyone, why not just equalism, or everyoneism, or everythingism?
Me: Because horrible things are happening to women. Disproportionate rape and domestic violence and blatantly unfair laws in other counties... I could go on.
Someone: Well that's obvious. But those aren't feminist issues, they're human issues.
So it begs the question, when is something a feminist issue, and why do we need this label? I feel like way too often we want to define "feminist issue" as "something only women care about". And that's why we think we don't need feminism... because I can't think of anything only women care about. If men care about us, they have to care about what we care about, right?
I've said many times that feminism is a discipline within the umbrella of "things that make the world a better place".
We need disciplines because they give us focus.
For example: I'm an engineer by day. An electrical engineer, who makes airplanes. Being an electrical engineer doesn't mean I don't care at all about the load factors on the wings. It just means that we realized we couldn't build an airplane by dumping 100 pounds of sheet metal in a room and telling everyone "go at it". We divided up the tasks into disciplines.
Sometimes the airplane has electrical problems. Electrical problems are also airplane problems. Just like oppressing women can stifle an economy, cutting a wire can keep an engine from cranking up.
Everyone cares about electrical problems.
We call something an "electrical problem" because there's a collection of problems caused by the same things: interference, undervoltage, heat dissipation, signal loss etc. I, the electrical engineer, am used to focusing on those issues. By having this specific background, I'm more likely to recognize and correct electrical issues. I spend more of my time focusing on these problems, so I can compare them to each other and get better at fixing electrical issues.
Can you fix an electrical issue if you've never hooked up a voltmeter? Sure. Could I still recognize & fix a mechanical issue? Sure. But all of us who've built airplanes have decided that "electrical" deserves to be a specific discipline, there's enough stuff in that category that we've got specific questions that are helpful to focus on.
So back to feminism. We'd like to lower domestic violence rates, and improve the lives of survivors. Would it help if we had knowledge of stereotypes, media tropes, cultural acceptance of victim blaming, or unbalanced economic power? Do those things affect only the lives of domestic violence survivors, or are they also a detriment to sexual assault survivors, struggling single mothers, girls who avoid science careers?
None of these are issues that only women care about. But feminists say that they're all related, and there's a specific set of questions we should be asking ourselves about them. That's what a discipline is. It's a lens, taking a special interest in what we're learning together, and admit that these causes benefit from some prior related knowledge.
To be a feminist you don't need a special degree or certificate, you just have to be aware of the issues women face in our world and admit that those issues deserve some focus. You can still address men's issues, save the whales, campaign for fair wages, feed hungry children. You definitely don't have to be a woman. You just have to look up and say, "Hey... we can make the whole world a better place if we ask some questions specifically about women."