I run the social media pages for Effective Altruism Medicine so have had to grapple with the challenging task of explaining EA within a very small number of characters! 

I've been iterating, but currently I'm on:

"A community of healthcare workers aiming to use evidence and careful reasoning to make career decisions that maximise our social impact".

I think for the reasons you touched on, I prefer 'social impact' to 'helping others' and 'doing good'.

For the purposes of our group and for a social media bio, I think focusing on careers rather than volunteering, because as lukasberglund has said in his comment, EA has more developed advice on careers than volunteering. With effective giving, I think that's more relevant when there's more words available to describe the movement, since I think fewer people are already interested in donations, but more people are already interested in impactful careers.

I've also gone for 'career decisions' rather than 'career' to convey that you can improve your impact without switching career paths entirely, but I think this consideration is more specific for our group since we're catering to a profession.

With point 4, I  prefer the framing of "social movement and research field" because I think it's more accurate than just "social movement", and I think the benefits of accuracy here outweigh the costs of having a slightly weaker call to action.

I strongly agree with your points 5 and 6.

I think I consider "evidence and reason" as very central to EA, since I think they're important in setting the community apart from others, and convey how we're prioritising between causes.

Thank you! We most recently had an event with speakers generally discussing high-impact paths related to medicine. We've recently recruited event planners so we haven't started planning new events yet, but we're open to suggestions! We're also hoping to have an in-person meetup around July 2022.

Completely agree with your first 2 points!

With the 3rd, I feel that the incentive to do things that are less effective in absolute terms but more appealing to non-EA funders already exists, and that whether someone should act upon this incentive depends on how much effectiveness they would have to sacrifice, and how their project compares to other potential uses of the EA funding. 

That being said, I'm of the (completely subjective) opinion that there are probably lots of cases where a 'pull non-EA funding towards a relatively more EA project' approach will have a greater counterfactual impact than 'create a very EA project and get EA funding for it' approach. But as Owen said below, it's definitely a case-by-case kind of thing.

As far as I'm aware the main EA electoral reform org (electionscience.org) advocates for approval voting rather than PR, so I think a successful criticism of electoral reform as a cause area would require comparing approval voting and other voting system ideas to both PR and FPTP.

I was thinking about this earlier, it feels like the negative counterfactual impact of starting new charities would be very valuable for someone to investigate.

Also, I agree that "Where is the funding coming from?" is a super important question when assessing replaceability / the counterfactual, and I think a norm of seeking non-EA funding first for EA projects would be a good thing (but it might already be a thing, I'm not sure).

Related to this, a reasonable question I can see progressives asking is "Why do EAs not prioritise anti-racism/ feminism/ LGBT rights?" 

While EAs could argue that drug decriminalisation and criminal justice reform in America are closely related to anti-racism, I think there are some important philosophical questions to answer here related to how EA chooses to define a cause area, and why we don't seem to think of anti-racism / feminism / LGBT rights  as cause areas. I have no idea what a good answer would look like.

I also don't think that the last discussion on this forum of how we define cause areas made much progress.

I agree but I feel that in practice leftists I come across use the term to mean 'working against the class you grew up in', and exclusively use it for people who grew up poor and working class.