How old is the effective altruism movement? It depends when you count from, and it's hard to pick any specific day or event because it coalesced out of a lot of different strands. Plus, since this is a movement and not just an idea, it matters when it started gathering people which is naturally very fuzzy. Roughly, I'd describe the progression as something like:
At the beginning of 2008 there wasn't an EA movement yet, while by 2012 there was one. There wasn't an instantaneous change.
Why this particular curve? Here are some historical points that anchor it to events:
In March 2012, I wrote "there's a young movement that combines the idea of a duty to help others with the idea that you should maximize the impact of your actions," as part of trying to figure out what we should call EA. I'd say it 100% existed by this point, and I wasn't "calling it"—it existed before here.
In November 2011, 80,000 Hours launched. It was mostly a way of spreading ideas that were already popular in the Oxford community and online, so I'd also say the EA movement existed before this. It's a bit less clear than when you have people literally calling it a movement, though.
In December 2010, Roko Mijic ran a contest on LessWrong for the best explanation of EA, which Scott Alexander won with his essay, Efficient Charity: Do Unto Others.... Jonah Sinick also wrote a detailed entry, and Mass_Driver contributed one as well. This feels very movementy to me: a bunch of people working together to put some shared ideas into a form where they'll be able to spread better.
In November 2009, the first 30 people joined Giving What We Can. A group of people pledging to do something seems like part of a movement. At the time GWWC was specific to global poverty, however, so I wouldn't fully count this.
Over the course of 2009, discussion on the Felicifia forum (archive) started to feel like an early EA community. For example, see thread on charity choice and the applied ethics and philanthropy boards.
In December 2006, the first GiveWell blog post comes out. Looking back at it, and their other early posts, you can tell that Holden and Elie had a lot of what has since become EA in mind. This also goes for a lot of other early writing like Nick Bostrom's 2003 post on astronomical waste, Anand's 2003 SL4 "EffectiveAltruism" wiki entry, Brian Tomasik's 2006 post on earning to give, and Eliezer Yudkowsky's 2007 post on scope insensitivity (that coincidentally used the term "effective altruist" years before it was settled on). These are helpful for dating the ideas, but I'm looking for when the ideas started gathering people and they seem to predate most of that.
One thing I'm not putting much weight on here is the founding dates of organizations. While many EA orgs have played a large role in the EA movement, the oldest became EA over time instead of starting out that way. For example, MIRI was founded in ~2000 as SIAI, but was initially wasn't something you'd recognize as EA and didn't have an associated community. It did grow in both of these directions over time, but to the extent that this helps us figure out the timeline of the movement we need to look at those later developments. Similarly, ACE could (but doesn't!) claim to have been founded in 2010 as JFA, but before merging with 80k's EAA it had a pretty different focus.
Another historical point I'd like to make is that the common narrative about EA's recent "pivot to longtermism" seems mostly wrong to me, or at least more partial and gradual than it's often presented to be, because all four leading strands of EA — (1) neartermist human-focused stuff, mostly in the developing world, (2) animal welfare, (3) long-term future, and (4) meta — were all major themes in the movement since its relatively early days, including at the very first "EA Summit" in 2013 (see here), and IIRC for at least a few years before then.
MacAskill was definitely a longtermist in 2012. But I don't think he mentioned it in Doing Good Better, or any of the more public/introductory narrative around EA.
I think the "pivot to longermism" narrative is a reaction to a change in communication strategy (80000 hours becoming explicitly longtermist, EA intro materials becoming mostly longtermist). I think critics see it as a "sharp left turn" in the AI Alignment sense, where the longtermist values were there all along but were much more dormant while EA was less powerful.
There's a previous discussion here
Not necessarily a deliberate strategy though -- my model is that EA started out fairly cause-neutral, people had lots of discussions about the best causes, and longtermist causes gradually emerged as the best.
E.g. in 2012 Holden Karnofsky wrote:
I think a lot of people moved from "I agree others matter regardless of where, or when, they are but figuring out how to help people in the future isn't very tractable" to "ok, now I see some ways to do this, and it's important enough that we really need to try".
Or maybe this was just my trajectory (2011, 2018, 2022) and I'm projecting a bit...
I don't think anyone is denying that longtermist and existential risk concerns were part of the movement from the beginning. Or think that longtermist concerns don't belong in a movement about doing the most good. I think the concern is around the shift from longtermist concerns existing relatively equally with other cause areas to becoming much more dominant. Longtermism is much more prominent both in terms of funding and attention given to longtermism in community growth and introductory materials.
It's really interesting to see, in the thread on charity choice, EmbraceUnity describing their "Utility, Attainability, and Obscurity" framework (see also this blog post from 2008) four years before Holden Karnofsky wrote about the Importance, Tractability and Neglectedness framework. I guess this is a sign that, for some reason, many of the key pieces of EA just fell into place in different locations at around the same time.
Great finding—I was an avid reader of Felicifia but do not recall stumbling upon that particular comment or the associated post. (EmbraceUnity was Edward Miller's Felicifia username, as can be seen by consulting the archived version of Miller's website.)
On the ITN framework, it's also unclear to me whether the version developed by Owen Cotton-Barratt a year or so after Holden's was influenced by those early GiveWell posts. My tentative speculation (~80%) is that Owen was at least aware of Holden's writings, but it's also conceivable that it was an independent discovery. It also seems unlikely to me (90%) that either Owen or Holden had encountered the Felicifia discussion. On the other hand, it's possible (15%?) that Edward Miller's framework reached Owen or Holden in some form via informal channels. For example, Toby Ord, who read Felicifia, may have discussed the idea with Owen.
The "effective altruism" tag on LessWrong has lots of early EA discussion. E.g. here is a comment from Anna Salamon explaining Givewell to Eliezer Yudkowsky in early 2009.
My sense is that early EA summits were pretty important -- here are videos from the first EA Summit in 2013.
The first EA summit was the one you linked in summer 2013, so it just wasn't early enough.
(You could argue that it was important for the movement's growth)
You said you were looking for "when the ideas started gathering people". I do suspect there's an interesting counterfactual where in-person gathering wasn't a major part of the EA movement. I can think of some other movements where in-person gathering is not focal. In any case, I'm not hung up on the distinction, it just seemed worth mentioning.
This is cool! I came across EA in early 2015, and I've sometimes been curious about what happened in the years before then. Books like The Most Good You Can Do sometimes incidentally give anecdotes, but I haven't seen a complete picture in one public place. Not to toot our own horn too much, but I wonder if there will one day be a documentary about the movement itself.
If you think that EA is (a) a community committed to the two ideas of (b) us needing to do far more to help others even at great cost, and (c) doing this as effectively as possible, then we would date EA to 2009 with both the first GWWC pledgers as well as the less organized stuff on Felicifia, since this qualifies on all three counts of (a), (b), and (c). The 2006 and before stuff aren't organized enough to really be considered a community i.e. disqualified on criterion (a) but that's subjective.
Also, I miss the days of Common Sense Atheism! Always interesting to see the proportion of people transitioning from the rationalist anti-theist movement to EA (especially longtermism, but you can definitely see the intellectual overlap)