(1) The "Altruism" bit: A commitment to making the world a better place -- including a willingness to expend some non-trivial proportion of one's own resources to this end.
(2) The "Effective" bit: A commitment to using these resources as effectively and efficiently as possible (based on the best available evidence, analysis, etc.).
And I guess there's a further 'movement-building' element that is perhaps common to all movements:
(*) The belief that others should do likewise.
Now, these core commitments seem pretty innocuous to me, so I'm always a bit baffled when I see people objecting to EA as such. (Why would anyone be against making the world a better place?)
Of course, there's plenty of room for internal disagreement about what is actually most effective. EAs vary between whether they prioritize (e.g.) traditional global poverty charities, (farm) animal welfare, meta-charities, global catastrophic risk mitigation, or public policy / lobbying. The former cause area, with its robust supporting evidence, is emphasized in materials directed at popular audiences, for obvious pragmatic reasons (e.g. the prominence of aid skeptics, and the popular tendency to dismiss anything that sounds too "weird"). This has unfortunately led some academic critics to assume that EA is all about short-term thinking, which really couldn't be more wrong.
One of the internet's most, um, rhetorically strenuous critics of Effective Altruism is Brian Leiter, who in his most substantial post on the topic to date writes:
What if instead of picking worthy charities in accordance with Singer’s bourgeois moral philosophy, those with resources committed all of it to supporting radical political and economic reforms in powerful capitalist democracies like the U.S.; perhaps even committing their time and resources to helping other well-intentioned individuals with resources organize themselves collectively to do the same? Is it implausible that if all those in the thrall of Peter Singer gave all their money, and time, and effort, to challenging, through political activism or otherwise, the idea that human well-being should be hostage to acts of charity, then the well-being of human beings would be more likely to be maximized even from a utilitarian point of view? Do Singerites deny that systemic changes to the global capitalist system, including massive forced redistribution of resources from the idle rich to those in need, would not dwarf all the modest improvements in human well-being achieved by the kind of charitable acts Singer’s bourgeois moral philosophy commends? The question is not even seriously considered in the bourgeois moral philosophy of Singer. Although purporting to be concerned with consequences, like most utilitarians they set the evidential bar so high, and the temporal horizon so short, that the actual consequences of particular courses of action, including the valorization of charity over systemic change, are never really considered.
I don't see any objection to the core commitments of EA here, just a dispute about means. Leiter may insist that even if his proposals don't violate the letter of EA, they nonetheless remain contrary to the ethos of the movement, and would (in practice) be dismissed out of hand in a way that reveals the movement's fundamental shortcomings (such as the alleged focus on "modest improvements" over an unjustifiably short time horizon). But I actually think this latter assumption is just false. In particular, Leiter -- like many critics of EA -- seems to have an unduly restrictive conception of "charity" compared to the wide range of EA-supported organizations I listed above. Whatever organizations you think could do the most good with additional funding (and I don't see anyone policing people's sincere and considered judgments here), you should be donating to them.
Now, it's clearly not true that the EA movement is in general opposed to low-probability high-impact bets over long time horizons. After all, a popular point of ridicule is the prominence given to concerns about artificial intelligence and Bostrom-style reasoning about the overwhelming importance of existential risk ("X-risk") reduction. (Srinivasan's critical review, which Leiter praises, is even called "Stop the Robot Apocalypse"!)
So I'm a bit puzzled as to why Leiter and his ilk present themselves as external critics of EA, rather than hopping on board and making internal criticisms / suggestions about how best to achieve our shared goals.
On the substantive merits of his proposals, though, the political radical is here in an awkward position. If one wants a "safe bet" for improving the world, the global poverty or animal welfare wings of EA are clearly the way to go. If one wants the "best bet" in expected value terms, and is willing to make optimistic estimates in the absence of a robust evidence base, the meta and X-risk wings of EA are clearly the way to go. It's difficult to find any principled evaluative standpoint from which radical politics looks distinctively promising. (Personally, I'm inclined towards making the "best bet" in expected value terms with moderately pessimistic priors in the absence of a robust evidence base, which leaves me at least somewhat sympathetic to the whole range of EA focus areas, including policy reform, but rather skeptical of radical politics. Note that I would be much less enthusiastic about global poverty charities were it not for the potential flow-through effects.)
At least, so it seems to me at first glance. But there's room for discussion, and I'm sure that most EAs would welcome a serious discussion about how best to evaluate the various options on offer to us as individuals (which include political actions). Like McMahan, I haven't yet seen any such serious analysis from the philosophical critics of EA. (They generally seem more interested in signalling how very Left they are by complaining about how "bourgeois" or "consumerist" EA seems to them, and how horrified they are that anyone could ever possibly justify working in the financial sector, etc.) But it certainly would be welcome. Critics' denigration of individual philanthropic action per se is, by contrast, just bizarre and unhelpful -- providing cover and solace to the morally complacent.