We like to believe that when it comes to the great global issues of our time—climate change, pollution, poverty, mass extinction—that we each can make a difference. A small one maybe, but a real and significant difference, nonetheless. [...] That’s a mistake. It not only makes us guilt-ridden and worse off psychologically, but even more harmfully it also provides only the illusion of effective action, thereby allowing global problems to fester without a proper solution. [... W]hen it comes to global-scale issues, what individuals do is somewhere between 100 percent pointless and 99.9999999 percent pointless.
There's something right about this, but the central claim is crucially wrong. After all, if you're able to alleviate just 0.0000001% of global harms, that's actually quite a lot of good you've done! You may have saved someone's life, or slightly increased the chance of humanity's continued survival, or slightly increased the average quality of life for future generations (and either of the latter two may in fact involve astronomical amounts of good). Once we grasp the magnitudes involved, it becomes clear that having a proportionate impact is far from pointless.
Hales argues that individual contributions are necessarily wasted "when (1) we solve climate change and your sacrifice wasn’t needed after all, or (2) we fail to solve it and your sacrifice was squandered." There are two major problems with this reasoning. First, it neglects the fact that climate change (like most of the "great global issues of our time") is a graded rather than all-or-nothing phenomenon to be "solved". There is not one thing, climate change, that either happens or not, but rather a spectrum of related phenomena that may become more or less serious depending on how effectively we're able to address the underlying problems.
Secondly, Hales completely neglects the crucial possibility that we end up right at the margin of a major triggering point, such that a major harm is avoided only because of all the individual sacrifices that were made (analogous to an election won by a single vote). This possibility may be extremely unlikely, but so long as the potential impact is proportionately great, the expected value balances out. To ignore tiny chances of momentous events would be a grave moral mistake, as we ordinarily recognize when thinking about investments in nuclear safety, for example.
But there's one thing Hales might be right about, namely, that much moral focus on these (esp. environmental) issues is misplaced. Boycotting plastic straws, for example, is plausibly not worth the bother. But the reason for this is not that individual action is essentially inefficacious in the face of global problems. Rather, it's that the specific action chosen -- avoiding personal consumption of a negligible component of the overall problem -- is of negligible significance.
It's plausibly true in general that our individual consumption habits are not the most high-impact levers we have for changing the world. We can achieve far more through donating to effective charities, voting in high-impact elections, and other outwardly-oriented (philanthropic or political) actions. But these are, of course, still individual actions that we can perform, and it is -- crucially -- up to us to decide to do them. "Collective action" can only be brought about by means of individual actions, after all!
In ignoring these possibilities, and pretending that the only actions available to us as individuals involve trivial decisions about our personal consumption habits, Hales misleads his readers about their potential for improving the world. "Individualistic" philosophical ethics serves us well, I think, in correcting such misplaced fatalism.
[See also: my paper in progress, 'There is No Problem of Collective Harm'.]