There is considerable disagreement over which things are roughly good or bad for the world. Encouraging same-sex marriage, speeding the cogs of ‘progress’, compelling would-be immigrants to live in third world shanty towns, and building self-replicating nanobots are considered by different parties to be either substantially positive or substantially negative. Such questions are sometimes loudly and fiercely debated.
There also seems to be much disagreement over how good different good interventions are. Is promoting sustainable agriculture a crucial last-ditch countermeasure in the face of impending societal destruction, or harmless feel-goodery? This type of disagreement seems very widespread, given the huge variety of endeavors people support with their money and time. However such disagreements are much quieter; for the most part people politely get on with their own causes. You are much more likely to be handed a brochure explaining the virtues of buying beads from women in the developing world than one earnestly arguing that this isn’t particularly valuable.
This seems like some evidence of a tragedy of the commons that one might expect prima facie. Even if you can hand out don’t-expend-effort-on-veganism brochures more cost-effectively than the vegans can hand out theirs, you can’t capture the efforts of the would-be vegans for your own preferred cause. The efforts you divert will probably be spread across many other causes.
Ultimately then, the public discussion of causes should become full of hooks to harvest goodwill and efforts, with few working to rescue people from bad causes and replenish the stock. The main demand for counterarguments should come from the people who wish to avoid joining causes themselves. But they don’t need strong cases, just some excuse to say as they decline to join. And indeed, the retorts used for such purposes seem rarely strong enough to change a person’s mind.
One big exception to this tragedy of the commons situation would be causes where people are quite divided – where leaving the pro-X side means joining the anti-X side, and where the anti-X supporters would be happy enough to diminish the X side anyway. These causes tend to be of the first sort I mentioned: where the disagreement is over whether X is excellent or hellish, rather than good or better. For these issues there are no tragedies of the commons, and we should expect to see elaborate cases made for both sides. As of course we do.
Another situation where you wouldn’t see this behavior much is one where most of the causes are considered similarly good by most people, but there are still a few much worse ones. Then a person who understands this state of affairs can redirect most of the efforts they divert from the bad causes toward causes that seem best to them. So if the tragedy of the commons account is right, it seems we are not in that situation. People either think a relatively narrow range of causes are quite good, or that so many causes are quite good there aren’t bad ones around to divert people from.
I don’t know that this is most of the explanation, though it seems it must happen to some degree. People may also prefer not to speak against anything that seems ‘good’ – and measure good against some consistent zero point, not against the opportunity cost. It could also be that the easiest way to compare things is for different parties to make a pro- case for each, then to compare those. Though it seems in practice that would leave out many negative details about each cause. Any other theories? Any reasons to believe or disbelieve this one? Note that the heroes of this story would include the selfless people who go out on the internet night after night, with little to gain by it, tirelessly assaulting any position that shows weakness.