I’m not sure I buy that this is completely about scope insensitivity rather than marginal utility and people thinking in terms of their fair share of a kantian solution. Or put differently, I think the scope insensitivity is partly inherent in the question, rather than a bias of the people answering.
Let’s say I’d be willing to spend $100 to save 10 swans from gruesome deaths. How much should I, personally, be willing to spend to save 100 swans from the same fate? $1000? $10,000 for 1,000 swans? What about 100,000 swans -- $1,000,000?
But I don’t have $1,000,000, so I can’t agree to spend that much, even if I believe that it is somehow intrinsically worth that much. When I’m looking at what I personally spend, I’m comparing my ideas about the value of saving swans to the personal utility I give up by spending that money. $100 is a night out. $1000 is a piece of furniture or a small vacation. $10,000 is a car or a year’s rent. $100,000 is a big chunk of my net worth and a sizable percentage of what I consider FU money. As I go up the scale my pain increases non-linearly, and my personal pain is what I’m measuring here.
So considering a massive problem like saving 2 million swans, I might take the Kantian approach. If say, 10% of people were willing to put $50 toward it, that seems like it would be enough money, so I’ll put $50 toward it figuring that I’d rather live in a world where people are willing to do that than not.
Like many interpretations of studies like this, I think you’re pulling to trigger on an irrationality explanation too fast. I believe that what people are thinking here is much more complicated than you’re giving them credit for and with an appropriate model their responses might not appear to be innumerate.
It’s a hard question to ask in a way that scales appropriately, because money only has value based on scarcity, so you can’t say “If you are emperor of a region with unlimited money to spend, what it is worth to save N swans?” because the answer is just “as much as it takes”. Money only has value if it is scarce, and what you’re really interested in is “Using 2007 US dollars as units: How much other consumption should be foregone to save N swans?”. But people can only judge that accurately from their own limited perspective where they have only so much consumption capacity to go around.
All textbooks should contain a few deliberately placed errors that students should be capable of detecting. This way if a student is confused he might suspect it is because his textbook is wrong.
Starting that in the current culture would be...interesting, to say the least.
I still recall vividly a day that I found an error in my sixth grade math textbook and pointed it out in class. The teacher, who clearly understood that day’s lesson less well than I did, concocted some kind of just so story to explain the issue which had clear logical inconsistencies, which I also pointed out, along with a plausible just so story of my own of how the error could have happened innocently.
I ended up being mocked by both teacher and students as someone who “thinks he knows everything”. Because of course, we all know that the textbook author not only does know everything, but is incapable of making typographical errors.
Oddly, at the time I was remarking on the error to stand up for a classmate who was expressing confusion. She couldn’t understand why her (correct) answer to a question was wrong.