I suspect a part of the appeal of this saying comes from a mental unease with conflicting evidence.
I am quite sure you’re onto something here. A similar effect occurs when people try to argue that a given intervention has no downsides at all; none at all? Really? It will be absolutely free and have beneficial effects on everyone in the world? Why aren’t we doing it already then?
People aren’t used to thinking in terms of cost-benefit analysis, where you say “Yes, it has downsides A, B, C; but it also has upsides W, X, Y, Z, and on balance it’s a good idea.” They think that merely by admitting that the downsides exist you have given up the game. (Politics is the mind-killer?)
We aren’t doing it already because the Bad People have power and if we did it, it would frustrate their Evil (or at least Morally Suspect) Purposes. Frustrating such purposes doesn’t count as a downside. Depending on who you are talking to, taking money from rich people, allowing people who make stupid choices to die, or preventing foreigners who want to from entering your country isn’t just a bad thing that’s outweighed by its good consequences; it simply doesn’t warrant an entry in the “costs” column at all.
I am quite sure you’re onto something here. A similar effect occurs when people try to argue that a given intervention has no downsides at all; none at all? Really? It will be absolutely free and have beneficial effects on everyone in the world? Why aren’t we doing it already then?
People aren’t used to thinking in terms of cost-benefit analysis, where you say “Yes, it has downsides A, B, C; but it also has upsides W, X, Y, Z, and on balance it’s a good idea.” They think that merely by admitting that the downsides exist you have given up the game. (Politics is the mind-killer?)
We aren’t doing it already because the Bad People have power and if we did it, it would frustrate their Evil (or at least Morally Suspect) Purposes. Frustrating such purposes doesn’t count as a downside. Depending on who you are talking to, taking money from rich people, allowing people who make stupid choices to die, or preventing foreigners who want to from entering your country isn’t just a bad thing that’s outweighed by its good consequences; it simply doesn’t warrant an entry in the “costs” column at all.
An aside, but I always hated this argument. It proves way too much. (Cryonics, for example.)