> A contemporary one would be cutting down on CO2 emissions. It's everyone's duty to cut back on that
You have just illustrated why the concept of duty has lost a lot of power: it got misused.
I don't agree with you that it is my duty to cut back on CO2 emissions, because I don't agree with the underlying factual belief that leads you to make that claim. Every claim of duty rests on some underlying factual belief like that: but if we're talking about, say, the duty to pick up litter in a public park because it's a shared space, the underlying factual belief--that the public park is a shared space with shared responsibility for maintenance, and that littering decreases the value of that space--is much easier for everyone, or at least a majority, to agree on.
Of course, that still doesn't guarantee that everyone will agree; someone else upthread described kids in a public park telling him to mind his own business when he pointed out that they were littering. They obviously didn't share his factual belief about what kind of shared space the public park was or the impact of littering on it. But it took quite some time for society to reach the point where that concept of duty was no longer felt. And a major reason why that happened was that people with certain policy agendas tried to manipulate other people's sense of duty based on factual beliefs that weren't as widely accepted or easily supported as the belief about public parks and littering.
You have just illustrated why the concept of duty has lost a lot of power: it got misused.
I don't agree with you that it is my duty to cut back on CO2 emissions, because I don't agree with the underlying factual belief that leads you to make that claim. Every claim of duty rests on some underlying factual belief like that: but if we're talking about, say, the duty to pick up litter in a public park because it's a shared space, the underlying factual belief--that the public park is a shared space with shared responsibility for maintenance, and that littering decreases the value of that space--is much easier for everyone, or at least a majority, to agree on.
Of course, that still doesn't guarantee that everyone will agree; someone else upthread described kids in a public park telling him to mind his own business when he pointed out that they were littering. They obviously didn't share his factual belief about what kind of shared space the public park was or the impact of littering on it. But it took quite some time for society to reach the point where that concept of duty was no longer felt. And a major reason why that happened was that people with certain policy agendas tried to manipulate other people's sense of duty based on factual beliefs that weren't as widely accepted or easily supported as the belief about public parks and littering.