I think your objection to 3 doesn't work. He's not saying that even if something is not objectively wrong there can't be a reason to do it, he's saying the lack of wrongness itself doesn't provide a reason to do it. Rightness would provide a reason, sure, but that's not the property he's talking about. He's saying "not wrongness" doesn't provide a reason. Like how the fact that it's it not wrong to cross the street doesn't itself provide a reason to cross the street
I wrote a very similar argument a while ago about utilitarianism. Seems like we converged on the same point. But yeah, subjective/objective distinction.
Hmm, but isn't the obligation to not engage in unnecessarily risky behavior an objective one? I'm thinking about someone who, I don't know, likes driving really fast late at night on streets that are usually empty. He's obviously got a subjective moral reason to avoid doing it, because there might be people driving on them every once in a while. But it also seems obvious to me that he has an objective moral reason to heed that subjective moral reason, because we all have an objective moral reason to avoid unnecessary moral risk. If it turns out no one was driving on the road that night, I wouldn't think "Oh thank goodness what he was doing wasn't actually immoral, even though it might have been" in the way your subjective framing suggests - I would think it was still immoral, period, because doing something that poses a serious risk of being immoral is, itself, immoral. So I think the argument still goes through!
I think your objection to 3 doesn't work. He's not saying that even if something is not objectively wrong there can't be a reason to do it, he's saying the lack of wrongness itself doesn't provide a reason to do it. Rightness would provide a reason, sure, but that's not the property he's talking about. He's saying "not wrongness" doesn't provide a reason. Like how the fact that it's it not wrong to cross the street doesn't itself provide a reason to cross the street
I wrote a very similar argument a while ago about utilitarianism. Seems like we converged on the same point. But yeah, subjective/objective distinction.
https://www.parrhesia.co/p/probabilist-reasons-to-reject-utilitarianism
Hmm, but isn't the obligation to not engage in unnecessarily risky behavior an objective one? I'm thinking about someone who, I don't know, likes driving really fast late at night on streets that are usually empty. He's obviously got a subjective moral reason to avoid doing it, because there might be people driving on them every once in a while. But it also seems obvious to me that he has an objective moral reason to heed that subjective moral reason, because we all have an objective moral reason to avoid unnecessary moral risk. If it turns out no one was driving on the road that night, I wouldn't think "Oh thank goodness what he was doing wasn't actually immoral, even though it might have been" in the way your subjective framing suggests - I would think it was still immoral, period, because doing something that poses a serious risk of being immoral is, itself, immoral. So I think the argument still goes through!