I'm not in a position to evaluate the strength of the argument of the paper you make versus any other scholarly work on the topic, but there is a book out there that makes the case that moral arguments have played a role in slavery abolition, though perhaps more so in other countries.
See 'Argument and Change in World Politics: Ethics, Decolonization, and Humanitarian Intervention' by Neta Crawford.
(The full article is at the link if you scroll down a bit.)
EAs have worried about "the possibility of an ongoing moral catastrophe" in talks like Moral Progress and Cause X.
One approach to this problem is to look to history (where instances of genuine moral progress are clearer) and see what methods of moral reasoning were used and to what effect. If we find methods that were reliably correlated with moral progress in that past, that may offer hope for the future.
Moral Bias and Corrective Practices: A Pragmatist Perspective looks at moral reasoning and its effects in the case of American slavery. It argues that "the moral biases of slavery advocates proved largely immune to correction by the dominant methods of moral philosophy, which were deployed by white abolitionists. Ascent to the a priori led to abstract moral principles—the Golden Rule, the equality of humans before God—that settled nothing because their application to this world was contested. Table-turning exercises were ineffective for similar reasons. Reflective equilibrium did not clearly favor the abolitionists, given authoritarian, Biblical, and racist premises shared by white abolitionists and slavery advocates."
Thanks very much for sharing this. I actually expected to like it a lot - it's an issue I think about a lot - but ended up being quite unsatisfied.
Historians are often criticised for drawing quite general conclusions from relatively sparse data. For example, I recall reading Seeing Like a State and being concerned that he was drawing conclusions from what seemed like a mere handful of data points, even if new and interesting ones. Or recently I read the recent BIS report on the impact of bank capital requirements on financial crises and growth, and was concerned about the relatively small sample set these conclusions were being based on - even though this data spanned many countries and over a hundred years.
But in this case, Anderson is drawing ridiculously strong conclusions from one single data point - a somewhat biased account of the end of slavery in a single country. There is no recognition that other issues in other geographies and other points in time played out rather differently - even examples as proximate as the history of slavery in England and the Empire. Despite this, she presents her conclusions as being a necessary law of history:
It's also the case that, if her views are true, this is very bad news. A key part of EA is promoting the welfare of groups with no voice, like animals or the as-yet-unborn. Groups that we have concluded deserve consideration, not because of activism by these groups, but by considering our moral intuitions. If the only way of improving the treatment of a group is for that group to practice 'mass resistance' then it is literally impossible for animal rights to ever improve, or the rights of children, or future generations. Fortunately, the fact that we do have animal welfare laws, and child welfare laws, and environmental laws, and so on, suggests that she is indeed wrong.
She seems to miss that moral deliberation and reflective equilibrium have a vital advantage: they are asymmetric weapons, that cut more readily against falsehood, while tending to give succor to the truth. Indeed, they are at the core of the EA project.
In contrast, she presents a very dystopian world, where there is little true moral debate - or if there is, it is of little consequence. All there seems to be is a struggle between powerful groups and almost-as-powerful groups. There is no great tendency here for the arc of history to bend towards justice - just leaders telling the masses that they have been oppressed by a cruel minority and need to rise, which history has shown to be a harbinger of tyranny at least as often as of liberation.
Yup, I agree that she draws strong conclusions from weak evidence. I wish it were more careful, but I posted it anyway since this is really the only analysis I have seen along these lines.