This is a special post for quick takes by Sammy Martin. Only they can create top-level comments. Comments here also appear on the Quick Takes page and All Posts page.
An extremely unscientific and incomplete list of people who fall into the various categories I gave in the previous post:
1. Accept Convergence and Reject Normativity: Eliezer Yudkowsky, Sam Harris (Interpretation 1), Peter Singer in The Expanding Circle, RM Hare and similar philosophers, HJPEV
2. Accept Convergence and Accept Normativity: Derek Parfit, Sam Harris (Interpretation 2), Peter Singer today, the majority of moral philosophers, Dumbledore
3. Reject Convergence and Reject Normativity: Robin Hanson, Richard Ngo (?), Lucas Gloor (?) most Error Theorists, Quirrell
4. Reject Convergence and Accept Normativity: A few moral philosophers, maybe Ayn Rand and objectivists?
The difference in practical, normative terms between 2), 4) and 3) is clear enough - 2 is a moral realist in the classic sense, 4 is a sceptic about morality but agrees that irreducible normativity exists, and 3 is a classic 'antirealist' who sees morality as of a piece with our other wants. What is less clear is the difference between 1) and 3). In my caricature above, I said Quirrell and Harry Potter from HPMOR were non-prescriptive and prescriptive anti-realists, respectively, while Dumbledore is a realist. Here is a dialogue between them that illustrates the difference.
Harry floundered for words and then decided to simply go with the obvious. "First of all, just because I want to hurt someone doesn't mean it's right -"
"What makes something right, if not your wanting it?"
"Ah," Harry said, "preference utilitarianism."
"Pardon me?" said Professor Quirrell.
"It's the ethical theory that the good is what satisfies the preferences of the most people -"
"No," Professor Quirrell said. His fingers rubbed the bridge of his nose. "I don't think that's quite what I was trying to say. Mr. Potter, in the end people all do what they want to do. Sometimes people give names like 'right' to things they want to do, but how could we possibly act on anything but our own desires?"
The relevant issue here is that Harry draws a distinction between moral and non-moral reasons even though he doesn't believe in irreducible normativity. In particular, he's committed to a normative ethical theory, preference utilitarianism, as a fundamental part of how he values things.
Here is another illustration of the difference. Lucas Gloor (3) explains the case for suffering-focussed ethics, based on the claim that our moral intuitions assign diminishing returns to happiness vs suffering.
While there are some people who argue for accepting the repugnant conclusion (Tännsjö, 2004), most people would probably prefer the smaller but happier civilization – at least under some circumstances. One explanation for this preference might lie in intuition one discussed above, “Making people happy rather than making happy people.” However, this is unlikely to be what is going on for everyone who prefers the smaller civilization: If there was a way to double the size of the smaller population while keeping the quality of life perfect, many people would likely consider this option both positive and important. This suggests that some people do care (intrinsically) about adding more lives and/or happiness to the world. But considering that they would not go for the larger civilization in the Repugnant Conclusion thought experiment above, it also seems that they implicitly place diminishing returns on additional happiness, i.e. that the bigger you go, the more making an overall happy population larger is no longer (that) important.
By contrast, people are much less likely to place diminishing returns on reducing suffering – at least17 insofar as the disvalue of extreme suffering, or the suffering in lives that on the whole do not seem worth living, is concerned. Most people would say that no matter the size of a (finite) population of suffering beings, adding more suffering beings would always remain equally bad.
It should be noted that incorporating diminishing returns to things of positive value into a normative theory is difficult to do in ways that do not seem unsatisfyingly arbitrary. However, perhaps the need to fit all one’s moral intuitions into an overarching theory based solely on intuitively appealing axioms simply cannot be fulfilled.
And what are those difficulties mentioned? The most obvious is the absurd conclusion - that scaling up a population can turn it from axiologically good to bad:
Hence, given the reasonable assumption that the negative value of adding extra lives with negative welfare does not decrease relatively to population size, a proportional expansion in the population size can turn a good population into a bad one—a version of the so-called “Absurd Conclusion” (Parfit 1984). A population of one million people enjoying very high positive welfare and one person with negative welfare seems intuitively to be a good population. However, since there is a limit to the positive value of positive welfare but no limit to the negative value of negative welfare, proportional expansions (two million lives with positive welfare and two lives with negative welfare, three million lives with positive welfare and three lives with negative welfare, and so forth) will in the end yield a bad population.
Here, then, is the difference - If you believe, as a matter of fact, that our values cohere and place fundamental importance on coherence, whether because you think that is the way to get at the moral truth (2) or because you judge that human values do cohere to a large degree for whatever other reason and place fundamental value on coherence (1), you will not be satisfied with leaving your moral theory inconsistent. If, on the other hand, you see morality as continuous with your other life plans and goals (3), then there is no pressure to be consistent. So to (3), focussing on suffering-reduction and denying the absurd conclusion is fine, but this would not satisfy (1).
I think that, on closer inspection, (3) is unstable - unless you are Quirrell and explicitly deny any role for ethics in decision-making, we want to make some universal moral claims. The case for suffering-focussed ethics argues that the only coherent way to make sense of many of our moral intuitions is to conclude a fundamental asymmetry between suffering and happiness, but then explicitly throws up a stop sign when we take that argument slightly further - to the absurd conclusion, because 'the need to fit all one’s moral intuitions into an overarching theory based solely on intuitively appealing axioms simply cannot be fulfilled'. Why begin the project in the first place, unless you place strong terminal value on coherence (1)/(2) - in which case you cannot arbitrarily halt it.