Hi Namit!
I pretty much agree, but I’m wondering about a couple of fine points.
I’m not perfectly clear on the distinction among the three, or at least the distinction between pluralism and universalism. Universal general principles of morality or theories of value would have different less-general implications in different places because of different local facts. For example, the point that what counts as an immoral waste of water is different in Mali and in Costa Rica isn’t going to seem like a challenge to a very general universal theory like utilitarianism. Cultures are local facts. So what distinguishes universalism from pluralism?
You seem to say the universalist and pluralist differ in some view about human nature and its relation to morality, but I’m not sure what belief is supposed to mark a universalist. One of these?
1. Humans have human nature in common.
2. There is such a thing as human nature.
3. Morality can be read directly off our common human nature.
4. We have enough of a common human nature that the same rules apply to every human community.
#1 seems to me nearly a tautology. If we didn’t mostly have it in common, it wouldn’t count as human nature. That doesn’t say anything about how flexible are the potentialities that constitute whatever human nature we may have.
One might challenge #2 on the grounds of a religion that says we are not really biological creatures, we are spiritual creatures who have no limits. Or one might challenge it on the grounds that the idea of a biological species is an oversimplification.
I wonder whether someone has to be a universalist to believe #3. One might think there are universal rules that are not readable directly from human nature because they are rooted in only very modest assumptions about human nature in combination with views about other things such as God’s commands, or principles of epistemology (free discussion is a necessary condition for rational knowledge of big things) or prinicples of economics (basic material well-being normally depends on private property) or some combination of the above.
#4 abandons the idea that universalism is distinguished by any view about human nature.

Alas, it doesn’t help!
Let’s say “Wantism” is the view that a legal right to X is justified in a certain community if and only if in that community a desire for X is widespread, strong, and hard to eradicate. That is, the stronger and more ineradicable and common a desire for X is, the more it is true that people should have a right to it (and the weaker, more eradicable, and less common a desire for X is, the less it is true that people should have a right to it).
If Wantism is true, then whether rights are universal depends on the factual question whether there are strong natural universal desires whose objects are concrete enough to be described and protected by public rules. Wantists who have different views on that factual question will differ over universalism v. pluralism about rights, yes? If a certain Wantist thinks that all our strong wants are natural to our species, then she’ll be a universalist about rights, because of her view of human nature and because she’s a Wantist. She’ll think rights can be read fairly directly off human nature, given Wantism.
But maybe there has never been a Wantist. Let’s make up another character – “Millton Freeman” – who thinks that the reasons why rights are important have to do with features of epistemology and economics that are to a very large degree independent of which things people want (for example, whether people naturally want to ramble or to settle down with kids). The economic and epistemological arguments are independent of whether people naturally want to be free to speak or to own property. Millton might think the main list of rights that should be protected is universal while having no view about human nature beyond points that are obviously universal such as the capacity for language, hunger and thirst, some capacity for greed and corruption, etc. Millton might or might not think history is going his way.
Millton Freeman doesn’t seem to have a place in your list of possibilities. He’s not a pluralist because he believes the same main rights are best for everyone, at least after a period of adjustment; but he’s not a universalist because he doesn’t have the associated views about human nature (or about history).
Someone’s theory of rights might be grounded in a very specific view of universal human nature even if (like Kant) she is sure it isn’t – for example if (like Kant) she has never gone far from Königsberg, so she does not notice her assumptions about human nature. But that doesn’t mean there aren’t respectable arguments for (at least some) universal rights that don’t depend on any fine points about human nature.
(You write: “Utilitarianism says that everyone in Mali with a utilitarian approach should, in theory, reach the same conclusions”. Utiltitarianism would strike the phrase ‘with a utilitarian approach’. That’s why utilitarianism isn’t a form of relativism.)
Your opening paragraph seems to want to distinguish between facts of “context” and facts of culture or some other kind of local fact. Are you saying that universalism says morality is responsive to the former and not at all to the latter? Utilitarianism would seem in principle responsive to every kind of fact.

Namit, your Darjeeling photographs look like paintings by Roerich.
I think a universalist view can be
(N) dependent mainly on a view of human nature,
(NO) dependent on a view of human nature and on other things,
(O) dependent only on other things.
In case (NO), there might be only a small dependence on weak or uncontroversial views about human nature.
In your Ah-ha! paragraph you seem to say:
“Bill, you say (NO) is possible. I disagree. Can Millton be an example of (O)? No! Millton has to be relying at least in part on a view of human nature; that is to say, he must be either (NO) or (N).”
In the comment you were answering, I said that Millton is an example of (NO), but that he doesn’t rely on the idea that human nature is uniform on fine points.
In the second chapter of On Liberty, Mill argued that freedom of expression is essential because we’ll will make bigger mistakes on big questions if our views aren’t open to challenge. It’s a pretty good argument, and it would seem to have application not only to humans but also to many other sorts of intelligent species we may expect to find on other planets. The argument doesn’t depend on the fine points of the species.
I haven’t read Milton Friedman, but the argument I had in mind was that features one might expect to find among your typical intelligent extraterrestrial species include moderate scarcity, variety of talents and needs, material underpinning to other kinds of fulfillment, the fact that people understand their own needs better than they understand their neighbors’ comparable needs, and a danger of corruption when too many economic decisions are made by officials rather than by impersonal (e.g. market) forces. One could imagine a species of whom these things aren’t true, but that would be a feat.
The civil rights in a democracy might be defended partly by the idea that rulers should have an incentive to act in the public interest and partly by the idea that democratic institutions give people an incentive to educate each other. (To get something done you have to persuade people.) Those points seem fairly insensitive to fine points about human nature.
The Bible paints a picture of a law imposed on mankind (or one group) in the face of a very recalcitrant human nature (or nature within that group). It suggests a view that is (NO) verging on (O). I agree that the biblical view is empirically false. There is no God. But lots of views we might want to include in a classification may turn out to conflict with the evidence properly considered.
Namit> But for a given set of facts, utilitarianism admits one right moral response, whereas pluralism can accept many right moral responses.
I want to say yes and no, but that’s a whole nother big topic. Let’s put it off.

Namit,
(I don’t know how to make italics.)
Bill>> [You seem] to want to distinguish between facts of “context” and facts of culture or some other kind of local fact. Are you saying that universalism says morality is responsive to the former and not at all to the latter?
Namit> for a given set of facts, […] pluralism can accept many right moral responses.
I think I don’t understand. One thing I’m pretty sure you don’t mean is that pluralism can hold that in any give circumstance various different actions are morally permissible (one might, for example, contribute to OxFam using the right or left hand). Even the more extreme versions of universalism probably imply *that*, no matter what we mean by “universalism”.
One might think you mean that a pluralist can accept that prima facie conflicting moral claims (that X is wrong, that X is not wrong) can be true of factually identical cases, depending on Y. Y would then have to be no kind of “fact.” Not a cultural fact, not a psychological fact, not a fact about the agent’s beliefs.
I hesitate to think that’s what you mean. Which is why I want to ask again whether by “facts” you mean only some of the facts. Maybe facts external to the agent.
(The point I wanted to postpone was about utilitarianism, and I still want to postpone it.)

Bill,
Going by the categories you provided, I believe there is no O or NO, there is only N. Every moral view (universalist, pluralist, or relativist) derives from and only from human nature. Recall that this was Kant’s great revolution. That mind orders nature, that all judgments about nature arise from the mind. What you consider good for “typical intelligent” extraterrestrials is a product of your mind and imagination (including categories like “typical”, “intelligent”, etc.) and its hierarchy of values (terms like “scarcity”). Moral statements don’t exist outside the human mind (including those we make for another species). We assign value to an idea, and the value is implicitly built upon a view of human nature.
For example, you say that “freedom of expression” is a “pretty good argument” that “doesn’t depend on the fine points of the species”. This statement is false if there is no O or NO, as I believe. The very concept of “freedom of expression” implicitly relies on a view of human nature, as does “pretty good argument”. Think about this!
Regarding the “facts” question in your last post … the idea is that utilitarianism relies on a calculus (maximizing total happiness, say) to determine the moral worth of a decision. Is it right to kill an innocent human if that is the only way to save three other innocent humans? Utilitarianism says yes – it is the only right moral action here. Pluralism can also admit other moral actions as right — those driven by virtue, for instance, or by love, or other subjective motivations — even if it means the death of three humans. (Btw, using the left or right hand is not a morally relevant action, giving to Oxfam is.)
Does it help this time? 🙂 Thanks for the Roerich mention – I gave his work a quick glance and I see what you mean.

I feel like saying again that I agree with pretty much everything in your main post, Namit. My worry is just about the passing reference to human nature in the account of what distinguishes universalism from pluralism.
All that Kant stuff aside, here’s another account of my worry. Your main post seems maybe to suppose that there’s a pretty close connection between how uniform human nature is (how much we humans have naturally in common) and how uniform rights ought to be — and furthermore that everyone sees this. So that pluralists will in fact be people who think human nature isn’t very uniform and universalists will in fact be people who think human nature is very uniform. (And you think human nature just isn’t uniform enough for universalism to be true.)
Whereas I’m proposing that a universalist might have grounds for her universalism that don’t depend on any significantly controversial ideas about human nature. Her disagreement with pluralists or relativists may arise at other points in the argument.

Hi Namit,
To your first three paragraphs — I don’t feel they respond to what I said. We’re probably misunderstanding each other on some really basic point.
On Smith&Smith: It seemed to me that you were saying above that the key reason why utilitarianism is not pluralist is that unlike pluralism, utilitarianism says that in factually identical cases the identical moral statements are true, and pluralism does not. I was trying to understand that. Maybe you weren’t saying that.
On the last point – I agree that some universalists overestimate how much humans have naturally in common. We haven’t disagreed about that.

Peony, I was indeed ignoring your post. Oops.
Peony> just because something is not empirically knowable at this point in time does not mean it doesn’t exist.
I agree. But I think there’s adequate evidence to justify the conclusion that the God of the biblical religions does not exist; also I think in some respects the biblical God is incoherent. I’m not so clear about other conceptions of God – about what they are.
Peony> I also am not too sure that it’s as hard as you suggest to imagine a species where Milton’s principles don’t hold up…
That may be right. I should change my position to this much more modest position: to imagine a species where Millton’s arguments aren’t respectable enough for inclusion in Namit’s taxonomy (which is supposed to include views Namit thinks are plainly false), we’d have to imagine a species whose nature is such that a significant number of them are such that Namit thinks human nature doesn’t allow a human to be that way.
Can anybody tell me how to make italics?
Namit, I don’t really want the conversation to end. (But please ignore this if it doesn’t grab you!) Your view seems to rely on a certain metaethical view that I do not understand. So I wonder: Can you lay it out? And is your taxonomy meant to encompass only the theories of people who agree with your metaethical views?
In your 4:19 comment there’s a passage that I didn’t recognize at first as an argument, but I think it may be an argument: “Moral statements don’t exist outside the human mind (including those we make for another species). We assign value to an idea, and the value is implicitly built upon a view of human nature.”
I’m thinking maybe that’s this argument:
(A) “Moral statements don’t exist outside the human mind”
therefore
(B) “We assign value to an idea”
therefore
(C) “the value is implicitly built upon a view of human nature.”
We failed to get anywhere trying to argue about (C). I propose setting (C) aside and talking about (A) and (B). First question: What do they mean?
My initial reaction to (A) is that I think it probably doesn’t quite capture what you mean. You don’t just mean that the moral views of humans don’t exist outside human minds. If that is exactly what you mean, then I agree (except that I suppose a Martian could come to share some of our moral views, share the same views). People of all metaethical stripes agree with that claim, not only about human moral views but also about human views about every other possible topic. So I think you must mean something a little different.
I don’t understand what you mean by (B). You don’t just mean (B1) “We arrive at moral views.” For (B1) is uncontroversial. And I think you don’t mean (B2) “What’s valuable is just whatever we say is valuable,” because that’s relativism. What, then, do you mean by (B) here?

I’m increasingly regretting my phrase “how uniform human nature is,” and I’m coming to think a focus on the inadequacies of that phrase of mine may be helpful. Here are some proposals:
“Human nature” means whatever virtually all humans have naturally in common (setting aside damaged specimens, tiny-minority mutants, etc; we’re dealing with fuzzy borders here). Thus it’s human nature to have two legs, but it’s not human nature to be male. Human nature is by definition uniform. (But there is plenty of room for disagreement about what features or potentials it includes, or how much variation in resultant characteristics those potentials allow for. Even if human nature turns out to involve only our physical shape, leaving everythign else open, human nature itself would still be uniform. On your view, the underlying dispute between pluralism and universalism is not about whether we all have the same human nature, but rather about how much room human nature leaves for variation in resultant characteristics, from community to community and from neighbor to neighbor.)
Similarly, there is “mammalian nature.” That includes everything mammals have naturally in common. So mammalian nature is part of human nature, as mammalian nature is part of canine nature. And canine nature is part of beagle nature. Beagle nature is canine nature plus some more specific things.
Within the human species, we might also distinguish subgroups, such as males and females. All females have certain things naturally in common, beyond the things they have naturally in common in virtue of being human. So there is a “female nature” that includes human nature plus some more specific things. But as for the group “employees of Google” or “people with dogs,” there is probably nothing they have naturally in common beyond their human nature, so there is probably no more specific nature of those groups.
The “nature” of an individual would include the natures of all the groups-with-natures that she is a member of (assuming she’s not a damaged specimen etc.). But I’m not sure what sense it makes to speak of the nature of an individual beyond that.
Now, when a human has an opinion, Namit, you want to say that it is derived from her human nature. But she also has a mammalian nature and a human-female nature and perhaps more specific natures (say, that of her long-inbred village). I’m wondering why the human group gets a privileged role in view (BC).

Namit, if I understand you, at least part of what you have been doing is answering my last question above about the selection of a group. Here’s how I understand the answer:
When you say every moral view [had by a human] derives from and only from the human mind, what you are saying is that each view derives from the actual set of (mental) characteristics the viewer has, never mind which characteristics are determined by human nature and which are not. And so one might just as well say that each view a human has derives from the actual set of (mental) characteristics she has, never mind which characteristics are determined by her childhood traumas and which are not. That is to say, the notion of a nature (human, mammalian, or otherwise) does not appear in the claim about the roots of views. Therefore the claim about derivation of views does not select any group at all. Therefore it can’t be challenged on its grounds for selection.
Is that it?

Suppose I say
1. Each of my views is derived wholly from my mind.
2. My mind is the sum of its characteristics.
3. Some of those characteristics I acquired before age 30, some not.
I might rephrase this way:
1. Each of my views is derived wholly from my mind.
2a. My mind is the sum of the characteristics it acquired before my age 30 and those it acquired then or after.
Either way, statement 1 cannot be challenged on the grounds of the arbitrariness of the division at 30. For statement 1 does not mention or allude to or rely on that division. If we give names to the two sets of characteristics – the Young ones and the Old ones – then statement 1 simply does not use the notions of Young characteristics and Old characteristics, any more than the generalization “All dogs are pets” uses the concept of beagles.
Your definition of the human mind said it’s the sum of our human-nature (mental) characteristics and the rest of our (mental) characteristics seems analogous to 2a. Which is perfectly true and unobjectionable. Only, its concepts don’t appear in 1.
Does that help?
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I think there’s something a little awkward, though not wrong, about thinking of our characteristics as divided into the human-nature ones and the other ones. I tend to think of human nature (similarly mammalian nature, beagle nature, etc.) as consisting largely of general characteristics or ranges of possibility, and what each human (mammal, beagle) has at any given moment is a set of specific versions of the broad characteristics, a set of positions on the ranges of possibility. It’s not so much that there are two different sets of characteristics, some of which are part of human nature (say, the ones above the neck) and some of which are extra (say, the ones below).
And to say that a certain broad characteristic or range of possibility is part of human nature is not to say that we have the ability at age 50 to move to some other position on that range. We might, but we might not.
But since broad characteristics (bipedality) and specific characteristics (two legs in this shape) are both characteristics, I don’t think I’ve proposed anything that ought to interfere with our discussion above the line.

Yes, it helps to make your point about group selection clear.
However, Bill, the primary purpose of my post where I provided definitions in bold (4:06) was to explain what I mean by “human nature” (the common characteristics of humans, or of subgroups as in male/female)—and the “variable stuff” shaped by genes/culture/experiences. I then continued on to describe how pluralists and universalists view human nature differently, and why they therefore arrive at differing moralities and approaches to human rights. You haven’t told me if this last matter/misunderstanding is now cleared up. If it’s not, tell me why not.

My comment on 10 in the long argument was wrong. What we’d been paying attention to is only the point that 9 doesn’t imply 10.

(The reason I had to add a parenthetical paragaph under V1 and V2 when I introduced them was that my formulae carelessly introduced a weakness that your original formula didn’t have, Namit. Sorry.)

This is a revised version of a long comment I submitted a little earlier, which Namit may have deleted by now.
Thanks Namit!
A-second. Your answer is “That is what I mean.” i.e., you “include in a person’s ‘human nature’ not just the characteristics she has in common with all other humans, but also the characteristics she has in common with e.g. all other humans of her gender but not all other humans.”
So you are saying the fact that a feature is part of human nature does not mean that it is common to all humans (naturally or otherwise). That seems to disagree with your answer to my A-first:
A-first. I think you are agreeing with this statement of mine: “I’d want to identify human nature with the what people have naturally in common.”
If your answer to A-second captures your view, then you don’t think “human nature” is the same as what we have in common or what we have naturally in common, so it would seem that the concept “human nature” doesn’t appear in the main point at issue between us, which is about how similar a universalist has to think all people are, or naturally are.
A-third: on steering clear of bipedality. I’m happy to steer clear of bipedality in particular. That you want to steer clear of bipedality comforts me on one point: how fine-grained are the rights we’re talking about? The finer the grain, the harder it is to be a universalist. When you say bipedality is completely irrelevant that tells me you think rights to ramps and elevators are not under discussion at all. Too fine-grained, I suppose. That makes it easier to be a universalist.
What I don’t want to do is make assumptions about what aspect of human nature is going to be relevant. I don’t think there’s a sharp line in nature between mental and other characteristics, and I don’t think mental characteristics are the only morally relevant ones.
__________
B. The (a)(b)(c) is, I think, the same as what we’re talking about in B(iii), so I’ll answer there.
You had indeed told me that in your view it is impossible to arrive at Millton’s conclusion (a certain set of universal rights) on the basis of arguments like his, and you had suggested arguments for that (see (i)-(iii)). But you haven’t pointed to any internal flaw in Millton’s arguments. Of course, I gave the arguments in only the sketchiest allusive way. Anyway I’m happy to keep Millton on the sidelines for now.
For convenience let’s identify the ultimate point at issue as CU: the Conclusion about Universality, which is this: “A universalist has to think people are more similar than NA.”
B(i). “I would have instead said “(A) and (BC)”. –So you’re saying there’s no argument in that passage. That leaves me with (ii) and (iii) as arguments for CU. I still don’t understand what you mean by statement (A).
B(ii). What I was doing in B(i)(ii)(iii) was trying to address everything that looked like an argument that you had presented for CU. Originally you offered the principle DHN, about derivation of beliefs from human nature.
I had thought of one line of thought from DHN to CU. So I laid that out in ten steps and criticized it (basically recapping my early Kanty comment).
Later you refined DHN to DHM, about derivation of beliefs from the features of the believer. If there is an argument that starts from DHM and ends with CU, I would love to consider it. You’re right that I didn’t discuss an argument like that above. I haven’t thought of one yet.
So I think it is fair to say that the only arguments on the table for CU are the one in (iii), which you present now as (a)(b)(c), and possibly the new percentage argument. I’ll talk about the percentage argument first.
__________
Percentage Argument. I don’t understand the details, especially in 5, as I describe below. But from what I can see the argument seems to be aimed at establishing the point that two people can be universalists while believing in different rights. I agree with that point. The percentage argument doesn’t seem to be aimed at establishing CU, and it doesn’t seem to be arguing for V2 (which would support CU).
So I think the only argument on the table for CU is the one in (iii), aka (a)(b)(c). But before we go there, here are my thoughts on some details of the percentage argument.
I agree with 3 and 4, but I don’t understand 5.
In 5, I don’t understand the first sentence: “What will make Mr a universalist is that he thinks the same set of characteristics comprise the 70% common part for all.”
In this sentence, it seems to me that either (UU) you’re stipulating that anyone who believes in 70% is a universalist and you’re talking about why, or (UP) you’re allowing that perhaps only some people who believe in 70% are universalists, and you’re saying what kind of person who believes in 70% is a universalist.
If it’s (UP), then I want to mention that I think (UP) conflicts with V2 (which I reject).
But no matter whether it’s (UU) or (UP), I don’t understand the explanation given: “What will make Mr a universalist is that he thinks the same set of characteristics comprise the 70% common part for all.”
I ask myself whether by “same” you mean “same [as Ms thinks].” In other words, I ask myself whether what you are talking about here is whether Mr agrees with other people about which characteristics are the 70% we have in common.
A reason to think that is not what you mean is that it doesn’t seem relevant to (UU) or (UP).
A reason to think that is what you mean is that you seem to be talking about that sort of thing later in 5.
Another reason to think that is what you mean is that the alternative reading doesn’t make sense. The alternative reading would be that you mean Mr thinks not only that (a) you and I have 70% of our chararacteristics in common, but also and crucially (b) your 70% are going to be the same characteristics as my 70%. While in fact (b) doesn’t add anything to (a).
I’m a little confused about the rest of 5 too. It sort of looks like you might be saying that a 70%er like Mr can’t be a real universalist after all, but can only be a universalist about some rights, because he doesn’t think all humans are exactly alike (100%). But I don’t think it’s your view that a universalist has to think everyone is exactly alike.
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Regarding (iii) – (a)(b)(c): This is basically “V2, therefore CU.” And I agree that if V2 is true CU is true. (I think my 2:41 “Ooh” objection is wrong because V2 along with the fact that Namit is not a universalist does in fact yield CU.) So we’re left with the question whether V2 is true. Here’s one argument against V2.
Suppose I have a view of how widely people can vary, and I am to develop a conception of what rights should be enforced. That’s a tall intellectual order. I’ll have to think about the nature of law and the nature of morality, and how they differ from custom and coercion and other kin; and I’ll have to have a view about how legal and moral statements can be rationally justified. Further, in thinking about freedom of religion I’ll have to think about how religion works as an anthropological phenomenon and I may have to think about whether there is adequate reason to think God will condemn people or societies that reject view X. In thinking about voting rights I’ll have to think about how different kinds of institution work. In thinking about freedom of the press I’ll have to think about the arguments for different kinds of restriction: libel, state secrets, racism, etc. etc.; and I’ll have to have a view about whether civilization depends on the enforcement of certain key beliefs (about honesty, filial piety, Hell, sexuality, what have you). In thinking about the right to life I’ll have to think about the fetus. In thinking about rights for court procedure (e.g. the US Bill of Rights ##5-7) I’ll have to think about the sociology and psychology of the weird process that is court proceedings, according to any number of different institutional rules. And so on. And I’ll have to construct long complex arguments on all these matters.
Now, (Z1) these matters (topics other than the degree of variability in the feaures of individuals) are all so complicated that a reasonable person might make a mistake at some one point: on a particular fact, a generalization, or the structure of a line of thought. A reasonable person might make many such mistakes. Really I think what’s so unlikely as to be not worth considering is that someone would get everything more or less right.
Therefore, (Z2) two people who have the same view of how similar human individuals are (or even the same view about what our similarities are) can reasonably arrive at different views about how similar our rights should be, because they can make different mistakes on the various kinds of points described above.
Therefore V2 is false.

Hi Namit, I think that really helps.
A-first and second.
Namit> The notion is that the view of “what’s naturally common for a group” is paramount to what set of rights one might consider applicable for that group. Agree?
I agree to adopt that understanding of CU, but I disagree with that proposition. For one thing, the rights of a group within a society are going to be rights against people who are outside the group, so we’re talking about institutions involving parties outside the group.
A-third:
Namit> rigorously speaking, all human characteristics are mental.
I disagree, but I think we both agree on putting this debate aside.
_____________________________
On whether V2 implies CU, and specifically my argument against V2:
Namit> I think the use of “right” is misplaced (what can “right” and “mistake” mean here? – there are only views). A term I think might work better is “prescriptions for social life (PSL)”
I agree that there’s a profound set of problems here about whether moral beliefs are the kinds of things that can be true or false, or should instead be seen as mere prescriptions (not as the belief that such-and-such is the right prescription), though I think that insofar as we call them beliefs or views, we’re buying into the “true” and “false” language. Instead of views about rights, I’m happy to say prescriptions about rights: PR.
Namit> Z1 is about the likelihood of an individual getting this choice [of a social morality and associated institutions] “right”.
Well, I meant people can make mistakes in their reasons for their PRs, and they can make different mistakes without having different views about the degree of human variability. I said I thought people would almost certainly make mistakes in their reasons, but the important point was that it is possible for people to end up with different conclusions. Whether either of the conclusions was right didn’t matter to my argument.
The mistakes might be on factual matters such as the likelihood of juror corruption or the existence of Zeus, or on structural matters such as reversing the arrow of an implication in a logical argument.
I could have argued for that same point – that people could end up with different PRs though they had the same view on human variability – without making any reference to mistakes. It’s possible for two reasonable people who have the same view about human variability to diverge in other aspects of their reasons for their PRs, such as the aspects I listed. Therefore V2 is false. (Though on such complex matters I think full-blooded mistakes are as common as rain.)
Namit> However, the key question now is, can two people who have very dissimilar PSL have a similar view of human nature? Are these two things wholly independent, or is there a positive correlation? This isn’t as clear cut to me. Whether V2 is false depends on this question (showing a positive correlation is all we need to show V2 true).
Well, I think PSLs include PRs. And I think PRs and the other parts of PSLs are commonly grounded not just in views about what qualities human individuals have, but also in further facts and lines of thought, and that people can diverge in these latter respects without diverging in their views about individual variability.
I think maybe the basic disagreement between us is that I think a taxonomy for filing incompatible views like relativism, pluralism (sic, sorry), and universalism, has to allow for mistaken views. And then one can’t say a view doesn’t belong in the taxonomy at all because something has gone wrong in the basis for it. So I think if someone sincerely says “I think everyone has [or: should have] the same rights!” and she has no definite opinion about human variability, and she is confused about what in particular our rights are, she should probably be classed as a “universalist.”

Namit, I agree completely! So it’s like what you said about Abrahamics and scientistics versus romantics and postmodernists: a useful generalization.