Some people aren't intelligent enough/don't have high enough time preferences to function in modern society.

Why should we have a moral expectation that people have to "function in modern society" or else be enslaved/institutionalized? Our adaptive environment is small forager tribes, not "modern society".

I fail to see how men having only recently gotten the vote is a good argument against women getting the vote.

You neglected to include a good argument in favor of slavery.

If you look at my earlier post, and my examples in this post, you'll see that "altruistic deception" is when you present something that is false and unworkable in order to motivate people to do work that you hope will contribute to a real solution. Your objection amounts to saying that we can't say that anything is false, or even that one X is more false than another X.

Let's test your idea that "There are no good arguments for X" is simply how having a successful social taboo against X feels from inside:

"There are no good arguments for the phlogiston theory of chemistry" is simply how having a successful social taboo against the phlogiston theory of chemistry feels from inside.

"There are no good arguments for Ptolemaic astronomy" is simply how having a successful social taboo against Ptolemaic astronomy feels from inside.

"There are no good arguments for Aristotelian physics" is simply how having a successful social taboo against Aristotelian physics feels from inside.

Marxism is less able to make correct predictions, and more thoroughly empirically refuted, than any of those theories. It is a false theory. It is a not-even-wrong theory. If you ask a Marxist to predict whether a corn blight will make the price of corn go up or down, he can only say, "Markets are a tool of the bourgeois, and their prices are commodity fetishization." Marx deliberately removed the concept of market price from the Marxist ontology, so Marxists can't be tempted to make quantitative predictions and be proven wrong.

Christianity, my other example, is also bad at making predictions. I object to your implication that we cannot say that the theory of Christianity is less probable than the theory of evolution.

Yes they did, in particular the false claim that there are no significant diffrences between blacks and whites.

That's false. The abolition movement never claimed there were no significant differences between blacks and whites. Read the transcripts/summaries of the Lincoln / Douglas debates.

I had in mind lies that were intended to be acted on, to further my cause.

For instance, suppose my cause is to prevent the growth of a hole in the ozone layer. I tell people they must stop using CFCs. Actually it would be enough to limit the use of CFCs below some sustainable limit. But not everyone is going to listen to me, and I need to offset their CFC-use with even lower levels of usage from my followers. So I lie to my followers and tell them everyone in the world must stop using CFCs absolutely for the ozone hole to mend. That's a lie I want them to act on.

There are other kinds of reasons why one might lie in the service of a cause, where my logic doesn't hold. For instance, suppose my cause is to win a war. I need to convince my people to keep fighting and not accept the enemy's armistice terms. So I lie to them, saying the enemy is building a magical doomsday weapon that can strike our people from afar, and only taking over the enemy's lands can prevent its construction. After we win the war, my people torture and kill many of the enemy population because they refuse to reveal the location of the doomsday weapon I made up.

In this case, I didn't want people to actually act on the lie; I just wanted its side effect of making them fight in my war.

There are other cases. For example, the main supporters of my cause happen to come from the Purple Tribe, whose religion says the germ theory of disease is false. I know they're wrong, but to gain their support for my cause, I must lie and publicly say they are right. Then they help me win my cause, while I help them stop effective disease prevention measures - a successful alliance.

There were good arguments for all of those things when they were still in use. There are no good Arguments today for favoring Aristotelian physics over Newtonian physics, Ptolemaic over Copernican, or the phlogiston theory over the oxygen theory, where an Argument means a complete consideration of the evidence and the individual arguments.

Viliam's comment, which I'm sad to see has 10 points on LessWrong, uses the impreciseness of what I meant when I said "no good arguments" to crowbar in a claim that we just can't say some theories are wrong. We can.

It should be obvious to anybody reading my original post that digressions into what is a "good argument" are irrelevant; the point is that many activists motivate people by advocating ideas that are false, or deceptively one-sided to the point that they are lies of omission. My question is what the distribution of the degree of necessary lying is as a function of a cause's social utility.

I think you're misunderstanding Viliam's point. Your examples, other than Marxism, aren't proposing empirically testable theories: they're moral revolutions, or social ones that demand valuing some people differently from before. Slavery, suffrage, Christianity or Prohibition aren't right or wrong in some objective non-moral sense. Arguments for or against such things are inevitably about convincing people, not about some objective truth.

I fail to see how men having only recently gotten the vote is a good argument against women getting the vote.

You neglected to include a good argument in favor of slavery.

If you look at my earlier post, and my examples in this post, you'll see that "altruistic deception" is when you present something that is false and unworkable in order to motivate people to do work that you hope will contribute to a real solution. Your objection amounts to saying that we can't say that anything is false, or even that one X is more false than another X.

Let's test your idea that "There are no good arguments for X" is simply how having a successful social taboo against X feels from inside:

"There are no good arguments for the phlogiston theory of chemistry" is simply how having a successful social taboo against the phlogiston theory of chemistry feels from inside.

"There are no good arguments for Ptolemaic astronomy" is simply how having a successful social taboo against Ptolemaic astronomy feels from inside.

"There are no good arguments for Aristotelian physics" is simply how having a successful social taboo against Aristotelian physics feels from inside.

Marxism is less able to make correct predictions, and more thoroughly empirically refuted, than any of those theories. It is a false theory. It is a not-even-wrong theory. If you ask a Marxist to predict whether a corn blight will make the price of corn go up or down, he can only say, "Markets are a tool of the bourgeois, and their prices are commodity fetishization." Marx deliberately removed the concept of market price from the Marxist ontology, so Marxists can't be tempted to make quantitative predictions and be proven wrong.

Christianity, my other example, is also bad at making predictions. I object to your implication that we cannot say that the theory of Christianity is less probable than the theory of evolution.

If you're backing a cause which doesn't inspire the action you think it deserves, and you find yourself twisting the truth a bit for dramatic effect, how strong evidence is that that your cause is less worthy than you think it is? Can you give examples where you would go ahead and twist the truth anyway?

Ideally, I would estimate the negative effects: how many people would later learn I lied and abandon my cause, and how enemies of the cause might use the fact I lied against it, and the reputational harm to my other causes and to my allies.

To stop me from lying, a moral theory that says lying is wrong for me as a person would have to give this greater weight than some non-negligible factor in the success of a cause which could drastically affect millions of people for the better, e.g. Abolition.

Those movements didn't require wholesale lying and sleight-of-hand, because they could make valid and true one-sided arguments.

Yes they did, in particular the false claim that there are no significant diffrences between blacks and whites.

It's hard to come up with a good counter-argument to "slavery is bad".

Well, "slavery is bad" isn't even an argument it's either an asertion or at best a value judgement. The fact that this wasn't obvious to you is a sign you haven't thought much about the topic.

Even women's suffrage and Prohibition didn't require lying.

Well, consider how the latter turned out. Prohibition involved making false statements (they might not technichally have been lies only because some of the people making them believe them) about how much of the contry's crime was caused by alcohol. Some counties even sold off their jails after prohibition passed, figuring that without alcohol there'd be no crime so there would be no need for it.

What might be the cause of the perceived difference between the atheists/nontheists in Europe and in the USA?

I have the general feeling that the average atheist in the USA, when asked about religion, will be very open about believing religion to be either evil or ridiculously stupid, and will make at least a few remarks about how idiot those lunatics must be who believe that there are invisible people living on the top of the clouds. On the other hand, in Europe you are more likely to hear that "well, I'm not very religious", but many would culturally still identify as a Christian, and will held marriages, child naming ceremonies, funerals etc. in a church, and might even rarely, but occasionally go to church on a bigger festival (like Christmas) because it looks or feels nice.

I wonder why. I know much more Europeans than Americans, so it might be that the louder voices are better heard from a group I have less contact with, or it might be that because in the USA the Christian fundamentalists are louder than in Europe, so the atheist fundamentalists are also louder.

I'm fully aware that I based this observation mostly on people I have contact with, and in at least a small part being influenced by popular culture, but I don't know of any exhaustive research or survey comparing the cultural standpoint of nontheists specifically regarding the differences between Europe and the USA.