Many good points.
Moral uncertainty doesn't give you what you want. It gives you everything and nothing. You don't use it to question your own values, but only as a rhetorical device to get other people to question their values, and only those that disagree with your current values. Maybe the Logic of the Larder goes through. Maybe animal farming is good for wild animals. Maybe animal suffering is intrinsically morally good. You can't point to uncertainty to privilege your current moral preference.
The costs to slaughterhouse workers are internalized by the voluntary nature of slaughterhouse work. People make mistakes but by and large you have to pay them to compensate for risk and unpleasantness in the workplace, or else they'll find a different job.
I didn't know about the crime rates near slaughterhouses. A possible hypothesis might be that sociopaths or people with a penchant for violence are more likely to work in slaughterhouses, due to the violent nature of the work. If they also live nearer, this could explain the difference. If so, these people might commit crimes elsewhere in a world without slaughterhouses. But I'm only speculating.
Health and environmental effects are probably good arguments. It would have been better for us all if China had banned live markets in 2017. However, the unhealthy nature of overeating animal products are internalized also. No one is forced to eat more meat than is good for them. The current vegan substitutes aren't healthy either. Too much soy can cause infertility, to name just one example.
I do want to spite animal advocates. I didn't appreciate that they declared I should have human rights only if I support chicken rights. This was after they advocated bans on animal products even though we have no good substitutes. In fairness to the EA movement, this hasn't happened here, but it did happen. This was the exact opposite of "gains from trade through compromise" and "cooperating with other value systems". My response to it is to boycott their ideological goals.
My general observation is that animal rights advocates feel morally superior to omnivores, and expect the world to treat them accordingly. It virtually never occurs to them that other people simply don't share their pro-animal preferences, and if they want us to forgo consumer surplus, they have to compensate us for that. You're free to produce vegan food as a non-profit and sell it at cost, if you want to shift the indifference curves of omnivores.
I don't intrinsically care about the suffering of others. I just want to live in a society that leaves me alone, according to norms that we don't have to harass, backstab and torture each other. That requires human rights (or something functionally equivalent like trustworthy alliances). I don't see what chicken rights can possibly do for this end. Looking at the statements of animal activists, all it did was make them more hostile to omnivores.
"Why would you prefer real meat over fake meat, even if they were indistinguishable and had the same price?"
Why wouldn't I? I don't believe in animal rights. Perhaps if no animal rights activists had ever condoned human rights violations against me, I might be indifferent. But they did, and the substitutes won't be indistinguishable during my lifetime anyway.
"This would mean our obligations to conscious and suffering non-person (and not future-person) humans are only (or primarily) indirect, circumstantial and sometimes completely absent, because what we owe them for their own sake is dominated by what's owed to human persons."
I have a hard time imagining conscious suffering non-person humans. But yeah, I do believe that if you were never a person, will never be a person and aren't a person, I don't need to respect your rights. What would the point be? Human rights are a coordination tool for humans to benefit humans, and even that's not really working very well.
"I think that black markets will be rare if the substitutes are close enough. Few people would accept the risks of going to the black market in the long-term just for authenticity. At least cocaine offers a different kind of experience from what's legal to buy."
I don't know. Alcohol is legal and people still buy the illegal marihuana.
"I think the share could be brought up past 99%"
Not in your lifetime. I think you're underestimating how culturally entrenched (animal) meat production and consumption is. It's common for vegans to think incorrectly that other people also don't care (much) about meat.
What do you think of the concept that suffering and pleasure are the same phenomenon, except "sign-flipped", i.e. the same neurological/computational principle gives valence to both suffering and pleasure? If so, you could "reduce intense suffering" by creating intense pleasure. This is probably not your goal, but is there a principled philosophical or neuroscientific reason against this view?
Empirically, I think it's pretty clear that most people are willing to trade off pleasure and pain for themselves. (They also want things other than pleasure-seeking and pain-avoidance.)
The question why people don't discuss values has perhaps a cynical answer. Most people don't have coherent, formal values, they just want to look good, show group affiliations and feel good about themselves. This creates an additional burden for suffering-focused views because they focus on a negative, which puts a burden on people who want to look caring (if no one raises the issue of suffering, no one has to feel empathy or signal that they are compassionate by addressing it). Most people don't want to suffer (much), but they care much less about the suffering of others, for obvious evolutionary reasons. It's also hard to tell a positive success story about suffering, or to create positive motivational goals, because unless you count pleasure as "negative suffering", the best win you can have is the absence of something, so you're not doing better than dead people, intergalactic voids or lifeless asteroids. It's hard to frame that into a motivational story about heroic victory.
"Do you see this being true even if/when humans colonize space? (You and I might be long dead by then.)"
Technically yes, because there will still be animal farming on Earth. What happens in a very far future post-human civilization of course, is speculative.
"Would you still insist even if you couldn't tell the alternatives from the real thing and enjoyed them as much (under blind test), and they had the same or better nutritional quality? Why?"
This depends on the price, I would say. If it's also 50% cheaper, I would probably come around. As for why, because I prefer real meat over fake meat. I also don't expect it to be indistinguishable during my lifetime. Also some animal rights activists have condoned human rights violations against my person for disagreeing with veganism.
Philosophically, I think human rights are for human persons and nonhuman animals don't qualify. If we ever have intelligent entities who are people but not human, we can extend our definition to them. No one who can participate in this discussion will ever be a nonhuman animal. Coordinating to respect human rights is hard and costly enough; extending it to chickens is nonsensical. We have no obligation to be utilitarians, and even they probably have better things to do than get the meat consumption down to literally 0%.
"Also, we only need enough people to want to ban animal farming and animal products, not for everyone to oppose them. There might still be a market in them if/when that happens, but it would be a black market, so I'd guess at most a few percent of the total market wherever there are bans."
Yes, and also you have to have the political capital to ban it, which isn't free, and the black markets will have further costs like mafia bosses killing people to secure their illegal meat infrastructure, like we have now with cocaine. You'd have a War on Meat akin to the War on Drugs. Much easier and cheaper for governments to tax meat rather than ban it. But even when you ban it, you won't have 100% market share for the substitutes.
Alternatively, you could use the scientific method to design artificial sentient systems with high welfare output per resource input and harvest the ecosystem's production to power these. Or even better, use them to maximize human welfare because we're all human.
I'm not a utilitarian, but if I were, I would emphasize quality over quantity. There are two ways in which quantity can harm quality. The first is when there's a trade-off and spending resources on quantity causes you to spend fewer resources on quality. So if you spend money and attention on implementing panspermia, you can't spend the same money and attention on improving the quality of life of sentient systems. The second is even worse: On those margins where quality is negative, quantity actively hurts the total. So you had better be really sure that the quality is positive before you spend resources on quantity. In the context of panspermia, I'd worry about the suffering and preference-frustration that will be caused by the project.
I'm not a utilitarian, however, so I wouldn't donate to such a project either way.
Then that's begging the question. The Alienation Objection isn't to Act Consequentialism at all, but to taking impartiality for granted.
Why does Act Consequentialism imply impartiality?
The definition used here ("according to which (very roughly) you should do whatever has the best consequences, i.e., whatever produces the most value in the world") punts all the complexity into the definition of "value in the world", but that is entirely subjective and can be completely partial, as it is for many if not most people.
It seems this entire discussion is suffering from the confusion of Act Consequentialism with something more specific and impartial like a version of Utilitarianism. Or at the very least an underdefined use of terms like "value in the world".
" I think it's often not so easy for people to just leave their job and find another, especially if they have children to take care of. "
Yes, elasticity isn't absolute, but in the long run it matters a lot. In the extreme, you can walk out and be jobless rather than accepting bad conditions. That alone puts a cap on how bad conditions can be, although perhaps some risks can be hard to estimate.
" Do you care about others or their wellbeing for their own sake at all for any other reason? "
Yes, if I have positive personal relationships with them or they have earned it. However, I also do the negative version (revenge), and in many cases I find that more motivating. So there's no benevolence bias on my end. I have yet to find a philosophical reason why I should have one.
Thanks for the interesting discussion, I'll end it at this point.