Hi Alan, you raise some points of concern I share about the future.
It's plausible that a fair fraction of the computing resources of civilizations are devoted to suffering. This could be true if suffering is computationally productive (e.g., sentient reinforcement-learning algorithms?) or if civilizations do scientific research using conscious simulations. So future human computational resources could be a cause for concern; however, other civilizations might run suffering computations as well (perhaps in vast quantities?), so it's possible that humans could prevent lots of suffering by trading with other civilizations, providing resources which are cheap for humans to create in return for fewer suffering computations run by the ETs.
The second point strikes me as speculative. Given the vast time and space scales that would probably seperate us from other civilizations, it's hard to imagine an overlap of states in technological progress that would allow for meaningful trade between us and them. Alien wildlife or significantly more or less advanced civilizations seem to be more plausible reasons for concern.
As for computationally productive suffering, I'm reminded of Robin Hanson's em revolution scenario and his projection of a resulting economic race to the bottom where ems live at near-subsistence with high workloads. To my mind, the crucial question in any such scenario (sentient mass computation for productivity) is how much of this process can be driven by carrots, and how much really needs sticks. If David Pearce is right about his premise that the adaptive functions of suffering can be replaced by "gradients of bliss", i.e. differential hedonic states within a purely positive state-space, then there is no good reason why a civilization should opt for the sticks - with the exception of pre-committing to torture as a game-threoretic weapon in conflicts. Unfortunately, this weapon has been used abundandly by humans so far and it could reach a very large scale in a post-human future.
In the present, habitat loss prevents existence for wild animals that would have lived in those environments. And as humans grow in technological sophistication, they may destroy nature entirely in order to harness its resources for computation or other uses.
Right. It is surprising how underrepresented the meme for ethical ecosystem replacement/redesign is. When I mention it, people usually react as if I were motivated by maliciousness toward wild animals, or they are really surprised that anyone would question the ethical legitimacy of the natural status quo. Talks of "Mother Nature" and "Her" (!) alleged wisdom and benevolence are unfortunately widespread. Rational analyses like yours are frustratingly rare. Otoh, habitat loss also correlates with reduced sustainability of civilization, which is only good if a (post-)human future is very bad.
As for vegan outreach, merely trying to convince people of veganism is not sufficient imho. Awareness raising is highly relevant of course, but I think that in order to gain statistical grounds realistically, we really need to push hard for research and development of sustainable, cheap, healthy, high quality alternatives. Soy is not the (only) answer, and malnutrition doesn't convince majorities. In-vitro meat could be a solution, but maybe not the only one - if we could devolop an integrated process that could start with a biological substrate like tube-farmed algae, process it to derive proteins and other nutritional building blocks, and then create food products like eggs, meat etc. out of 3D-printers with virtually indistinguishable properties from the original animal products, we could phase out the whole paradigm of industrial animal use within decades. Once a proof of concept of this idea exists, if it is sustainable and economically competitive, that's
when majorities will accept the ethical relevance of veganism. At that point, democracies could accept a complete ban of using sentient beings as physical/industrial resources for the first time in all of history. Before such alternatives exist, it will inevitably be rationalized by majorities of voters and consumers. The public discussion of animal rights and veg*anism has been too absorbed with consumer guilt vs. signals of moral superiority; it puts people off and it distracts from a rational analysis of the solution space.
Another worthwhile goal may be a scientific near-term estimate on how realistic hedonic enhancement is, and what its side-effects probably are. Understanding the brain, and how it represents affect, seem to be at the core of this question. One could take specific scientific hypotheses and work from there in the relatively short term. For instance, how strongly is compassion contingent upon the ability to suffer oneself? Does a reduced pain sensitivity automatically lead to a reduced level of compassion with the pain of others? If so, are there exceptions, and on what principles do they rely? I think this is relevant in order to prevent hedonic enhancement to create a generation of discompassionate people who can't understand why suffering is bad.
Additionally, the "gradients of well-being" feasibility hypothesis could be examined by taking specific aversive functions associated with suffering, and modelling solutions that would express them as positive gradients. For instance, the agony of suffocation, a very specific experience of negative affect in a very specific functional context, could be modelled in detail neurologically and information-theoretically. From this starting model, one could search for possible alternative implementations that would implement the same function by creating a strong lust for breathing (rather than a desperate need for it) under the specific conditions of suffocation. In other words, brain modules associated with desire and pleasure could be used to motivate breathing when blood oxygen is low, instead of the brain modules that currently give it negative affect. Whether this can be done in principle, and whether there is an information-theoretic difference in the general affective valence between the two implementations are extremely crucial empirical questions for hedonic enhancement, and I think they can investigated by neuroscience, again within a few decades.
It may make sense to push awareness of these specific questions into the public, scientific and political meme spheres.