Exploring Invertebrate Sentience and its Moral Implications

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Impartialist Sentientism and Existential Anxiety about Moral Circle Explosion, published by Rafael Ruiz on June 22, 2024 on The Effective Altruism Forum.
Background: I'm currently writing a PhD in moral philosophy on the topic of moral progress and moral circle expansion (you can read a bit about it here and here). I recently was at three EA-related conferences: EA Global London 2024, a workshop on AI, Animals, and Digital Minds at the London School of Economics, and the Oxford Workshop on Global Priorities Research.
Particularly this year, I learned a lot and was mostly shaken up by the topics of invertebrate welfare and AI sentience, which are the focus of this post. I warn you, the ethics are going to get weird.
Introduction.
This is post is a combination of academic philosophy and a more personal reflection on the anxious, dizzying existential crisis I'm facing recently, due to the weight of suffering that I believe might be contained in the universe, which I believe is morally and overwhelmingly important, and for which I feel mostly powerless about. It is a mix of philosophical ideas and a personal, subjective experience trying to digest very radical changes to my view of the world.
The post will be as follows. First, I explain my moral view: classical utilitarianism, which you could also call impartialist sentientism. Then I broaden and weaken the view, and explain that even if you don't subscribe to this moral view, you should still worry about these things. The next section very briefly explains the empirical case for invertebrate and AI sentience.
Although I'm riddled with uncertainty, I think it is likely that some invertebrate species are sentient, and that future AIs could be sentient. This combines in weird ways with moral impartiality and longtermism, since I don't think it matters where and when this happens, they're still morally weighty.
This worry then explodes into moral concern about very weird topics: astronomical numbers of alien invertebrate welfare across the universe, and astronomical numbers of sentient AI developed by either us in the future or aliens, and other very weird topics that I find hard to grasp.
I talk about these topics in a more personal way, particularly ideas of alienation and anxiety over these topics. Then I worry about potential avenues of where this "train to crazy town" is headed, such as: blowing up the universe, extreme moral offsetting by spreading certain invertebrate species across the universe, tiling the universe with hedonium, infinite ethics, and worries about Pascal's Mugging.
Then I take a step back, compose myself, and get back to work. How should these ideas change how we ought to act, in terms of charitable donations, or lines of research and work? What are some actionable points?
Finally, I recommend some readings if you're interested in these topics, since there's a lot of research coming up on this topic. I conclude that the future of normative ethics will be very weird.
Impartialist Sentientism.
Currently, the moral theory I place the highest credence on is total hedonist utilitarianism (what you would call classical, Singerite, or Benthamite utilitarianism), but I believe a lot of these arguments go through even if you aren't, because the amount of value posited by impartialist hedonist utilitarianism tends to trump other considerations, among other things. Just in case you're not up to speed with moral philosophy, let me give a broad background overview on the moral philosophy.
If you're well acquainted, feel free to skip to the next section.
This theory breaks down into the following elements:
By "pain" or "suffering" I mean "any negatively valenced experience", that is, any experience judged to be negative by the subject undergoing it. By "pleasure" or "happiness" I mean "any positively valenced ex...