I feel like there's a better version of this to be written, but this is what I have so far.
17 February 2021: Made improvements.
6 May 2021: this is an important addendum relating to how a person should pray to God as presented by the metaphysical organism argument.
Let's say you are an effective altruist (an EA), looking to understand reality so as to best be able to do good. It turns out that we have theoretical reasons for believing a certain mysterious sea creature lives under the ocean. We also have many, but not 100% conclusive, sightings of that sea creature. Otherwise we might think that its part of the abyssal plain is uninhabited, and store nuclear waste there. But if it does exist, it will suffer greatly from the pollution.
Ordinarily, an EA might do something like say "Let's come up with some subjective probability estimates -- maybe 60% there is a sea creature, 40% there isn't" and then use that in weighing whether or not to store the nuclear waste there. Maybe we fear that the sea creature could suffer -100,000 utils if we put the waste there. But in another part of the abyssal plain, there is another possible sea creature that could suffer -100,000 utils. We could multiply the likelihood of a sea creature existing by its level of expected suffering to determine in which part of the abyssal plain to store the nuclear waste (or maybe we just decide not to store the nuclear waste under the ocean at all). A possible sea creature can have a significant effect on policy.
I want to consider a metaphysical creature (although, technically, "creature" may be the wrong word, "organism" may be better), which we have good theoretical reasons to think might exist, and of which we also have many sightings, which at least up until now have not been considered 100% conclusive by the epistemic mainstream. I will focus on the theoretical reasons for thinking the organism might exist, and on practical outcomes of taking into account this possibility.
A "metaphysical organism" is simply one which goes beyond physics. Why should we think that there is something beyond physics? When we look at observed reality, we realize that there is such a thing as perceptions of matter, and such a thing as consciousness. We can suppose that really, everything that is is matter, and then consciousness arises out of that. Or we can suppose that everything that is is consciousness, and we simply have perceptions of matter. Or we can suppose that there is such a thing as matter, and consciousness, and the two interact.
It's hard to imagine how matter and consciousness could interact, because they are so different from each other. It's also hard to imagine how consciousness could arise from matter. What's easy to imagine is that we perceive matter -- we are consciousness and consciousness can interact with consciousness.
If I am going to be a philosopher, or an empiricist (someone who examines experience), then all that exists is my stream of consciousness. And yet I observe that there are things which do not follow from me, and so there is some other reality at play than my own. So I am just a bubble of experience, or an experience-body. But I somehow touch other experiences. I change things in my experience-body because I prefer them to be different and I act on that preference. In the way in which I am conscious, I have preferences and act. I will changes in my experience-body. I am consciousness and I will changes. Consciousness acts by willing. So whatever it is that modifies my experience-body apart from me, is something that willed that change.
How would such a being, or such beings, connect with me? We could try to use a physical metaphor: an experience-body is like a sphere, and when the surfaces of two spheres touch, there is a connection. But that's using a physical metaphor. If we only use experience-language, it seems most natural to think that when the spheres overlap, what's really happening is that one being experiences exactly what the other one does -- not a copy, but the very same experience. We don't observe ourselves doing this with any other sentient beings. We have experiences that are broadly analogous with those of other sentient beings, but certainly not the exact same. We experience metaphorical copies of what other beings experience.
So then, how do we connect with people? According to the Metaphysical Organism view, there's some other being that really does connect with each of us, who "serves" reality to each of us. This being is the Metaphysical Organism.
Without resorting to some things I've mentioned in other texts (simantism, legitimism), which may be able to specify that the Metaphysical Organism view is more or less the only one, there are other possibilities. It's possible to also believe in many, many beings, who create a web of these shared experiences. Under this view, my experience body is shared by many other beings, likely each only experiencing part of my experiences. Except, when I fall asleep at night, I cease to exist, yet when I wake up in the morning, I am in many striking ways similar to the being who fell asleep the night before. So it seems like there is some being who watches my experience closely enough to recreate me each morning. Or some organization of beings who work together very closely to bring me back each morning in continuity with who I was before? Likewise, reality operates marvelously consistently, as we see with the viability of the natural sciences in knowing the world. It seems likely that if there are many metaphysical organisms (beings known through metaphysics rather than by sight), they are better organized than humans are, and their coordination is striking. How do many consciousnesses become one? By sharing consciousness with each other, or even by one consciousness containing all others, like a TV director whose visual consciousness includes all the visible monitors showing different camera angles. You could see the many consciousnesses being on one end of a spectrum of "manyness vs. oneness", and as they become better connected and organized, the more they become like the one Metaphysical Organism at the other end of the spectrum.
It may be more clear to ask, is there one "server" of conscious connection or many / a "peer-to-peer" network? (Or to say that the question is, "Berkeleianism" (one server) "or a kind of panpsychism?" (many / peer to peer).) Let's suppose that we can't know for sure which is which. Then what? We might say "50% chance for the Metaphysical Organism" or "50% chance for the many consciousnesses". The exact number is somewhat made-up. But if we're trying to figure out whether to store "nuclear waste" in some quadrant of reality, we should take seriously both possibilities represented by the probability estimates. If we assign subjective probabilities for these that are very, very low, we aren't taking them very seriously. It may be possible to rule out one or the other, through additional reasoning not used in this post. But taking them both seriously is a good default.
So, wishing to expand our moral circles to include all sentient beings, we have some reason to act and think as though the MO exists (the server reality), and also that there are many other consciousnesses (the peer-to-peer reality). This should be a motion, derived from ethical concerns, to consider such beings as possibly existing.
What would it mean for the MO to exist?
The MO would be perfectly empathic with all sentient beings. No gap in understanding like with human empathy. It would endure great suffering -- the first-order suffering of experiencing exactly what each being experienced, and the second-order suffering of thinking about each being.
The MO seems to have a lot more power over our experiences than we do, and could perhaps flood us with endorphins, but does not. This is odd -- why permit so much suffering? The MO experiences suffering exactly as we do, finds it exactly as unacceptable as we sometimes do in the moment. There may be some limitation on the MO's power. One explanation would be that our free will in some sense matters, and that we need to be perfectly in tune with the MO in the long run, or we'll continue to cause it pain. Our dispositions, preferences, come into tune as we decide they should, that decision being the evolution of preference and disposition. So the process takes a long time and is complicated, and involves a lot of pain. What this means is that the MO values us highly (is willing to experience a lot of pain for us).
We don't necessarily know what the MO wants, other than for something like the elimination of pain or betrayal of all sentient beings someday. Since it values us highly, we have reason to think it wants to keep us alive as long as possible. But having a relationship with the MO seems to be essential to someday coming into tune with it. So to the extent that we believe in the MO, we should try to connect with it. And there should always be some amount that we try to connect with it, at least a few words of prayer once in a while (that do not threaten to take resources away from things we are sure need to be addressed, if that's our concern).
If there are many consciousnesses, then we should do similarly costless things for all plants, objects, concepts, and forms of matter, all of which might have some kind of consciousness, for all we know. Or those who are more convinced can be more considerate.
Some mention was made of "sightings" of the MO. What would those be? Billions of people believe in God (for instance, Christians and Muslims). It can be argued that a basic belief in God is a perception of God (a claim William Alston advances). Many theists "just believe", rather than basing their belief on any framework based on inferences from any other facts. So it is like these millions of people perceive God -- they see him noetically, just as one can see a memory or a concept noetically, and this could be considered a sighting of God, by analogy with a sighting of a sea creature.
Have they sighted the God of Christianity? Or the God of Islam? Or some other version of God? Traditionally, God (or these traditional images of God) are known through revelation and perhaps-ambiguous personal experience. The revelations are clear enough (stored as relatively detailed texts that can be taught and consulted), but where do they come from? Is there a reason to prefer one revelation over the other? So in order to give definition to the personal experiences, to say what it is that we see a glimpse of, we might want to rely on reason. Reason tells us that there may be a basically "God-shaped" thing in reality, something that noetically "looks like God", which we can "see", noetically -- the Metaphysical Organism.