1. What is Computation? it is the manipulation of arbitrarily shaped formal symbols in accordance with symbol-manipulation rules, algorithms, that operate only on the (arbitrary) shape of the symbols, not their meaning.
2. Interpretatabililty. The only computations of interest, though, are the ones that can be given a coherent interpretation.
3. Hardware-Independence. The hardware that executes the computation is irrelevant. The symbol manipulations have to be executed physically, so there does have to be hardware that executes it, but the physics of the hardware is irrelevant to the interpretability of the software it is executing. It’s just symbol-manipulations. It could have been done with pencil and paper.
4. What is the Weak Church/Turing Thesis? That what mathematicians are doing is computation: formal symbol manipulation, executable by a Turing machine – finite-state hardware that can read, write, advance tape, change state or halt.
5. What is Simulation? It is computation that is interpretable as modelling properties of the real world: size, shape, movement, temperature, dynamics, etc. But it’s still only computation: coherently interpretable manipulation of symbols
6. What is the Strong Church/Turing Thesis? That computation can simulate (i.e., model) just about anything in the world to as close an approximation as desired (if you can find the right algorithm). It is possible to simulate a real rocket as well as the physical environment of a real rocket. If the simulation is a close enough approximation to the properties of a real rocket and its environment, it can be manipulated computationally to design and test new, improved rocket designs. If the improved design works in the simulation, then it can be used as the blueprint for designing a real rocket that applies the new design in the real world, with real material, and it works.
7. What is Reality? It is the real world of objects we can see and measure.
8. What is Virtual Reality (VR)? Devices that can stimulate (fool) the human senses by transmitting the output of simulations of real objects to virtual-reality gloves and goggles. For example, VR can transmit the output of the simulation of an ice cube, melting, to gloves and goggles that make you feel you are seeing and feeling an ice cube. melting. But there is no ice-cube and no melting; just symbol manipulations interpretable as an ice-cube, melting.
9. What is Certainly Truee (rather than just highly probably true on all available evidence)? only what is provably true in formal mathematics. Provable means necessarily true, on pain of contradiction with formal premises (axioms). Everything else that is true is not provably true (hence not necessarily true), just probably true.
10.  What is illusion? Whatever fools the senses. There is no way to be certain that what our senses and measuring instruments tell us is true (because it cannot be proved formally to be necessarily true, on pain of contradiction). But almost-certain on all the evidence is good enough, for both ordinary life and science.
11. Being a Figment? To understand the difference between a sensory illusion and reality is perhaps the most basic insight that anyone can have: the difference between what I see and what is really there. “What I am seeing could be a figment of my imagination.” But to imagine that what is really there could be a computer simulation of which I myself am a part  (i.e., symbols manipulated by computer hardware, symbols that are interpretable as the reality I am seeing, as if I were in a VR) is to imagine that the figment could be the reality – which is simply incoherent, circular, self-referential nonsense.
12.  Hermeneutics. Those who think this way have become lost in the “hermeneutic hall of mirrors,” mistaking symbols that are interpretable (by their real minds and real senses) as reflections of themselves — as being their real selves; mistaking the simulated ice-cube, for a “real” ice-cube.

Slime molds are certainly interesting, both as the origin of multicellular life and the origin of cellular communication and learning. (When I lived at the Oppenheims’ on Princeton Avenue in the 1970’s they often invited John Tyler Bonner to their luncheons, but I don’t remember any substantive discussion of his work during those luncheons.)

The NOVA video was interesting, despite the OOH-AAH style of presentation (and especially the narrators’ prosody and intonation, which to me was really irritating and intrusive), but the content was interesting – once it was de-weaseled from its empty buzzwords, like “intelligence,” which means nothing (really nothing) other than the capacity (which is shared by biological organisms and artificial devices as well as running computational algorithms) to learn.

The trouble with weasel-words like “intelligence,” is that they are vessels inviting the projection of a sentient “mind” where there isn’t, or need not be, a mind. The capacity to learn is a necessary but certainly not a sufficient condition for sentience, which is the capacity to feel (which is what it means to have a “mind”). 

Sensing and responding are not sentience either; they are just mechanical or biomechanical causality: Transduction is just converting one form of energy into another. Both nonliving (mostly human synthesized) devices and living organisms can learn. Learning (usually) requires sensors, transducers, and effectors; it can also be simulated computationally (i.e., symbolically, algorithmically). But “sensors,” whether synthetic or biological, do not require or imply sentience (the capacity to feel). They only require the capacity to detect and do.

And what sensors and effectors can (among other things) do, is to learn, which is to change in what they do, and can do. “Doing” is already a bit weaselly, implying some kind of “agency” or agenthood, which again invites projecting a “mind” onto it (“doing it because you feel like doing it”). But having a mind (another weasel-word, really) and having (or rather being able to be in) “mental states” really just means being able to feel (to have felt states, sentience).

And being able to learn, as slime molds can, definitely does not require or entail being able to feel. It doesn’t even require being a biological organism. Learning can (or will eventually be shown to be able to) be done by artificial devices, and to be simulable computationally, by algorithms. Doing can be simulated purely computationally (symbolically, algorithmically) but feeling cannot be, or, otherwise put, simulated feeling is not really feeling any more than simulated moving or simulated wetness is really moving or wet (even if it’s piped into a Virtual Reality device to fool our senses). It’s just code that is interpretable as feeling, or moving or wet. 

But I digress. The point is that learning capacity, artificial or biological, does not require or entail feeling capacity. And what is at issue in the question of whether an organism is sentient is not (just) whether it can learn, but whether it can feel. 

Slime mold — amoebas that can transition between two states, single cells and multicellular  — is extremely interesting and informative about the evolutionary transition to multicellular organisms, cellular communication, and learning capacity. But there is no basis for concluding, from what they can do, that slime molds can feel, no matter how easy it is to interpret the learning as mind-like (“smart”). They, and their synthetic counterparts, have (or are) an organ for growing, moving, and learning, but not for feeling. The function of feeling is hard enough to explain in sentient organisms with brains, from worms and insects upward, but it becomes arbitrary when we project feeling onto every system that can learn, including root tips and amoebas (or amoeba aggregations).

I try not to eat any organism that we (think we) know can feel — but not any organism (or device) that can learn.

They can also produce sounds when they are swayed by the wind, and when their fruit drops to the ground.

They can also produce sights when their leaves unfurl, and when they flower.

And they can produce scents too.

And, yes, animals can detect those sounds and sights and scents, and can use them, for their own advantage (if they eat the plant), or for mutual advantage (e.g., if they are pollinators).

Plants can also produce chemical signals, for signalling within the plant, as well as for signalling between plants.

Animals (including humans) can produce internal signals, from one part of their immune system to another, or from a part of their brain to another part, or to their muscles or their immune system.

Seismic shifts (earth tremors) can be detected by animals, and by machines.

Pheromones can be produced by human secretions and detected and reacted to (but not smelled) by other humans.

The universe is full “signals,” most of them neither detected nor produced by living organisms, plant or animal.

Both living organisms and nonliving machines can “detect” and react to signals, both internal and external signals; but only sentient organisms can feel them. 

To feel signals, it is not enough to be alive and to detect and react to them; an organ of feeling is needed: a nervous system.

Nor are most of the signals produced by living organisms intentional; for a signal to be intentional, the producer has to be able to feel that it is producing it; that too requires an organ of feeling.

Stress is an internal state that signals damage in a living organism; but in an insentient organism, stress is not a felt state.

Butterflies have an organ of feeling; they are sentient. 

Some species of butterfly have evolved a coloration that mimics the coloration of another, poisonous species, a signal that deters predators who have learned that it is often poisonous. 

The predators feel that signal; the butterflies that produce it do not.

Evolution does not feel either; it is just an insentient mechanism by which genes that code for traits that help an organism to survive and reproduce get passed on to its progeny.

Butterflies, though sentient, do not signal their deterrent color to their predators intentionally.

Nor do plants that signal by sound, sight or scent, to themselves or others, do so intentionally.

All living organisms except plants must eat other living organisms to survive. The only exceptions are plants, who can photosynthesize with just light, CO2 and minerals.

But not all living organisms are sentient.

There is no evidence that plants are sentient, even though they are alive, and produce, detect, and react to signals. 

They lack an organ of feeling, a nervous system.

Vegans need to eat to live.

But they do not need to eat organisms that feel.

Khait, I., Lewin-Epstein, O., Sharon, R., Saban, K., Perelman, R., Boonman, A., … & Hadany, L. (2019). Plants emit informative airborne sounds under stress. bioRxiv 507590.

Wilkinson, S., & Davies, W. J. (2002). ABA‐based chemical signalling: the co‐ordination of responses to stress in plants. Plant, cell & environment, 25(2), 195-210.

SIGNAUX ET SENTIENCE

Oui, les plantes peuvent produire des sons lorsqu’elles sont stressées par la chaleur, la sécheresse ou les dommages.

Elles peuvent également produire des sons lorsqu’elles sont agitées par le vent et lorsque leurs fruits tombent au sol.

Elles peuvent également produire des vues lorsque leurs feuilles se déploient et lorsqu’elles fleurissent.

Et elles peuvent aussi produire des parfums.

Et, oui, les animaux peuvent détecter ces sons, ces vues, et ces odeurs, et ils peuvent les utiliser, pour leur propre avantage (s’ils mangent la plante) ou pour un avantage mutuel (s’ils sont des pollinisateurs).

Les plantes peuvent également produire des signaux chimiques, pour la signalisation à l’intérieur de la plante, ainsi que pour la signalisation entre les plantes.

Les animaux (y compris les humains) peuvent produire des signaux internes, d’une partie de leur système immunitaire à une autre, ou d’une partie de leur cerveau à une autre partie, ou à leurs muscles ou à leur système immunitaire.

Les déplacements sismiques (tremblements de terre) peuvent être détectés par les animaux ainsi que par les machines.

Les phéromones peuvent être produites par les sécrétions humaines et elles peuvent être détectées et réagies (mais non sentis) par d’autres humains.

L’univers est plein de « signaux », dont la plupart ne sont ni détectés ni produits par des organismes vivants, végétaux ou animaux.

Les organismes vivants et les machines non vivantes peuvent « détecter » et réagir aux signaux, qu’ils soient internes ou externes ; mais seuls les organismes sentients peuvent les ressentir.

Pour ressentir des signaux, il ne suffit pas d’être vivant, de les détecter et d’y réagir ; il faut un organe du ressenti : un système nerveux.

La plupart des signaux produits par les organismes vivants ne sont pas non plus intentionnels ; pour qu’un signal soit intentionnel, il faut que le producteur puisse ressentir qu’il le produit ; cela aussi exige un organe du ressenti.

Le stress est un état interne qui signale des dommages dans un organisme vivant ; mais dans un organisme non sentient, le stress n’est pas un état ressenti.

Les papillons ont un organe du ressenti ; ils sont sentient.

Certaines espèces de papillons ont évolué une coloration qui imite la coloration d’une autre espèce vénéneuse, un signal qui dissuade les prédateurs qui ont appris que c’est souvent toxique.

Les prédateurs ressentent ce signal; les papillons qui le produisent ne le ressentent pas.

L’évolution darwinienne ne ressent pas non plus ; c’est juste un mécanisme non sentient par lequel les gènes qui encodent les traits qui aident un organisme à survivre et à se reproduire sont transmis à sa progéniture.

Les papillons, bien que sentients, ne signalent pas intentionnellement leur couleur dissuasive à leurs prédateurs.

Les plantes qui signalent par le son, la vue ou l’odeur, à elles-mêmes ou aux autres, ne le font pas non plus intentionnellement.

Tous les organismes vivants, à l’exception des plantes, doivent manger d’autres organismes vivants pour survivre. Les seules exceptions sont les plantes, qui peuvent effectuer la photosynthèse avec juste de la lumière, du CO2 et des minéraux.

Mais tous les organismes vivants ne sont pas sentients.

Il n’y a pas de preuve que les plantes soient sentientes, même si elles sont vivantes, et produisent, détectent et réagissent aux signaux.

Il leur manque un organe de ressenti, un système nerveux.

Les véganes nécessitent manger pour survivre.

Mais ils ne nécessitent pas manger les organismes qui ressentent.

Khait, I., Lewin-Epstein, O., Sharon, R., Saban, K., Perelman, R., Boonman, A., … & Hadany, L. (2019). Plants emit informative airborne sounds under stress. bioRxiv 507590.

Wilkinson, S., & Davies, W. J. (2002). ABA‐based chemical signalling: the co‐ordination of responses to stress in plants. Plant, cell & environment, 25(2), 195-210.

Biological organisms are living beings. Some (not all) living beings (probably not plants, nor microbes, nor animals with no nervous system) are also sentient beings. That means they are not just alive, surviving and reproducing; they also feel.

And with feeling comes the capacity to be hurt. Chairs & tables, glaciers & shorelines, and (probably) plants & microbes can be damaged, but they cannot be hurt. Only sentient beings can be hurt because it feels like something to be hurt.

Most organisms are heterotrophic, meaning that they have to consume other organisms in order to survive. (The exceptions are autotrophs like green plants, algae and photosynthetic bacteria.)

This means that nature is full of conflicts of vital (life-or-death) interests: predator vs. prey. If the prey is sentient (i.e., not a plant), this means that the predator has to harm the prey in order to survive (by killing and eating it) — and the prey has to harm the predator to survive (by fighting back or escaping, depriving the predator of food).

It also has to be pointed out that there is no point trying to make conflicts of vital interest into a moral issue. They are a biological reality — a matter of biological necessity, a biological imperative — for heterotrophic organisms. And there is no right or wrong or choice about it: The survival of one means the non-survival of the other, as a matter of necessity.

But now comes the unique case of the human species, which is sentient and also, like all heterotrophic species, a predator. Its prey are plants (almost certainly insentient)  and animals (almost certainly sentient). But unlike obligate carnivores (like the felids), humans also have a choice. They can survive, in full health, as either carnivores or herbivores, or both. We are facultative omnivores.

The primates probably evolved from earlier herbivore/insectivore species, but there is no doubt that most primates, including the great apes, are also able to eat small mammals, and sometimes do. Our own species’ evolutionary history diverged from this mostly herbivore origin; we became systematic meat hunters; and there is no doubt that that conferred an adaptive advantage on our species, not just in getting food but also in evolving some of the cognitive traits and the large brain that are unique to our species.

Far fewer of our ancestors would have survived if we had not adapted to hunting. They did it out of necessity; a biological imperative — just as it was under pressure of a biological imperative that our ancestors, especially children, evolved a “sweet tooth,” a predilection for sugar, which was rare, and it was important to consume as much as we could when we could get it, because we had many predators and needed the energy to escape. By the same token, our predilection for aggression and violence, toward other species as well as our own, had been adaptive in our ancestral environment.

But in our current environment many of these ancestral predilections are no longer necessary, and indeed some of them have become (mildly) maladaptive : Our predilection for sugar, now abundant (whereas predators are almost nonexistent), when unchecked, has become an important cause of dental cavities, hyperactivity, obesity and diabetes (but not maladaptive enough to kill or prevent enough of us from reproducing to eliminate their genes from our gene pool). Our predilection for aggression and violence, when unchecked, is leading to ever more deadly forms of warfare and devastation (but not deadly enough, yet).

And in the same way, our unchecked taste for animal protein has led to industrial production of livestock, water depletion, air pollution, climate change, antibiotic overuse (creating superbugs), and a large variety of human ailments (on which others are more expert than I). But the point is that we have retained our hominid capacity to survive, in full health, without animal protein. We are, and always have been, facultative omnivores — with two metabolic modes herbivore and omnivore — that could adapt to different environments. 

So far, I’ve only mentioned the negative consequences of animal protein consumption for us along with the positive consequences of  not consuming animal protein, for us.
But let me not minimize the moral/bioethical aspect. Even if, setting aside the climatic aspects, the direct health benefits of our no longer eating meat are, for us, only mild to moderate, the harm and hurt of our continuing to eat meat are, for our sentient victims, monstrous.

And it should not be left unsaid that the clinical hallmark of a psychopath is the fact that if they want to get something, psychopaths are unmoved if getting it hurts others, even when what they want to get is not a vital necessity. That is why it is so important that people are fully informed of the fact that meat eating is not necessary for human health and causes untold suffering to other sentient beings. Because most people are not, and do not want to be, psychopaths.

If these were paired genetic alleles, we’d have to admit that the selfish ones have the edge.

But bullying and rule-breaking is also, by its nature, a minority strategy, because to open an unfair advantage a baseline of fairness has to be the norm.

So cheating must keep waxing and waning — an unstable, unsustainable strategy, whether genetically or socially — because if everyone lies, cheats, steals, bullies, the strategy has no victims left: Its advantage is over innocent victims. So a critical mass of those has to be sustained, otherwise cheating implodes…

…unless there is a way to enslave the victims, as humans have done to nonhuman animals.

Un vide minuscule, énorme, irremplissable.

Persistons, pour toutes les d.

But the difference between whether an organism has or lacks the capacity to feel anything at all , be it ever so faint or brief, is all-or-none, not a matter of degree along some sort of “continuum.”

Mammals, birds, reptiles, fish, and probably most or all invertebrates can feel (something, sometimes) — but not rhododendrons or Rhizobium radiobacter or Rutstroemia firma… or any of today’s robots.

There is no more absolute difference than that between a sentient entity and an insentient one, even if both are living organisms.

(Sedatives can dim feeling, general anesthesia can temporarily turn it off, and death or brain-death can turn it off permanently, but the capacity or incapacity to feel anything at all, ever, is all-or-none.)

“I have taken some time to reflect because I think the situation is too serious to comment on without really giving it thought.

Yes, приятелька. no call for snap judgments when unprovoked bombs are again raining on Ukraine from a nuclear superpower, thrice its size, and people are dying. Just stress that you are a patriot, and apolitical.

“First of all: I am opposed to this war…

And that is of course what you say to твоему приятельнику, Володке, each time you meet…

 “I am Russian and I love my country… 

Very reassuring, and very à propos – when your country is bombing Ukraine…

“…but I have many friends in Ukraine and the pain and suffering right now breaks my heart.

To hear what you are going through breaks my heart…

“ I want this war to end and for people to be able to live in peace. This is what I hope and pray for. 

And what I wanted when I presented 1M rubles to the Russian nationalist leader, draped in the Russian secessionist flag, when my country invaded and annexed Crimea… 

“I want to add one thing, however: forcing artists, or any public figure, to voice their political opinions in public and to denounce their homeland is not right. This should be a free choice. Like many of my colleagues, I am not a political person. I am not an expert in politics. I am an artist and my purpose is to unite people across political divides.’

Which was also what I had in mind when I presented 1M rubles to the Russian nationalist leader, draped in the Russian secessionist flag, when my country invaded and annexed Crimea…

To hear what you are having to go through to save your career breaks the whole world’s heart…

Dale Jamieson’s heart is clearly in the right place, both about protecting sentient organisms and about protecting their insentient environment.

Philosophers call deserving such protection “meriting moral consideration” (by humans, of course).

Dale points out that humans have followed a long circuitous path — from thinking that only humans, with language and intelligence, merit moral consideration, to thinking that all organisms that are sentient (hence can suffer) merit moral consideration.

But he thinks sentience is not a good enough criterion. “Agency” is required too. What is agency? It is being able to do something deliberately, and not just because you were pushed.

But what does it mean to be able to do something deliberately? I think it’s being able to do something because you feel like it rather than because you were pushed (or at least because you feel like you’re doing it because you feel like it). In other words, I think a necessary condition for agency is sentience. 

Thermostats and robots and microbes and plants can be interpreted by humans as “agents,” but whether humans are right in their interpretations depends on facts – facts that, because of the “other-minds problem,” humans can never know for sure: the only one who can know for sure whether a thing feels is the thing itself. 

(Would an insentient entity, one that was only capable of certain autonomous actions — such as running away or defending itself if attacked, but never feeling a thing – merit moral consideration? To me, with the animal kill counter registering grotesque and ever grandescent numbers of human-inflicted horrors on undeniably sentient nonhuman victims every second of every day, worldwide, it is nothing short of grotesque to be theorizing about “insentient agency.”)

Certainty about sentience is not necessary, however. We can’t have certainty about sentience even for our fellow human beings. High probability on all available evidence is good enough. But then the evidence for agency depends on the evidence for sentience. It is not an independent criterion for moral consideration; just further evidence for sentience. Evidence of independent “choice” or “decision-making” or “autonomomy” may count as evidence for “agency,” but without evidence for sentience we are back to thermostats, robots, microbes and plants.

In mind-reading others, human and nonhuman, we do have a little help from Darwinian evolution and from “mirror neurons” in the brain that are active both when we do something and when another organism, human or nonhuman, does the same thing. These are useful for interacting with our predators (and, if we are carnivores, our prey), as well as with our young, kin, and kind (if we are K-selected, altricial species who must care for our young, or social species who must maintain family and tribal relationships lifelong). 

So we need both sentience-detectors and agency-detectors for survival. 

But only sentience is needed for moral consideration.

1. Computation is not a subset of AI. 

2. AI (whether “symbolic” AI or “connectionist’ AI) is an application of computation to cogsci.

3. Computation is the manipulation of symbols based on formal rules (algorithms).

4. Symbols are objects or states whose physical “shape” is arbitrary in relation to what they can be used and interpreted as referring to.

5. An algorithm (executable physically as a Turing Machine) manipulates symbols based on their (arbitrary) shapes, not their interpretations (if any).

6. The algorithms of interest in computation are those that have at least one meaningful interpretation.

7. Examples of symbol shapes are numbers (1, 2, 3), words (one, two, three; onyx, tool, threnody), or any object or state that is used as a symbol by a Turing Machine that is executing an algorithm (symbol-manipulation rules).

8. Neither a sensorimotor feature of an object in the world, nor a sensorimotor feature-detector of a robot interacting with the world, is a symbol (except in the trivial sense that any arbitrary shape can be used as a symbol).

9. What sensorimotor features (which, unlike symbols, are not arbitrary in shape) and sensorimotor feature-detectors (whether “symbolic” or “connectionist”) might be good for is connecting symbols inside symbol systems (e.g., robots) to the outside objects that they can be interpreted as referring to.

10. If you are interpreting “symbol” in a wider sense than this formal, literal one, then you are closer to lit-crit than to cogsci.