Assuming that there are different "beings" in this world, and that those beings have something like "emotions" (those are two big pills to swallow, I know), how do you tell whether a particular being is feeling something "good" or "bad"?

For example, we've figured out the facial expressions that mice usually use in response to particular stimuli. But how do we know if those facial expressions are those of "pain" or "pleasure"?

In the case of mice, we're pretty sure they're similar to humans because their brain structure is very similar to humans, and brains seem to have a large impact on emotions, and we know how we feel.

If there's a creature with a different brain structure from humans, how could we go about figuring out what they feel?

Edit: While this does have relations to the "Hard Problem of Consciousness" If I understand the "Hard problem" correctly, it's understanding why and how beings feel things. It's not trying to answer what those feelings are. (That is it's not trying to determine whether the feeling feels "good" or "bad".) Solving the "Hard problem" will hopefully allow us to answer this question, but the two are not the same.

Further clarification: For example, for humans where we assume that we understand them correctly, we may want to predict how the human will respond to the question "How are you feeling?" or "What emotion are you experiencing?" My question is if there are general methods of making this sort of prediction for creatures with different brain structures than humans. That is, I assume that other creatures have feelings. (I'm not explicitly wondering why or how they have feelings, which I believe is the goal of the hard problem of consciousness.) But what are those feelings like?

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    You would "tell whether a particular being is feeling something 'good' or 'bad'," by using empiricism. if you decide that chocolate is good, on your own, and someone else who tries chocolate tells you that chocolate is good, you can have certainty that 2 people agree that chocolate is good... now say you ask a 100 people, and 98% say chocolate is good. you can decide/measure on your own that chocolate is good. We empirically measure others experiences
    – Noah
    Apr 5, 2020 at 3:53
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    We do not even "know" how pain or pleasure of other humans "feels like". And if you think about it you'll see that the idea of such "knowing" is incoherent, as we would have to become something other than ourselves to "feel" it.
    – Conifold
    Apr 5, 2020 at 8:15
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    What is it like to be Thomas Nagel?
    – Joseph Weissman
    Apr 5, 2020 at 14:10
  • Since the question has been edited, the OP's notion of a feeling seems to have changed; a lot of the initial comments and answers no longer address it. The Hard Problem and qualities of inner experience are no longer relevant. Should I trim my answer accordingly? Apr 6, 2020 at 12:33
  • Empiricism seems to take a strong stance not only on other minds (they exist) and other's feelings (they exist) and is supported at least by the abject failure of behaviorism. In fact, the neurological mechanisms for psychological altruism and empathy are under active scientific investitation and include terms like mirror neuron. I guess if you reject science, evolution, and cognitive science, this solipsist line of thinking holds some merit.
    – J D
    Apr 7, 2020 at 3:50

3 Answers 3


The octopus is probably quite a good model. It is included among the sentient creatures in the Cambridge Declaration on Consciousness, which states that;

“The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”

So if a creature has the necessary brain features and exhibits intentional behaviours, then we know that it is feeling something.

But what? This we can never know in any absolute sense. We can never even know what other people are experiencing subjectively - is my red the same as your red? We might assume so until we discover that the human eye has two different pigments which respond to different wavelengths in its red cells, some of us have one, or the other, or both, and there are gender differences. Thus, two of us looking at the same scene will have physically different shades of yellow and purple encoded along their optic path. But do we experience those shades differently or does our consciousness adjust so that we experience the same quality - the exact same quale ("kwa-ley") of yellow? Then of course, to somebody who has been blind from birth, the whole thing is an impenetrable mystery.

So there are two aspects to the "feelings" that you ask about, the objective neurological signal and the subjective conscious experience of that signal. The one is tractable, the other is not.

At this point philosophers label it part of the "hard problem" in the theory of mind and most give up. But I think there is a lesson for us from the rejection of solipsism. Our experiences are sufficiently structured and repeatable, yet uncontrollable in many ways, that we reject the idea that our stream of consciousness is all there really is. Whatever our theoretical quibbles might be, in practice we accept the existence of other people, their thoughts and subjective experiences. On the same basis, why not accept the consistency of qualia (plural of quale) across all individuals? OK we cannot know how or why qualia arise but it is a fair guess that they are as consistent across individuals as our brains may allow.

Back to the octopus. Our last common ancestor with it was a flatworm with a central nerve cord and a couple of light-sensitive eye spots. Our brains evolved wholly separately from then on and our physiologies are very different. The octopus ended up with nine brains, one for each arm and one wrapped round its gut. The central brain has structures which closely resemble our own cortex in being rather like the ratlines of an old windjammer; longitudinal cords along which signals travel as they are progressively processed, with many side branches cross-linking the main cords. We interpret this as an example of convergent evolution, in which the same need for highly complex thought processes has driven the evolution of similar morphologies.

But what colours does an octopus experience? How might it feel fear, aggression or comradeship? We have absolutely no way of knowing. Even if we developed better mind-reading machines and put on the receiving cap, we would only confirm the specific experiences were present; no objective lab device can capture the subjective feel of those experiences. Then again, the octopus has electric senses similar to sharks and so on, and we are as ignorant of those qualia as the blind main is of yellow. How would the mind-reading machine represent those experiences to our brains?

Thus, in comparing the octopus with ourselves, the argument from solipsism stretches very thin and cannot be sustained. All we can really suggest is that the more similar two octopus species are neurologically, the more similar their qualia will be to each other's.

So although we can use behavioural and neurological methods to gain a pretty good idea of what emotions another creature is experiencing, once they begin to depart significantly from our own neurology, we can never have the slightest idea what their conscious, subjective experience of those emotions feels like.

In the case of mice, their brains are at least mammalian, so it is tempting to apply the inductive rejection of solipsism to their feelings, however residual those might be. But as the first couple of comments to the question show, this is not a common judgement.

  • Doesn't giving up like this tacitly amount to solipsism? Don't behavioural & neurological methods' generate insights, and further methods more, on a track towards knowledge about it's subjectivity & affective states? The fact octopuses dream youtu.be/0vKCLJZbytU indicates convergence also.
    – CriglCragl
    Apr 6, 2020 at 8:43
  • Solipsism denies the reality of others' subjective experience, confession of ignorance is not denial. As a parallel example, consider the mind of God; agnosticism is not atheism. For the rest, you blur the meaning of "subjectivity". Apr 6, 2020 at 9:20
  • If it's unknowable even in principle, is it meaningfully real?
    – CriglCragl
    Apr 6, 2020 at 9:21
  • "If it's unknowable even in principle, is it meaningfully real?" To a scientific positivist, no, everbody else is a dumb machine and solipsism is the only tenable outcome. To most of us, yes, other people's inner experiences are as real as our own. It's not called the "hard problem" for nothing. Apr 6, 2020 at 9:40
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    My concern is that it is not meaningful even in the usual metaphysical context, where we, roughly, pretend to look at things through the God's eye. That works for solipsism. But not even God can experience somebody else's experiencing any more than he can create a stone that he can not lift, both conceptions are logically incoherent. The "looking through somebody else's eye" is a tempting metaphor that breaks down completely when applied to qualia. It becomes a linguistic trap of a properly constructed sentence that is devoid of any meaning.
    – Conifold
    Apr 6, 2020 at 20:23

I see the Private Language argument as the best way to dismiss solipsism, and to establish that truly private experiences are not coherent - though considering non-social adaptively intelligent animals seems to indicate limits to that (in the sense of language as conceptual abstracts, but not in the sense of a shared cognitive/evolutionary space of mutual relatable subjective experience, arguably the substrate of language)

Through being raised as children and enculturated, we establish shared meanings founded in shared modes of life. These are what are important, rather than the private subjective experience. We know a colourblind person sees colours differently, but in most situations they are able use colours in socially appropriate ways. Typical colourblindness (deuteranomaly or red-green type) people only have two types of cone cell active. There are also thought to be some people, women in families prone to that condition, with four active cone cell types, adding additional sensitivity at the red end of the spectrum - it is notable that does not seem to have been picked up socially in an obvious way. Feelings, like colours, are not important primarily for their private qualities, though they initiate instinctive responses like fear-alertness, but are shaped and directed and deepened by being enmeshed in shared modes of life, and collectively socially meaningful only through shared context, whether intuitions we have about bodies like our own or language.

There are 'culturally local' experiences, achieved through their practices, like initiation rights, festivals with a certain state of mind or attitude cultivated, or language structures and associated bodies of stories and literature that exemplify it's scope. There are fundamental limits how far we can truly translate these, it takes somebody with deep experience of not only two languages but two cultures, and even then a description is bound to leave gaps - I am thinking of something like the film The Colour Of Pomegranites https://youtu.be/26tEfblGH5I about lost Armenian culture, which is an amazing work but can only point enigmatically towards fragments.

The Rosetta Stone is a landmark in language translation, opening up the 'dead' scripts of demotic and hieroglyphic Ancient Egyptian. The decipherment of Linear B script for Ancient Greek is another landmark https://en.m.wikipedia.org/wiki/Linear_B#Discovery_and_decipherment We can't know how much is lost in translation, but tomb inscription, tablets recording debts, and political declarations certainly expand our cultural insights.

What is necessary for 'good translations' gives a key insight into possibilities for interspecies communication, I would contend. We can't just map words & concepts, there needs to be enough meshing of modes of life to learn one culture in context, and experience another - typically this is hugely aided by exposure to both languages and cultures in childhood, especially if they are very different. We also need cultural continuity, like between Ancient China and modern China where intermediate texts let us understand objects and concerns in context. The example is maybe clearer in English, where Shakespeare invented at least 15 words many now very commonly used, and many more turns of phrase which might be obscured to a new speaker of the language without access to his work.

Dolphins have been shown to have a very different mode of communication to humans https://upliftconnect.com/dolphins-communicate-holographically This opens up a great deal more scope for interaction, and sharing of modes of life. There are already humans spending substantial amounts of time with wild dolphins, teaching games and use of toys towards building communication. This cymatic method could likely result in a tool for real-time decryption of dolphin communication, and we might expect a cumbersome sending of preset patterns using some kind of computer, or a more sophisticated flexible sending using a direct-brain input like proposed by Neuralink.

That would enable basic exchange of information. Our genes mean we have a lot in common with dolphins emotionally, as fellow mammals, so a lot of extra implicit information could come with body-language and demeanor correlated with signals (we have a substantial grounding in a shared mode of life, similar bodies - cephalopods that be harder, though we think there has been convergence). We might try children with these tools, or by then be able to induce language neuroplasticity in adults. But to really get deeper insights, humans would have to live more fully with dolphins, live like dolphins. Equivalent to gaining cultural continuity. It seems there needs to be a grounding of shared mapping to reality, constituted of theory-of-mind and modes of life including meaning structures. Context in that is what will reveal the nature of another species' emotions, and even then the fidelity will relate to how deeply we can become meshed with that mapping.

Statistical arguments, how early life occurred on Earth, and the development of multicellular life on at least six different occasions suggest complex life is common in the universe, and communicating with aliens will be the truly grand challenge. It might have to involve creating hybrid beings capable of experiencing the modes of life and cultures of both species. It might be that a substantial development track by humans/Earth life would be needed to interact with aliens capable of interstellar travel. Or, there may have been convergence towards similar behaviours and mental structures that allow communication more readily.

  • I think that languages are great for predicting behavior in social settings, but I'm worried about a case that's described in the sequel to Ender's Game by Orson Scott Card, "Speaker for the Dead", where the two groups, humans and another alien species are able to socially understand what's going to happen for a long time, but fail to predict how those actions make each other feel. For one culture, a ritual is merely a metamorphosis, like a butterfly. For the other culture, the ritual is extremely painful and kills them.
    – Pro Q
    Apr 5, 2020 at 22:16
  • If we're able to show that there's always a link between emotion and behavior, then I think you may be right. But I think that's a key link that needs to be expressed. We may also end up with a conclusion along the lines of "the only emotions that matter are those that are linked with behavior". But I think we then need to be careful because we can have emotions that are not tied to behavior, or at least, so disconnected that it's very difficult to find the link.
    – Pro Q
    Apr 5, 2020 at 22:19
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    @ProQ: Yeah I struggled to not mention scifi. The Strugatsky brother's Roadside Picnic is my favourite illustration of how big the gulf may be. 2001 too. On emotion you have to look at it's functional role, in tagging memories for context, & activating appropriate states of arousal. These functional qualities are the point, not ineffable private internal qualia, that was my argument. Behaviour includes biology; if it's not affecting the body or behaviour, discount it. Yes sure impacts might be subtle, hence the need to mesh mappings & enter fully the alternate modes of life
    – CriglCragl
    Apr 6, 2020 at 8:37
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    @ProQ: This is at the very initial stage, but my understanding is this posited as being not only what dolphins can receive, but also what they send. Yes this is a jump, but one which hopefully can be tested in the near future
    – CriglCragl
    Apr 10, 2020 at 23:23
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    You are correct; I failed to read the last sentence of the report - thank you for the clarification.
    – Pro Q
    Apr 12, 2020 at 3:40

It is not possible to tell something objective about the "feelings" of a non-human entity due to multiple reasons.

First, the concept of feeling is the result of a set of subjective experiences. Even if you agree about the meaning of pain with another human being, the concepts behind are completely different. Each one develops an idea of what it does mean and uses a set of symbols in order to communicate it to other humans (see Locke). Even if each one lives a radically particular life, we are able to agree about multiple concepts on the surface. But that cannot be agreed with other type of entities, as works, roses, viruses or rocks.

Second, any feeling is dependent on consciousness. Without consciousness, no feelings can exist, just a mechanical causal reaction, which is the same in an animal or a video-game character which is apparently suffering. But there are different positions in this regard. See https://plato.stanford.edu/entries/moral-animal/

Third, the attempt to assimilate human features to non-human entities is called humanization. Animals or puppets are no humans, and it is useless to humanize them. Of course, vegetarians do not agree with this argument.

how do you tell whether a particular being is feeling something "good" or "bad"?

Disclaimer: this is from my book regarding physical interaction: interacting entities follow an essential behavior related to its persistence in time (survival, for living beings): attraction and rejection. When a subject profits of an interaction with an object, it will express it as attraction, which is aimed to repeat it. In the opposite case, the subject repeals the object in order to avoid repetition. That is quite clear: give a dog a bone, and it'll be attracted to you and will try to repeat the interaction. Cause it pain, and it will try to be away from you. Important note: all entities have a subjective reaction, which is aimed only to survive. For example, give cocaine to a young, and he'll try to repeat the interaction, although it will kill him on the long term. It was only trying to survive, but it followed a wrong instinct. That's how living beings get extinct and evolve.

  • I'm having a hard time figuring out what your answer is to my question of "If there's a creature with a different brain structure from humans, how could we go about figuring out what they feel?" This is helpful expository information, but it would be nice to see it tied into an answer, even if that answer is "We can't." or "Do something that will kill it and that will always make it feel bad."
    – Pro Q
    Apr 7, 2020 at 17:59
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    @ProQ Just added the first line. "Do something that will kill it and that will always make it feel bad" not correct: give a mouse a cocaine overdose and it'll "feel" it good until it dies...
    – RodolfoAP
    Apr 8, 2020 at 14:14

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