Our space explorers got some friends together to try to form a galactic union. Most inter-species unions would be an empire where a few species are controlling lots of others, or a partnership between a few species like they have now. They are actively trying to avoid both of these. They quickly run into a problem; how to determine if a being is a person? Right now, they have the following rules, in no particular order:

  1. Humans and similar rubber-forehead-esque aliens are people. As elemtilas pointed out, some people today have not sorted this out, but our travelers have, in no small part due to the species in rule 2.
  2. A species of near-perfect altruists are people. This is relevant, because they will not defend themselves in certain situations e.g. won't save themselves if it means other will die.
  3. Bio-mechanical beings are people, such as cyborgs, people with prosthetics, and some species who evolved to be mostly mechanical.
  4. Species with incomplete free will are people. For example, a species with a hive mind, or a species where individuals higher up can mentally force those beneath them to do things. However, individuals have to exhibit individuality, or the species is one individual.
  5. Species that communicate in "unusual" ways and live for varied periods of time are people. For example, bug-like aliens who communicate solely via pheromone and live for short periods of time, are people.

However, the following are not people:

  1. Food, like cows, corn, and their alien counterparts, are not people.
  2. Species without any individuality at all.
  3. Species without civilization.
  4. Species where the only desire of the entire populous is the pain and destruction of others.

There are three big problems with the current system. First, the "not people" rules, are incomplete. Second, the "are people" rules are incomplete and the connection between them isn't clear. Finally, what counts as communication is foggy. It's fine to not have a language if you have telepathy, but you can't regard the communications of a dog as valid, even though they do communicate through body language and sound. (they are still good boys though.)

This group needs a simple, objective (or near objective), guidelines for determining the person-hood of a species that fits as many of their current rules as possible

The rules they have made already can be changed, but doing so may result in some unfortunate consequences, like telling someone they can't eat bacon anymore because pigs are people, and so is the guy who wants to eat them. It could also result in telling someone already in their union "actually, you don't count."

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented Jan 26, 2021 at 3:41
  • $\begingroup$ True and tested Solus Mordin's method: "No tests on species with members capable of calculus". If they can do math - they're definitely people. $\endgroup$ Commented Feb 11, 2021 at 17:53
  • $\begingroup$ Why are you ruling out cows? They have individuality and communicate... $\endgroup$
    – Questor
    Commented May 3, 2023 at 20:45

7 Answers 7


I think you're overthinking things, or at least putting your thought into too broad an area when you already found the area you should be focused on. Reading all your rules and concerns, it all seems that your authorial concern to boils down to the potential of how well you can communicate with them.

So really, there's only one rule:

  1. You think you can meaningfully communicate with them.

So it seems to me the real question is how to judge the potential for communication. Similar to something like a Turing test or just having your characters go by their feelsies.

However it is very easily arguable that the communication thing is very anthromorphic self-serving definition of what constitutes a person and not very universal at all. However, if your goal of defining personhood is to form a galactic union then it does not matter how intelligent they are or how much they qualify under some other definition of people when you can't communicate with them to begin with so for these purposes other definitions are moot.

When you have no chance of communicating or understanding each other, the only purpose of a universal definition of personhood is whether you can genocide them or not.

Now, unless I am reading you wrong, there seems to be a dichotomy between what you want your space explorers to be as an author and what your space explorers actually seem to be based on what you've told us about them. You seem to want your space explorers to be be determining genuine personhood out of good faith, but the rules you presented us with indicate that your space explorers have more nefarious self-serving ambitions.

Your pre-existing rules:

Species where the only desire of the entire populous is the pain and destruction of others.

implies that effective communication is the real concern for your space explorers rather than whether or not something is truly a person. Because under that rules, it doesn't matter how intelligent they are. Ironically, it doesn't even matter that you can communicate with them. All that matters is that your communication isn't able to convince them out of the universal desire to destroy you (heck, they don't even have to want to destroy. All they have to want to do is enslave you for the purposes of torture.)

And this next barbaric rule takes that to another level:

Species without civilizations are not people.

This rule implies that if they are incapable of cooperation in a manner from which you can benefit then they are not people. It also defines organisms with extremely capable natural abilities and have little need of artificial augmentations as non-people.

Together, these two rules basically say that they are only people if you can communicate with them and cooperate with them. In other words, people are only people if you can benefit from them and but can't reap such benefits by farming them.

Species without any individuality at all.

This rule implies that if they are hive minds, or simply too different from our understanding then they are not people. Also, to me it seems that species without individuality are farmable which reinforces what I said previously.

Now assuming you genuinely do want to determine personhood out of good faith, there is a small gap in this singular communication rule and that is if a race is clearly intelligent, yet cannot be communicated or understood, but peaceful and not destructive (lest they be classified as pests). The implication here is that they are both unable to protest mistreatment and also unable to defend or assert themselves.

But consider that even a bacterium can assert itself and try to prevent its own destruction. On these grounds you could probably argue such an organism, let alone a civilization, cannot exist.

At this point, you might try and bring up this:

A species of near-perfect altruists are people. This is relevant, because they will not defend themselves in certain situations e.g. won't save themselves if it means other will die.

But that's rather irrelevant. Just because you're altruistic doesn't mean you can't protest or assert yourself. Not to mention that a race could be considered bloodthirsty but still consider themselves to be altruistic...all they have to do is not to consider anyone else as people.

As an addenum, there is also the issue of how you define civilization.

I was previously hinting that the definition I was using for civilization includes mass cooperation as a key element (which is really important if you're trying to form a galactic union). But unless you want to qualify ant colonies, you would probably disagree that this is sufficient criteria. Another criteria which is often mentioned is the passing on of knowledge between generations. If you then add to tool-building to this, then this is civilization as we humans know it.

But these criteria have serious flaws in that they assume assume reproduction (if not necessarily a finite lifespan), and a social structure (i.e. multiple individuals frequently interacting with each other rather than existing alone). These criteria disqualify existences (not societies because there is no society) such as hiveminds or a centralized AI where a single entity runs everything for perpetuity.

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    $\begingroup$ "Species without civilizations are not people." you also have the problem that you now have to define civilization. $\endgroup$
    – John
    Commented Jan 23, 2021 at 15:38
  • $\begingroup$ @John Indeed. See addenum. $\endgroup$
    – DKNguyen
    Commented Jan 23, 2021 at 19:55
  • $\begingroup$ Right. If it talks like a duck, then ... $\endgroup$ Commented Jan 24, 2021 at 15:34
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    $\begingroup$ @RBarryYoung then you enslave it or exterminate it because ducks have neither civilization nor sufficient communication ability and are therefore not people. $\endgroup$
    – DKNguyen
    Commented Jan 24, 2021 at 21:42

Simple answer: Ask them

Ask a representative from the species in question:

"Do you understand the concept of personhood, and are you a person?"

Any sentient being should be able to answer this question in some form. A farm animal almost certainly cannot. Even a hive mind would be able to answer for its collective as "Yes, we are a person." So in that case, you would afford personhood to the hive mind as a whole, but not any individual member of that hive mind. That would lead to the interesting case where murdering a member of a hive mind would be the equivalent of injuring an individual from a non-hive species. You would have a moral and legal justification for valuing an individual from one species more than an individual from another.

But this probably shouldn't be your only question. It's very important to understand if the being has an understanding of the theory of minds, otherwise you will not be able to effectively interact in any meaningful sense as sentients.

So your next question should be:

"Do you have a concept of theory of mind, and do you recognize it in others?"

Any sentient being should be able to answer this in the affirmative as well, since it is one of the requirements for sentience. If your being has the concept of personhood, but cannot recognize it in others, then it is arguable whether it truly understands the concept of personhood. If it doesn't, it shouldn't be afforded the same rights you would a person, as it is incapable of understanding the rights and responsibilities of personhood.

Your final question is also quite important:

"Do you have a concept of morality, and does it guide your actions?"

A farm animal may in some way be able to answer the first two questions, but it definitely can't answer the third. Ultimately, animals act completely on survival instinct, and lack any sense of morality. It isn't morally wrong for a tiger to prey on a cow, but the cow certainly doesn't want to be eaten. However, the cow doesn't understand the concept of "right and wrong;" it's merely a survival instinct that makes it not want to be eaten. It's not even "wrong to the cow" to be eaten, as the concept of "wrong" doesn't exist. Likewise, it's not "right" to the tiger to eat, nor does it feel guilt for doing so; it just does so as a matter of survival.

Similarly, any being that cannot understand morality and empathy cannot complain when the completely amoral act of being eaten happens to it. The reason a sentient being sometimes doesn't want to eat animals is because of this empathy, and it's that empathy, not the fact that the sentient being doesn't want to be eaten, that is the reason you don't eat sentients.

If your being is sentient, but lacking in a concept of morality, affording it personhood would be very dangerous, as its motives would not be driven by any sort of empathy, and it could exploit its personhood to harm others.

Giving this kind of being personhood would simply result in crimes against your other sentients. It is arguable that a being completely devoid of empathy is undeserving of empathy itself, and it is also arguable that personhood requires empathy, or that it is at least an obligation of any "person" (like a sort of noblesse oblige). This is essentially why we deny criminals their "personhood" by incarcerating them, as they have neglected the responsibility that comes with being a person, and ideally the ultimate goal of such incarceration would be to instill the understanding of that responsibility and to create a sense of empathy.

Ultimately, a being completely lacking in empathy would be the epitome of "chaotic evil."

Beings like this are the reason we have punishments like the death penalty and life imprisonment, namely because such a being is unpredictable and has no redeeming qualities. Obviously, you don't want this kind of being as a member of your Galactic Society.

Note that a being driven purely by logic will still develop a form of "logical empathy." The Golden Rule itself is quite logical. A logical being would understand theory of mind, and would have no reason to believe it unreasonable that what it does to others could be done to itself. It is almost tautologically apparent that if you want to do violence to others, you should expect it to be done to you, and any logical being should arrive at this conclusion rather quickly.

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    $\begingroup$ A parrot that answered "yes" to all questions would pass that test. A human who had no word for "concept" in their language might not. $\endgroup$ Commented Jan 23, 2021 at 6:43
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    $\begingroup$ Let alone a parrot, the Linux utility program yes would pass that test too. $\endgroup$
    – March Ho
    Commented Jan 23, 2021 at 13:55
  • 2
    $\begingroup$ Social animals actually have morality, even vampire bats have morality, that is just a check to see if they are social. morality is such a low bar there are hundreds of species on earth that have it. $\endgroup$
    – John
    Commented Jan 23, 2021 at 15:41
  • 1
    $\begingroup$ @stix 1. nature.com/articles/308181a0 2. sciencedirect.com/science/article/abs/pii/0162309588900155 $\endgroup$
    – John
    Commented Jan 25, 2021 at 17:32
  • 1
    $\begingroup$ @stix 4. sciencedirect.com/science/article/abs/pii/S096098222030110X 5. royalsocietypublishing.org/doi/full/10.1098/rspb.2012.2573 it sounds more like you are assuming morality requires more than it does. Bats display very complex reciprocal altruism between non-related individuals, including tracking and rewarding favors and tracking and punishing selfishness. $\endgroup$
    – John
    Commented Jan 25, 2021 at 17:33

The idea that food is not people, and the idea that a species without civilziation is not people, are likely to permitt many atrocities.

Perhaps you might have heard about members of the species Homo sapiens who were cannibals. People have been willing to eat people who were members of their own species, and some groups did it a lot. I can imagine that if some alien species are edible for other alien species, some of those alien species might eat edible alien species, even when they don't have the additional motive of denying personhood to another species and being free to take over their planet by eating those aliens.

I note that in the future, when humans might propose a rule that food is not people, aliens might note that some humans are still eaten by animals on Earth - at the present hundreds or thousands of humans are eaten each year. So various aliens might decide that humans are food and not people and invade human space.

And the idea that beings without civilzation are not people is also bad. Homo sapiens was a species without civilzation for hundreds of thousands of years. And similar species existed for hundreds of thosuands of years, maybe a few million years, before that. And sometimes two or more of those prehuman tool making species of hunter-gatherers shared the planet Earth. And many people find it easy to believe that some of those species ate members of other such species more or less often. So every prehistoric tool using primate species, including Homo sapiens for hundreds of thousands of years, would be doubly excluded from personhood due to being food that is uncivilized.

The Square Cube law's answer said that the requirement to be civilized to be considered people would let a lot of people be defined as non people:

Because this ensures that species which are on the way to civilization are game. We wouldn't like this to be imposed upon us if the aliens landed on Earth around the time we were hunting mammoths.

And The Square Cube law seems to assume that mammoths, mastadons, and other proboscideans were not people, even though that is not entirely certain.

It is certainly possible that one or more species of apes, and one or more species of proboscideans, and one of more species of cetaceans, are intelligent enough to count as peaople. So the current number of intelligent species on Earth could be somewhere between one and about one hundred, even though only one of those species is civilized.


Drop this:

species who's only desire is for the destruction and the pain of others.

Some humans are like that. You would be condemning the whole human species into non-people status because of a few idiots. The way to solve this problem is more complex.

Also drop this:

Food, like cows, corn, and their alien counterparts, are not people.

Because there is always the possibility that one species might start preying up on another to remove their people status.

And then drop this:

Species without civilization.

Because this ensures that species which are on the way to civilization are game. We wouldn't like this to be imposed upon us if the aliens landed on Earth around the time we were hinting mammoths.

Second, the "are people" rules are too complex and incomplete.

No they are not complex - I could probably explain this to an eight-year-old and they would understand it. They could even start classifying the alien species in Star Wars into people and not people.

And of course these will always be incomplete. Suppose at some point AI's, energy beings, crystal forms of life etc. come into play. If they communicate through verbal means they wouldn't be able to use rule #5, the fallback option.

I think a good catch-all rule should be: if an individual is capable of requesting political asylum and/or inclusion into the index of peoples, then that individual's species as a whole are people.

  • 2
    $\begingroup$ Very good! I need to make some edits to my question. The reason I'm not accepting your answer is because, how do you define such a request? If it's a language, that's easy, the request is legitimate. But what about a squirrel trying to get onto your ship? It wants to be on your ship, that much is clear. But I wouldn't say that makes it a person. Again, very useful, +1. $\endgroup$ Commented Jan 22, 2021 at 21:39
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    $\begingroup$ @RobertSpencer the squirrel might be trying to save its hide, but it is not making a request for inclusion. You could use that as the filter for people. Anyway, even if you did think my answer was to be the accepted one, I think we will see better ones in a few hours :) $\endgroup$ Commented Jan 22, 2021 at 22:15
  • $\begingroup$ "If an individual is capable of requesting political asylum" - that won't work if you don't understand their language. If they have a language, they should already be considered people. $\endgroup$ Commented Jan 23, 2021 at 6:41
  • $\begingroup$ the other problem with using civilization as a requirement is defining civilization. $\endgroup$
    – John
    Commented Jan 23, 2021 at 15:45

The simplest criteria is "can they communicate and converse in a meaningful way about complex abstract hypothetical/fictional concepts". This should be the basic test for your sophonts.

If they can do that they can understand about laws and rules, learn and consider new ways of thought and the situation of other species.

Not the easiest thing to ascertain, it will take some work and time but you want that anyway. If the criteria is too easy to test accidents will happen, species will get missed . The real problem you run in to is intelligence is not a discrete function but a spectrum. We just killed off or outcompeted everything close to us on the spectrum.


Pick a list of

  • functional tasks (eg: Can communicate and make.efforts to bridge communication gaps. Can develop tools)
  • Mental/emotional/cognitive social capabilities (Can comprehend different beings may have different perspectives. Can comprehend and recognise others may be happy/sad/damaged and wish to reduce discomforting experiences and help others long term)
  • social structures (can make decisions as a species and broadly keep them. Can socialise cooperatively or at least agree to not socialise. Can police abberant individuals)

Things like that. For species as a whole not for each individual.

Think what characteristics a species would need to have, to be capable, and wishing, to work in such a way,and what tests would explore those.


Processing power.

This is the answer I have used. My civilization wanted to come up with a broad and easily applicable metric, so they used this.

Human brains have about 300 trillion ( $3 x 10^{15}$ ) synapses. Typical brain activity is in the range of 30 to 100 hertz. So, “sentient” is everything greater than some cutoff, with humankind as a data point at 9 quadrillion to 30 quadrillion operations per second during typical waking activity.

The research I did at the time showed that dogs are about 1/10th this processing speed. Anecdotally, dog mental development tops out at what a 2 year old human is capable of, although dogs develop to that point more quickly than we do. According to the same sources, cats are about 1/10th dogs (sorry cat lovers). Mice, where I decided to draw the line, are about 100 billion operations per second $1 x 10^{11}$.

You can go arbitrarily lower. If actin based signaling is real, trees come in at around 500 thousand, and grass at a few hundred operations per second.

I recommend a broad, clear gap, so that there’s no quibbling about legal distinction.

  • 2
    $\begingroup$ Going anecdotal, I have a dog that can outsmart many of my friends when it comes to simple things (i.e.: not touching live bare wires a second time). I don't think just mere raw brain power is a good measure of intelligence. Also AFAIK elephants and whales have more synapses than we do. $\endgroup$ Commented Jan 22, 2021 at 22:17
  • 1
    $\begingroup$ Good point, but something unintelligent could, in theory, have high intelligence but could not be considered. Imagine an extremely advanced computer with more processing power than a human. However, it exhibits no desire to do anything besides what it is told to. +1 $\endgroup$ Commented Jan 22, 2021 at 22:25
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    $\begingroup$ @TheSquare-CubeLaw humans actually preform slightly worse than chimps in the simplest learning tasks but better at anything more complex. $\endgroup$
    – John
    Commented Jan 22, 2021 at 23:01
  • 1
    $\begingroup$ @The Square-Cube Law And possibly elephants and whales should be considered to be people. See my answer, $\endgroup$ Commented Jan 23, 2021 at 4:29
  • $\begingroup$ Hmm… None of my brain cells have that much processing power, so they're all fair game. That forest, on the other hand… $\endgroup$
    – wizzwizz4
    Commented Jan 23, 2021 at 23:40

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