The most powerful argument I've encountered for ethical veganism is known as 'Name the Trait'.

Its most rigorous and recent iteration - as described by PhilosophicalVegan.com - runs as follows:

P1) If your view affirms a given human is trait-equalizable to a given nonhuman animal while retaining moral value, then your view can only deny the given nonhuman animal has moral value on pain of P∧~P.

P2) Your view affirms a given human is trait-equalizable to a given nonhuman animal while retaining moral value.

C) Therefore, your view can only deny the given nonhuman animal has moral value on pain of P∧~P

('Trait-equalizability' is defined as something like, "If human moral value can be made identical to animal moral value and the result is that humans still have moral value, that reveals that animals had moral value all along").

Whilst the source for the above material is clearly biased, it does deal with attempted refutations. Whether the refutations mentioned are are adequately addressed and whether there are others that have not been addressed is not clear.

All this being said, it is far more common for the 'Name the trait' argument to take on a more colloquial form, which is usually posed as a question typically expressed as something like:

"What trait(s) do non-human animals possess or lack which justify their torture and killing?".

Given that this is the form the question most often takes in casual settings, I am very interested in any responses and justifications. The question essentially asks how the torture and killing of other animals might be justified given a consistent application of the views which govern how we treat our own species. It is a question which provokes contemplation of one of the most pressing ethical issues of our time.

During in-person debate I have never encountered any successful naming and defending of a trait. A typical, fairly hasty response would be something like, "Other animals are less intelligent", to which one obvious retort is to ask, "Are we then justified in killing a human who does not rise to a certain level of intelligence? If so, what is this level of intelligence?".

Among the traits which might be named are those listed by PhilosophicalVegan.com. I have duplicated them below for quick reference, via links which summarise and provide refutations of the argued-for trait.

Species maximum, Species normalcy, Has moral value, God's Permission, Soul, Legality, Social Contract, No Reciprocation, Group Membership, History/Tradition, Bred To Die, Food Chain/Naturality,Not Human, Low Intelligence, Civilization/Culture, Moral Agency, No Personhood, Sapience, No Technology, Dignity, No Potential For X, Utility, Nutrients, Quality Of Life, Pleasure/Preference/Whim, My Apathy/Nihilism, Futility, Mathematics, Language, Literacy, Unspecified Differences, All Exact Traits


3 Answers 3


Lacking an impartial observer, humans have set a standard for themselves.

Are there such abrupt gaps in traits between mammals at least? No, this is a fact.

Are there differences (in degree)? There are, a fact as well.

Should we act (discriminatory) even on minor differences in degree? Maybe sometimes (eg. we can award someone the Olympic medal if he is only faster by one millisecond, we can award someone the grandmaster title even if her difference is one ELO point, ..) . But the issue is about the "in principle" status.

The same way that differences in degree between humans are mostly ignored in principle (as necessary variation), the same way those differences can be ignored for non-human animals (eg mammals). There is no obstacle of logical argument to this.

Humans have created mass societies where some fundamental rights are absolutely necessary to be guaranteed for those societies to exist, to function and not crumble in pieces.

So humans are in a sense "forced" to grant rights between themselves, so that mass cohabitation is possible.

On the other hand non-human animals are not cohabitants of human mass societies and moreover serve as food and clothing. If they are in pain or violated human society will not crumble under the burden. Thus this "practical incentive" to grant similar rights is lacking.

(Sidenote: I stand for animal rights)

  • Good argument. Although, in many cases enslaved groups could not effectively demand rights. So ‘practical incentive’ or ‘forced by mass cohabitation’ are slippery here. What we have seen, is societies with rule-of-law like habeus corpus largely succeed more, & those behaviours spread. You could argue on the same basis, that countries with better animal rights succeed more. China is succeeding in many ways, without a rights discourse of the Western kind, challenging this argument further.
    – CriglCragl
    Commented Jun 1, 2022 at 0:14
  • @CriglCragl, yes, it is slight generalization. It does not mean that every state recognises or follows exactly a fixed set of rules. Also during the course of history, groups have struggled for having (more) rights recognized and have succeded. But still some things need to be guaranteed for every society, even though they are constantly re-interpreted and re-negotiated.
    – Nikos M.
    Commented Jun 1, 2022 at 8:19
  • It’s interesting to consider the Aztec state. Social contract theory gives a better account I’d say, than rights as required by social circumstances and so magically appearing.
    – CriglCragl
    Commented Jun 1, 2022 at 10:20
  • Of course social contract theory is relevant. I guess you mean human sacrifices in Aztec society, but this can be a long discussion for comments.
    – Nikos M.
    Commented Jun 1, 2022 at 13:17
  • As a short note: human sacrifices is a relatively recent and most importantly short-lived phenomenon in the long history of humankind. The overwhelming majority of humankind history and prehistory is foreign to it (as for other animals as well)
    – Nikos M.
    Commented Jun 1, 2022 at 13:34

"Name the Trait" is not an argument, but a rebuttal tactic against the special pleading argument that humans are unique in the animal world. For any claimed rationale for humans to be treated uniquely, the Vegan site correctly points out this is an analog gradated feature, and humans are NOT unique.

The original justification of human uniqueness presumes that humans are valid subjects of moral consideration, and all humans are basically equal in this respect. The vegan argument you cite, then makes the claim that because humans and animals do not have a step function difference on any of these supposedly morally relevant traits, then all animals should be treated equally with all humans.

However, the lack of a step function, does not justify the conclusion leapt to by the Vegan argument.

There are moral differences between humans, and there are times that we should act on those differences. Trolley type questions, which are in general very poor moral tools, do at least help clarify this. Children vs adults on different trolley tracks, psychopaths vs budding Nobel prize nominees, etc, where non-ideological people tend to agree that one type of human should be treated as more valuable than another, show that "treat identically" is a PRAGMATIC conclusion, based on the difficulty of doing that kind of sorting among us humans, not a moral one.

The analog differences between us humans are morally relevant, therefore the analog differences between us and animals are also relevant, and as they are more pronounced, and easier to discern, it is far more appropriate to act on them. Therefore, sending the trolley down the track with 150 dog ticks rather than two children, is an entirely moral thing to do.

Moral consideration should not always be the same for all individuals, be they of the same or different species. WHAT the traits are that drive degrees of moral consideration are not 100% agreed to, nor is their measurement and method of application of differential consideration fully agreed to. But anyone who wants to send a trolley car down the track with two children rather than 150 dog ticks, is a danger to have making any moral decision in our world.

  • Although you correctly uncover pragmatic reasons for behaving such and such, further down your answer used obscure and unnamed moral rules.
    – Nikos M.
    Commented May 31, 2022 at 21:04
  • If there is a difference of consideration between members of different species, which the discussion supports, then there is appropriate difference in moral behavior, whether one uses utility, rights, virtues, or basically any other ethical approach. How to do such differential weighting, and what "traits" should be used for such weighting, is in dispute. That does not change the conclusion that one can and should make distinguishment between species.
    – Dcleve
    Commented May 31, 2022 at 21:49
  • I see the point, but this does not exclude a minimum set of rights common to all.
    – Nikos M.
    Commented May 31, 2022 at 21:52
  • 1
    @NikosM. See my answer to this question: philosophy.stackexchange.com/questions/91428/…
    – Dcleve
    Commented May 31, 2022 at 22:17
  • These are classic arguments that have their merit. But it doesn't have to be all or nothing. @Dcleve
    – Nikos M.
    Commented May 31, 2022 at 22:51

The argument is also known as the "Argument from marginal cases". It's called "Name the trait" in less academic media like YouTube. It is discussed a bit on sites like:

Based on those sources, the argument seems an important one in the philosophy of animal rights. The most common objections mentioned in those sources seem all already covered in the PhilosophicalVegan.com wiki site linked in the question.

Outside writing on animal rights specifically, the argument seems not mentioned much, and it does not seem to be influential to the topic of ethics in general. This indicates that the argument may be a noticeable rhetorical means, but not a useful contribution to philosophy.

In it's purpose it's similar to the trolley problem, with certain animals on one side, and certain humans on the other side. Like the trolley problem, it is maybe not designed to have a solution, but to provoke thought.

It cuts many ways though, as one might ask what trait our pets possess that we spend more money on pet food than on fighting human famine in Afrika.

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