Argument from marginal cases

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The Argument from Marginal Cases is a philosophical argument regarding the moral status of animals. Its proponents hold that if animals do not have direct moral status due to their lack of rationality, then neither do other members of society such infants, the senile, the comatose, and the cognitively disabled. The "moral status" may refer either to a right not to be killed or made to suffer, or to a general moral requirement to be treated in a certain way.

1 Proponents
2 Criticism
3 See also
4 References
5 External links

[edit] Proponents

In recent times it has been famously put forward by Peter Singer, however Daniel Dombrowski claims it can be traced back to Porphyry in the third century AD.

[edit] Criticism

A counterargument is The Argument from Species Normality coined by David Graham and proposed by Tibor Machan. In considering the rights of children or the disabled, Machan uses the analogy of a broken chair:

...classifications and ascriptions of capacities rely on the good sense of making certain generalizations. One way to show this is to recall that broken chairs, while they aren’t any good to sit on, are still chairs, not monkeys or palm trees. Classifications are not something rigid but something reasonable. While there are some people who either for a little or longer while – say when they’re asleep or in a coma – lack moral agency, in general people possess that capacity, whereas non-people don’t. So it makes sense to understand them having rights so their capacity is respected and may be protected. This just doesn’t work for other animals.^[1]

David Graham interprets this to mean that if most of a species' members are moral agents then any member has the same rights and protections as the species. In brief, "The moral status of an individual depends on what is normal for that individual’s species."^[2]

A related counterargument from Roderick Long is that a being can obtain moral agency by developing a rational capacity, and from thereon has full moral agency even if this capacity is lost or diminished:

That is why a cow has no rights, though a human being reduced to the mental level of a cow does have them. There's something wrong with the human; there's nothing wrong with the cow. One might say that in the case of the cow-minded human, there's a blank spot where her moral agency is supposed to be, and someone else can step into that blank spot and act as an agent on her behalf. But in the cow there's no blank spot.^[3]

James Rachels has responded to Machan that if one adopts the idea that individuals of a species must be treated according to what is normal for that species, then it would imply a chimp that somehow acquired the ability the read and write should not enter a university since it is not "normal" behavior for a chimpanzee.^[4]