Does the term “biped” or “quadruped” refer to the incidental characteristics of a creature, or the paradigmatic characteristics of that kind of creature?

Would a human amputee be a biped because humans in general are bipeds by nature?

  • Is this the Riddle of the Sphinx? Isn't a human a quadruped, then a biped then a triped? – Juhasz Mar 27 at 15:56
  • Serious question. – Resting in Shade Mar 27 at 16:12
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    Opinion only: "biped" refers to the species, not the individual creature. "Humans are bipeds" is acceptable, "Steve is a biped" sounds downright weird. – AndyT Mar 27 at 16:29
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    This is much more a philosophical question than one to do with the English language. At what point does a boat (after being modified or taking damage) cease to be a boat and become just a collection of material that may or may not float? – Jason Bassford Mar 27 at 17:36
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    Also worth asking: Is a human being in a Big Bird costume a featherless biped? – Sven Yargs Mar 27 at 22:09

A biped (Oxford) is An animal that uses two legs for walking. Other dictionaries use almost identical wording. An animal (human or otherwise) that lacks legs can't use them, so isn't a biped.

That seems clear enough but actually it's more of a philosophical question than a semantic one. I'd could be tempted to agree with the dictionary and go on to say your hypothetical amputee is a member of a bipedal species, but not a biped themself. But what about someone who possesses legs but has lost the use of them? Or, to take it to an extreme, even someone who's metaphorically legless - i.e. has temporarily lost the use of their legs through drinking?* Or go the other way - someone born without lower limbs.

Humans are, after all, generally defined as bipeds, and I certainly wouldn't want to make the argument that physical disability (or even drunkenness) makes someone less human.

That, even if only on the grounds of inclusion, would suggest that the question's "paradigmatic characteristics" basis would be a good one to use. Even so, would we extend these inclusive arguments to creatures incapable of understanding them - an amputee ostrich for example, or an amputee robot (autonomous or otherwise)?

I'm afraid there is no clear answer; there may be a most suitable answer for a given situation, and I hope this answer has given you some information to make that choice.

*"No longer bipedal" would actually be a nice euphemism for falling down drunk.

  • And what if the potentially bipedal animal chooses not to walk - it has two legs that could be used for walking, but aren't? And what if the animal walks with two legs, but they're someone else's legs? Or what if the animal walks with two piano legs? Isn't deconstruction fun? – Juhasz Mar 27 at 19:29
  • A quadruped also uses two legs for walking. It also uses three. It also uses four. But only some of the time does it walk. – Trevor Reid Mar 28 at 9:15

As "biped" is a scientific description of a particular clade, rather than an individual, all humans are bipeds, regardless of how many feet they actually have or use.

A human being who has lost a leg would best be described as "one-legged".

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