Full Idea
Is there really an 'ideal bird' that could represent all birds? ...Furthermore a single prototype would give no information about the variability of a category. ...Compare the incredible variety of dogs to the much smaller diversity of cats.
Gist of Idea
There is no 'ideal' bird or dog, and prototypes give no information about variability
Source
Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 3)
Book Reference
Murphy,Gregory L.: 'The Big Book of Concepts' [MIT 2004], p.42
A Reaction
The point about variability is particularly noteworthy. You only grasp the concept of 'furniture' when you understand its range, as well as its typical examples. What structure is needed in a concept to achieve this?