"As Rosch (1977) has established, we categorize things in terms of prototypes. A prototypical chair, for us, has a well-defined back, seat, four legs, and (optionally) two armrests. But there are nonprototypical chairs as well: beanbag chairs, hanging chairs, swivel chairs, contour chairs, barber chairs, etc. We understand the nonprototypical chairs as being chairs, not just on their own terms, but by virtue of their relation to a prototypical chair." (#60 2135)

"We understand beanbag chairs, barber chairs, and contour chairs as being chairs, not because they share some fixed set of defining properties with the prototype, but rather because they bear a sufficient family resemblance to the prototype. A beanbag chair may resemble a prototypical chair in a different way than a barber chair does. There need be no fixed core of properties of prototypical chairs that are shared by both beanbag and barber chairs. Yet they are both chairs because each, in its different way, is sufficiently close to the prototype." (#60 2138)