Categorization is a innate human function (other animals engage in categorization as well). When we see an animal, listen to a piece of music or read a book we consciously or subconsciously categorize them.  For example, upon hearing a song we might think of it as “rock” and within rock, as “classic rock” or “heavy metal” or “alternative rock” or “yacht rock.” How do we do this?

For over 2,000 years our understanding of how we categorized was the “Concept Theory” which had been formulated by Plato and Aristotle.  The Concept Theory says that categories have a set of conditions or definitions and we place things in categories by referring to those conditions.  For example, the set of conditions for being classified as a bird are:  having feathers, having wings, a beak and being able to fly. Another example: heavy metal music is defined by loud, distorted electric guitars, a strong drumbeat, use of power chords and vigorous vocals.

Concept Theory makes a lot of sense.  So what? Why is this interesting? Because there is another, and arguably more accurate, way of explaining how humans categorize:  Prototype Theory.

Prototype Theory was proposed by Eleanor Rosch in the 1970s. She saw problems with the rigidity of Concept Theory and proposed that something can be more or less of a category member and we decide that based on prototypes.

Take the bird example above.  A robin fits the conditions for a bird very well. However, penguins, ostriches and chickens don’t fit quite as well. Thus, we might say that a penguin is less bird-like than a robin but still a bird.  A Labrador is more dog-like than a Shih Tzu. Same for heavy metal – Motley Crue is more like heavy metal than Bon Jovi. Even though the song “Beat It” by Michael Jackson has distorted guitars and Eddie Van Halen plays on the song it isn’t anything close to heavy metal. Another example: a dining room chair is more chair-like than a chaise lounge chair. A Ferrari is more like a “sports car” than a Tesla Model S (even though the Tesla may be faster).

What prototype theory recognizes is that categories are fuzzy and can be overlapping. Membership in a category doesn’t require that you have all the characteristics of the group.  Instead, things are judged to be more or less representative of the category based on our prototypes of that category. Often, our “prototypes” are averages of similar things based on our experiences, but sometimes there is one shiny example in our heads of a prototype.  For me, here is the exact prototype of a cow:

Thus, when I came across the below “cow” in Isle of Skye, it wasn’t clear to me what it was for awhile – its a ways away from my prototypical cow.

This is a huge and interesting topic with a lot of philosophical and logical issues. Read more here: http://www2.denizyuret.com/bib/rosch/rosch1999principles/QL-75cadM2D.pdf