On the problem of categorization in linguistics

Categories are defined by a set of essential features

• 
  Peripheral features are not important in defining a category
  

Category membership is determined by the presence of these essential features

• 
  Essential features hold a category together, so all member should have them
  

All category members have equal status

• 
  If all members have the same essential features, they are all equally good representatives of their category
  

Category boundaries are sharp and rigid

• 
  If a concept has all essential features, it is a member of the category; if not, it
  

cannot be a member

• 
  A modern version: componential analysis
  
• 
  A way of formalizing semantic analysis based on essential features
  

MAMMAL
+ℎ𝑎𝑖𝑟

−𝑓𝑒𝑎𝑡ℎ𝑒𝑟𝑠
−𝑒𝑔𝑔_𝑙𝑎𝑦𝑖𝑛𝑔
−𝑤𝑖𝑛𝑔𝑠
+𝑤𝑎𝑟𝑚_𝑏𝑙𝑜𝑜𝑑𝑒𝑑
BIRD
−ℎ𝑎𝑖𝑟
+𝑓𝑒𝑎𝑡ℎ𝑒𝑟𝑠
+𝑒𝑔𝑔_𝑙𝑎𝑦𝑖𝑛𝑔
+𝑤𝑖𝑛𝑔𝑠
−𝑤𝑎𝑟𝑚_𝑏𝑙𝑜𝑜𝑑𝑒𝑑

• 
  Categories are defined by a number of typical examples (exemplars)
  
  • 
    These exemplars will have a number of salient features
    
  • 
    … but there is no expectation that there is an overlap of features
    
• 
  Category membership is determined by the similarity of the member and exemplar memories
  
  • 
    No rules of comparison
    
  • 
    Comparison of essential and non-essential features
    
  • 
    Distance function determines how close the member is to its exemplar
    
• 
  Certain members are more central than others
  
• 
  Categories are not fixed and have no clear boundaries