Collier, David, and James Mahon, Jr. "Conceptual 'Stretching' Revisited: Adapting Categories in Comparative Analysis". The American Political Science Review, Vol.87, No.4 (1993): 845-855.

Collier, David, and James Mahon, Jr. "Conceptual 'Stretching' Revisited: Adapting Categories in Comparative Analysis". The American Political Science Review, Vol.87, No.4 (1993): 845-855.

• Scholars frequently encounter new information and attempt to adapt current categories to that new information, either through the application of one theory to a different field, 'conceptual travelling', or by distorting the definition of a category to make the new information fit, 'conceptual stretching' (845).
• These methods of incorporating new information are absolutely essential in political science, because they make sure that the scholarly community operates with a set number of shared definitions, without which any comparative efforts would immediately collapse (845).
• These ideas of stretching and travelling were originally created by Giovanni Sartori, who wanted them to be used as a benchmark to make sure that political scientists did not water down concepts too much (846).
• The authors note that these concepts of 'travelling' and 'stretching' make sense when discussing the taxonomic and hierarchical models used by political scientists in the 1970s and 1980s, but make less sense applied to modern political science categorizations, which allow for gradients of definition (845).
• For example, the traditional method of thinking about categorization as requiring a set of universally shared traits would not account for the existence of 'family resemblance models', where all members share some of a set of features but none are universal (847), or radial categories, where different members are bound by a common concept expressed in different ways or by different definitions (848).