A conceptual framework for “updating the definition of pain”
They postulate that a definition needs to “describe a thing according to its (…) essential and fundamental properties.” Further, they argue that the advances in the understanding of pain as a biopsychosocial phenomenon call for an update of the current definition. Thus, they suggest defining pain as “a distressing experience associated with actual or potential tissue damage with sensory, emotional, cognitive, and social components.” We appreciate Williams and Craig's comment on the problems associated with the current definition of pain and congratulate them on their comprehensive presentation. Nevertheless, we wonder whether simply adding some new descriptors (as suggested by adding “with sensory, emotional, cognitive, and social components”) to the current definition will help overcome its limitations.
When one tries to capture the essence of a term, one not only wants to know what all terms of this type have in common but also know what connects only these terms with one another and what distinguishes them from other terms and makes the given term what it is. Such an analytic approach necessarily results in a reductive definition in that a complex term (definiendum) is explained by simpler and more fundamental terms (definientia). A classic example for such a reductive definition is offered by defining the term “tomcat”2: A “tomcat” can thus be defined as follows: An animal A is by definition a “tomcat” if (and only if) A is (1) cat, and (2) a male. A tomcat is necessarily a cat (to be a cat is a necessary condition for an animal to be a tomcat). But for a given animal being to have the attribute “cat” is by itself not yet sufficient for this animal being a tomcat. For a tomcat is (likewise necessarily) also a male. These are 2 necessary conditions for a given animal to be a tomcat. While “being a tomcat” is a sufficient condition for a given animal being to be a cat and/or a male, none of these 2 conditions is sufficient by itself for this animal to be a tomcat. Thus, a comprehensive unambiguous definition is based on clear unambiguous statements of necessary and sufficient attributes of the term to be defined.
This means that, to find out what the essence of pain is, ie, to find out what applies to all cases of pain and only to these, one must search for the individual necessary and jointly sufficient conditions for pain. Such a logic-based approach can provide a fruitful conceptual framework to develop an appropriate definition of pain in the future.