Categorisation and cognitive semantics
In the 1970s the definitional or classical theory of human categorisation – so called because it had endured since the time of the ancient Greek philosophers over 2,000 years ago – was finally called into question. The new ideas that con tributed most significantly to this development are grouped together under the term prototype theory, which emerged from the research of Eleanor Rosch and her colleagues. In fact, ‘Prototype Theory’ was less a theory of knowledge rep resentation than a series of findings that provided startling new insights into human categorisation. In so far as the findings led to a theory, Rosch proposed in her early work that humans categorise not by means of the necessary and sufficient conditions assumed by the classical theory (to which we return below), but with reference to a prototype: a relatively abstract mental representation that assembles the key attributes or features that best represent instances of a given category. The prototype was therefore conceived as a schematic representation of the most salient or central characteristics associated with members of the category in question.
A problem that later emerged was that the view of prototypes as mental representations failed to model the relational knowledge that humans appear to have access to (recall from the last chapter that relational knowledge is one of the properties of encyclopaedic knowledge addressed by Frame Semantics). These criticisms led to further developments in prototype theory. Some scholars argued for a revised view of the prototype, suggesting that the mental representation might correspond to an exemplar: a specific category member or ‘best example’ of a category, rather than a schematic group of attributes that characterise the category as a whole. However, these exemplar-based models of knowledge representation were also problematic because they failed to represent the generic information that humans have access to when they use concepts in order to perform a host of conceptual operations, including categorisation. Indeed, the most recent theories of categorisation assert that a key aspect of knowledge representation is the dynamic ability to form simulations, an idea that was introduced in the previous chapter. Thus, in a number of respects, prototype theory has been superseded by more recent empirical findings and theories. Despite this, there are a number of reasons why a chapter on categorisation in general, and prototype theory in particular, is essential for a thorough understanding of cognitive semantics.
Firstly, an investigation of prototype theory provides a picture of the historical context against which cognitive linguistics emerged as a discipline. The development of prototype theory in the 1970s resonated in important ways with linguists whose research would eventually contribute to defining the field of cognitive semantics. Charles Fillmore and George Lakoff were both members of faculty at the University of California at Berkeley where Eleanor Rosch was also conducting her research, and both were influenced by this new approach to categorisation. For Lakoff in particular, Rosch’s discovery that psychological categories did not have clearly definable boundaries but could instead be described as having ‘fuzzy’ boundaries reflected his own views about language: Lakoff thought that lexical and grammatical categories might also be most insightfully conceived as categories with rather fluid membership. This led Lakoffto apply this new view of psychological categories to linguistic categories (such as word meanings). In this way, ‘Prototype Theory’ inspired some of the early research in cognitive semantics.
Secondly, and perhaps more importantly, although it now seems that proto type theory cannot be straightforwardly interpreted as a theory of knowledge representation, the empirical findings that emerged from this research demand to be accounted for by any theory of categorisation. In other words, the proto type effects or typicality effects that Rosch discovered are psychologically real, even if the early theories of knowledge representation that were proposed to account for these effects have been shown to be problematic. Indeed, a central concern in Lakoff’s (1987) book was to address the problems that early prototype theory entailed, and to propose in its place a theory of cognitive models.
Thirdly, as we mentioned above, Lakoff’s (1987) book set the scene for the development of three important strands of research within cognitive linguistics: (1) Conceptual Metaphor Theory (Chapter 9); (2) cognitive lexical semantics (Chapter 10); and (3) a cognitive approach to grammar that influenced the well-known constructional approach developed by his student Adele Goldberg (to which we return in Part III of this book).
Finally, Women, Fire and Dangerous Things, despite its rather meandering presentation, in many ways defines the two key commitments of cognitive linguistics: the ‘Generalisation Commitment’ and the ‘Cognitive Commitment’. Lakoff’s book took what was then a relatively new set of findings from cognitive psychology and sought to develop a model of language that was compatible with these findings. In attempting to model principles of language in terms of findings from cognitive psychology, Lakoff found himself devising and applying principles that were common both to linguistic and conceptual phenomena, which thus laid important foundations for the cognitive approach to language.
