Editing Concept (section)

==== Arguments against the classical theory ====
Given that most later theories of concepts were born out of the rejection of some or all of the classical theory,<ref name="concepts core readings"/> it seems appropriate to give an account of what might be wrong with this theory. In the 20th century, philosophers such as Wittgenstein and Rosch argued against the classical theory. There are six primary arguments<ref name="concepts core readings"/> summarized as follows:
* It seems that there simply are no definitions—especially those based in sensory primitive concepts.<ref name="concepts core readings"/>
* It seems as though there can be cases where our ignorance or error about a class means that we either don't know the definition of a concept, or have incorrect notions about what a definition of a particular concept might entail.<ref name="concepts core readings"/>
* [[Willard Van Orman Quine|Quine]]'s argument against analyticity in [[Two Dogmas of Empiricism]] also holds as an argument against definitions.<ref name="concepts core readings"/>
* Some concepts have fuzzy membership. There are items for which it is vague whether or not they fall into (or out of) a particular referent class. This is not possible in the classical theory as everything has equal and full membership.<ref name="concepts core readings"/>
* Experiments and research showed that assumptions of well defined concepts and categories might not be correct. Researcher Hampton<ref>{{cite journal |last1=Hampton |first1=J.A. |title=Polymorphous concepts in semantic memory. |journal=Journal of Verbal Learning and Verbal Behavior |date=1979 |volume=18 |issue=4 |pages=441–461|doi=10.1016/S0022-5371(79)90246-9 }}</ref> asked participants to differentiate whether items were in different categories. Hampton did not conclude that items were either clear and absolute members or non-members. Instead, Hampton found that some items were barely considered category members and others that were barely non-members. For example, participants considered sinks as barely members of kitchen utensil category, while sponges were considered barely non-members, with much disagreement among participants of the study. If concepts and categories were very well defined, such cases should be rare. Since then, many researches have discovered borderline members that are not clearly in or out of a category of concept.
* [[Eleanor Rosch|Rosch]] found typicality effects which cannot be explained by the classical theory of concepts, these sparked the prototype theory.<ref name="concepts core readings"/> See below.
* Psychological experiments show no evidence for our using concepts as strict definitions.<ref name="concepts core readings"/>