Concepts defined only by necessary conditions cannot support positive claims about cases.

Evidence

Depending on the (con)text it may be reasonable to assume that, in the absence of any specific claims about sufficiency, all the necessary conditions are jointly sufficient. It must be stressed that giving “minimum” sets of dimensions is theoretically and methodologically incomplete. A complete concept structure must include sufficient criteria. If we are to say anything positive about cases we must have sufficient conditions. — Gary Goertz, Social Science Concepts, 255

Categorization

• DEFINE: Clarifies the distinction between necessary and sufficient conditions in concept structure, and why minimum dimension sets are incomplete.
• XREF: Connects to any prior chapter material on necessary/sufficient condition structure as the standard for concept definition.