Family resemblance concepts require sufficient attributes, never necessary ones

Evidence

But for rare exceptions (e.g., Collier’s work), the family resemblance approach to concepts does not appear openly as an alternative to the necessary and sufficient condition one. A good way to think about the family resemblance structure is as a rule about sufficiency with no necessary condition requirements. In a dichotomous setting the family resemblance rule almost always takes the form of “m of n.” The phenomenon falls into the concept category if the number of secondary-level dimensions present exceeds a certain threshold (m). If one takes the necessary and sufficient condition approach to be expressed as “if and only if n characteristics are present” then the family resemblance takes the sufficiency-only form of “if m of n characteristics are present.” — Gary Goertz, Social Science Concepts, 244

Categorization

• DEFINE: Restates Wittgensteinian family resemblance as the formal ‘m of n’ sufficiency rule, which is the workhorse of prototype-style categorization.
• XREF: Connects to prototype and fuzzy-set categorization debates in cognitive science and to Sartori’s classical-versus-radial concept distinction.