Family resemblance concepts can gain extension by adding attributes rather than losing them.

Evidence

The fly in the ointment is that this all depends on the necessary and sufficient condition structure. As we shall shortly see, if one uses the family resemblance structure one can get the opposite relationship: extension increases with intension. — Gary Goertz, Social Science Concepts, 491

Categorization

• QUESTION: How does the mechanism work — does adding prototype-adjacent attributes recruit new members into the category rather than shrinking it?
• SEED: Angle: ‘The Law of Inverse Variation Has an Asterisk’ — why the classic intension/extension tradeoff only holds under necessary-and-sufficient definitions.