Under OR aggregation, adding defining features must expand a concept’s extension, not shrink it.

Evidence

However, one can contrast this well-known view about the relationship between intension and extension with the almost completely ignored principle that with the best shot, maximum, OR, or union as the concept structure, extension increases: As one increases intension in the sense of increasing the number of best shot defining characteristics, the extension—number of empirical cases—goes up. If we replace AND in the classic relationship between intension and extension with OR then the number of empirical cases must remain the same or go up. — Gary Goertz, Social Science Concepts and Measurement, 1356

Categorization

• SEED: Angle: ‘The Forgotten Half of the Ladder’ — a methodological essay on how the intension-extension literature silently assumed AND and thereby hid the possibility of extending concepts by adding dimensions.
• DEEPTHINKING: Inverts the single most-cited rule in comparative-methods concept formation, and it reframes conceptual stretching as a structural choice rather than a vice.