Definitions based on underlying structure explain more than those based on surface qualities.

Evidence

For example, we can ask what “copper” is. One property of copper is its reddish color. However, we would not consider a definition of copper based on its color very adequate for most purposes; much better would be a conceptualization of copper based on its atomic structure. The atomic structure of copper is a better and more useful basis for thinking about copper than an approach based on qualities like its redness, because its atomic structure explains more about its causal powers and properties, e.g., the ability to conduct electricity. — Gary Goertz, Social Science Concepts and Measurement, 513

Categorization

• DEFINE: Clarifies what makes one conceptualization of a thing better than another: explanatory power over causal properties, not mere descriptive fit.
• XREF: Connects to essentialism-versus-operationalism debates and to measurement theory’s preference for latent constructs over observed indicators.