Only changes to an object’s essential properties alter what kind of thing it is.

Evidence

This distinction goes back at least to Locke, but probably all the way to Aristotle. Both philosophers distinguished between “essential” and “superficial” characteristics of an object. Change in essential char­ acteristics constituted a change in kind, while changes in superficial traits—“nominal” in Locke’s terminology—did not result in a change in kind. For example, a change in a democratic regime from presidential to parliamentary does not entail a change from a democratic to au­ thoritarian regime. However, take away essential properties, say, civil rights, and the regime changes its fundamental character. To go back to chemistry, a change in temperature of an element does not mean a change in its classification in the chemical table, while a change in the number of electrons does. — Gary Goertz, Social Science Concepts, 32

Categorization

• DEFINE: Lays out the realist/essentialist view of concepts: essential vs nominal traits, and why only the former constitute a change in kind.
• XREF: Echoes the existing kept claim that ‘valid purposes in two distinct legal contexts do not justify merging them’ — both rely on preserving a principled distinction rather than collapsing categories.