If 'what X is' necessarily invokes extrinsic efficient causes, then definitions of natural kinds would be observer-relative and indexed to contingent causal histories rather than expressing necessary properties.

?Rate how convincing each reason is below to see the overall strength.

1 reason for

1 reason against

Reasons For

1 perspective

Reason for

1 perspective

Reason against

Based on where you are in your exploration

contingent(De Interpretatione 12–13): Equated with 'possible'; on the two-sided interpretation, contingency excludes necessity (possibility implies non-necessity).
definitions of X(logic and language): An explanation of what something essentially is—the core features that make it that thing and not something else.
extrinsic efficient causes(metaphysics and causation): External factors or forces that make something happen or cause it to be what it is, rather than something about its internal nature. Think of how a statue's shape is caused by the sculptor's actions (external) rather than by the marble itself.
natural kinds(Water is offered as a paradigm example of a natural kind individuated by microstructure): Categories of things in nature that share an essential microstructure, used to ground essentialism about species and substances
necessary properties(Contrasted with impossible properties; both are said to supervene trivially on any property.): Properties that everything has necessarily, such that no possible thing can lack them.
observer-relative(metaphysics and epistemology): Something that depends on who is looking at it or how they perceive it, rather than being the same regardless of who observes it.

2 topics