Full Idea
It is plausible to suppose that the world is an instance of a natural kind, ..and what is naturally necessary in our world is what must be true in any world of the same natural kind.
Clarification
By 'world' philosophers mean the whole of this universe
Gist of Idea
The whole of our world is a natural kind, so all worlds like it necessarily have the same laws
Source
Brian Ellis (The Philosophy of Nature: new essentialism [2002], Ch.6)
Book Reference
Ellis,Brian: 'The Philosophy of Nature: new essentialism' [Acumen 2002], p.120
A Reaction
This is putting an awful lot of metaphysical weight on the concept of a 'natural kind', so it had better be a secure one. If we accept that natural laws necessarily follow from essences, why shouldn't the whole of our world have an essence, as water does?