Full Idea
Given some general theory specifying the fundamental causal powers and thereby laying down the general lineaments of a world, the necessity of certain effects can be inferred. They will be 'hypothetically necessary' (given those powers).
Gist of Idea
Necessary effects will follow from some general theory specifying powers and structure of a world
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 1.III.B)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.15
A Reaction
This is a pretty good statement of the core idea of necessity at the heart of scientific essentialism. Are we to call this 'natural' necessity or 'metaphysical' necessity? Presumably it is 'relative' necessity. Big implications for induction!