Full Idea
If two events are related as cause and effect, there is a strict law under which they may be subsumed.
Clarification
'Strict laws' have no 'ceteris paribus' (all things being equal) clause
Gist of Idea
Cause and effect relations between events must follow strict laws
Source
Donald Davidson (Davidson on himself [1994], p.231)
Book Reference
'A Companion to the Philosophy of Mind', ed/tr. Guttenplan,Samuel [Blackwell 1995], p.231
A Reaction
Davidson admits that this is open to challenge (though Hume and Kant supported it). It does seem to be central to our understanding of nature.