Full Idea
Pure regularities are not nearly as common as might have been thought, and are usually only to be found in simplified or idealized conditions.
Gist of Idea
Pure regularities are rare, usually only found in idealized conditions
Source
Stephen Mumford (Laws in Nature [2004], 05.3)
Book Reference
Mumford,Stephen: 'Laws in Nature' [Routledge 2006], p.70
A Reaction
[He cites Nancy Cartwright 1999 for this view]