Full Idea
If we use geometry and optics to explain the length of shadow cast by a flag-pole, this seems to be reversible, so that the shadow will explain the length of the pole.
Gist of Idea
If laws explain the length of a flagpole's shadow, then the shadow also explains the length of the pole
Source
Stathis Psillos (Causation and Explanation [2002], §8.5)
Book Reference
Psillos,Stathis: 'Causation and Explanation' [Acumen 2002], p.224
A Reaction
A neat example which presumably implies that an explanation must involve temporal statements. The laws of physics are totally reversible in time, and so will not suffice to explain events on their own. Time's arrow becomes an axiom of explanation?
Related Idea
Idea 13061 Flagpoles explain shadows, and not vice versa, because of temporal ordering [Salmon]