Full Idea
Where theories intersect, laws are usually hard to come by.
Gist of Idea
There are few laws for when one theory meets another
Source
Nancy Cartwright (How the Laws of Physics Lie [1983], 2.3)
Book Reference
Cartwright,Nancy: 'How the Laws of Physics Lie' [OUP 2002], p.51
A Reaction
There are attempts at so-called 'bridge laws', to get from complex theories to simple ones, but her point is well made about theories on the same 'level'.
Related Idea
Idea 16177 I disagree with the covering-law view that there is a law to cover every single case [Cartwright,N]