### Single Idea 9419

#### [catalogued under 26. Natural Theory / D. Laws of Nature / 4. Regularities / b. Best system theory]

Full Idea

A contingent generalization is a law of nature if and only if it appears as a theorem (or axiom) in each of the true deductive systems that achieves a best combination of simplicity and strength.

Gist of Idea

A law of nature is a general axiom of the deductive system that is best for simplicity and strength

Source

David Lewis (Counterfactuals [1973], 3.3)

Book Reference

Lewis,David: 'Counterfactuals' [Blackwell 2001], p.73