It has been said that something as small as a flutter of an insect wing can cause a typhoon halfway around the world. A cause is regularly followed by its effect. This idea is at the core of regularity theories of causation. The Cause and Effect Theory and Regularity Theory can be found in Hume (1739), the Theory was updated by Mill (1843) who believes that the relevant regularities are laws of nature.

Every action has a reaction, and every cause has an effect.