By Richard E Walrath

Definitions, facts, theories, principles and myths.  At some point, you have to know which is which.

Do you know what a theory is?  There’s a popular misconception of what a theory is. A theory is not just an idea about something. A theory is based on empirical observations which have been tested over time. 

Lost Prophets: An Insider’s History of the Modern Economists (1994) by Alfred L. Malabre, p. 220 quotes John Maynard Keynes as saying "When the facts change, I change my mind. What do you do, sir?".  The comment was apparently given in reply to criticism aimed at Keynes for changing his monetary policy position during the Great Depression.

A theory is the best explanation of the facts that exist at that time. 

When It’s no longer even a theory it’s consigned to the dustbin of useless ideas.  It didn’t work.