Hammer....

 

In 1868, a London periodical, Once a Week, contained this observation: "Give a boy a hammer and chisel; show him how to use them; at once he begins to hack the doorposts, to take off the corners of shutter and window frames, until you teach him a better use for them, and how to keep his activity within bounds."

In his 2003 book, Of Paradise and Power, historian Robert Kagan suggested a corollary to the law: "When you don't have a hammer, you don't want anything to look like a nail."

According to Kagan, the corollary explains the difference in views on the use of military force the United States and Europe have held since the end of World War II.

Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values.

People display this bias when they select information that supports their views, ignoring contrary information, or when they interpret ambiguous evidence as supporting their existing attitudes. The effect is strongest for desired outcomes, for emotionally charged issues, and for deeply entrenched beliefs.