An excessive dependence upon a specific tool to perform all sorts of functions. The golden hammer principle states that given a specific tool to use, all of the world looks like an appropriate place to use that tool. For example, a small child that is given a hammer may regard everything around him or her as a nail.

The golden hammer is also known as Maslow's Hammer or the Law of the Instrument. It was first voiced by Abraham Kaplan in 1964 and then widely disseminated in Abraham Maslow's book "The Psychology of Science" in 1966. The idea has also been attributed to Mark Twain, despite the lack of evidence to that effect. In business, it refers to an overdependence on a tried and true strategy or instrument, when another approach may be more suitable.