Maslow's Hammer is a cognitive bias caused by an over-reliance on a single, familiar tool. In his own words, "If the only tool you have is a hammer, it is tempting to treat everything as if it were a nail."

To become a better problem solver, you must add a few more tools to the tool belt. Once this tool belt becomes too cumbersome to mule around, you must then invest in a toolbox and fill it.

This doesn't mean you shouldn't specialize in the use of any one give tool. There are, after all, great advantages in becoming the best in the world at a very specific trade. However, it does mean you should gain a working knowledge of many different tools.