Equifinality is a great $10 dollar word; however, I really believe the underlying concept is very important for everyone in the 21st century. The term was coined by Ludwig von Bertalanffy, the founder of General Systems Theory, a biological precursor to modern chaos, complexity, and systems theories.
Equifinality is the principle that many different causes, independently, can lead to an identical outcome. A more precise definition might be that within a non-closed system, different initial states can lead to the same end state.
Several possible causes —–> A single effect
The problem: just because one knows the result, due to equifinality, one cannot automatically determine the cause! This makes preventing an undesirable outcome very hard without more data.
The next time you work to solve a big problem, consider the possibility that different causes could produce virtually the same effect AND that a remedy for one cause may not have any impact the other potential causes. Save yourself time and money and make sure that your solution is for the right problem.