Once you’ve defined the problem you’re ready to move to the next step: understand its root cause(s).
Understanding the root causes of a problem help you focalize your thinking around solutions that can truly bring you closer to where you want to be; so, in general, it is a good idea to first make sure you understand precisely your problem before looking for ways to correct it.
For complex problems, it is useful to build a logic tree—a “why” tree in this case— to organize and test your hypotheses. This requires you to have a logical thinking process, and, in particular, you’ll need to think with mutually exclusive and collectively exhaustive (MECE) elements. Building logic trees also requires you to innovate in your thinking, going further than the obvious answers.
A useful tool for building “why” trees and applying MECE thinking is to think in terms of processes. Another useful tool is to use existing frameworks whenever possible.
As with defining problems, you can’t expect to be excellent at diagnosing problems without practicing it extensively. When you do, it is a good idea to enlist others to challenge your thinking.