The problem must be described as logically as possible, and presented as reality. The remainder of the proposal must then build upon this foundation. If your foundation is weak or illogical, then the rest of your proposal will be weak, illogical and will fail to convince the decisionmaker to fund your proposal. Let's take a moment to look at how most people try to solve problems. Problems are, at best, disruptions in our daily routines.
Problems are annoyances.
Most human beings don't want to address or solve problems. We just want them to go away. But real problems don't go away. If anything, they get worse. Let's go back to our headache example.