In the simplest way possible, if we have both Agreement and Certainty on a problem, then an agile approach is probably applicable, but not necessary. As we move away from that bottom left quadrant of the model, the usefulness of an agile approach increases since agile methods promote learning, careful search, feedback mechanisms, multi-disciplinary work, etc. The top right quadrant, "Chaos" is, like the bottom left, a case of possibly useful, but not a guarantee of any success. So agile methods seem most suited for a broad sweep of the diagram starting from the upper left and going down to the bottom right. Like so: