Basic, applied, operational, and human activity research systems represent an array of inquiry methodologies. Techniques or methods within each methodology exhibit similar functions, although purposes and results of each inquiry process differ. Appreciation and possible use of the entire inquiry process focuses attention on scale questions within a hierarchy, and encourages use of all methodologies to enhance resolution of diverse situations. Systems inquiry recognizes the need for weed scientists and agriculturists to participate in activities ranging between reductionist science and human action research.