This paper discusses several important concepts in cybernetics, including holism, transformation, variety, feedback, control, autopoiesis, and nearly decomposable systems. The paper then examines and critiques three systems methodologies that are based on these concepts, and identifies their strengths and weaknesses. The approaches include Forrester's System Dynamics, Checkland's Soft Systems Methodology, and Beer's Viable Systems Model. The last section of the paper discusses using multiple methodologies to understand a complex system, each of which has different capabilities and strengths to support analysis.