Many systems biologists claim that their approach will allow them to overcome the limitations of traditional molecular biology with its allegedly ‘simplistic’ or ‘reductionist’ strategy. They deem this strategy inadequate to cope with the true complexity of living organisms as revealed by large scale experimentation such as the human genome project. I argue that systems biology, in order to be productive, has to provide alternative strategies for reducing the complexity of our representations of living systems. He calls these strategies ‘heuristic’ since they also rely on simplifying assumptions that, when not justifiable, may introduce systematic bias. By using a set of representative case studies he wants to motivate the claim that scientists should not fear a plurality of different approaches, including the ‘traditional’ ones, and instead exploit the potential for mutual correction amongst these alternatives.