As sentient beings, humans have the power to choose how they act based on their thoughts. This capability is useful only to the extent that we recognize and correctly understand the relationships between cause and effect.
Models are an effective way to explicitly state our understanding of a system. Models are characterizations of relationships between entities in a system. The purpose of a model is to reveal what actions will yield a desired effect. While the complexity and indeterminate nature of reality suggest limits to any finite model, models are nevertheless powerful tools to increase the reach of our understanding and the intentionality of our actions.