... and Project Management

Projects consist of related individual tasks, performed by people as actors. Without the understanding of projects as systems, our abilities to manage them and influence their outcomes will be unnecessarily limited. 

Of course, not everybody agrees that their being systems is a key characteristics of projects. Traditional project management theories consider functional aspects and processes as the key elements to manage projects. However, systems are complex, with causal relationships less clear, issues and issue management based on their structuring into sub-components of technical, business and social networks. 

... and Complexity

Systems are the condition of complexity.