Quality is Emergent
Why you can't build quality in, but you can build the conditions for it.
One of the most misunderstood aspects of software is that quality is an emergent property of complex systems. Quality appears through the way people, tools, code, decisions, constraints, environments and many other variables interact over time. Which means you can’t reliably predict the system’s quality at any given moment.
And even if you could predict it with some certainty, the people involved add a whole other layer of complication. Each person experiences the systems through their own frame of reference, which is unique to their expectations, knowledge and context. All of this affects their perception of quality.
Do we ignore quality?
A useful starting point is who matters to the success of the software system. For instance, this could be the people who work for the business that commissioned the system, and the people who the system is intended for. We often refer to them as stakeholders. By observing and speaking with them, we can identify the system attributes they care about. Things like reliability, security, accessibility, performance, user experience, the job the system is intended to do and so on. These are the quality attributes that we can work to support.
But we can take this a step further.
By taking the time to study the system and how it behaves, we can begin to identify its operating patterns. Specifically, to look for patterns that enable the creation of quality, the maintenance of quality, and its loss. These patterns can sit anywhere from how teams, technology, processes, culture, and infrastructure interact. 1
When you combine knowledge of your stakeholders, your quality attributes, and operating patterns, you get what I call quality knowledge. This is the shared understanding of what matters, how the system behaves, and where quality is created, maintained, or lost. That is the foundation of Quality Engineering.
How do you build quality in?
Engineering teams can use that quality knowledge to change the system. This can involve influencing how people think through philosophy. Influencing how people behave through frameworks and practices. Or influencing the actions people take, through tools and automation. Each approach nudges the system towards the quality outcomes they want and less of the ones they don’t. 2
What do Quality Engineers do?
A Quality Engineer is someone who uses quality knowledge and enables engineering teams to build those quality attributes in. But this doesn’t have to be someone with a quality background, like a Tester or Software Engineer in Test. Developers, leads, principals, and even distributed groups across a team can play this role. The role is defined by the intent, not the job title. 3
Close
You cannot force an emergent property into existence. But you can influence the environment it emerges from. That is what quality engineering is all about. It’s not bug catching, adding more tests, or promising certainty where none exists.
It is learning how your system behaves, understanding what people value and shaping the conditions that make good outcomes more repeatable.
Because in complex software systems, quality is not something you can build, it is something you cultivate.
Start your journey: If you’re wondering what operating patterns mean for quality, then start with What is Quality Engineering?. Once you’ve got the basics, take a deeper dive into a real-world example with my analysis of the 2024 CrowdStrike outage to see how patterns of quality loss emerge in practice.
Explore the bigger picture: Philosophy, frameworks, tools and nudges aren’t just buzzwords, they shape how we think and work. In Quality Engineering as Philosophy, a Framework, and a Tool, I explore how these pieces fit together and why that matters for building resilient systems. Then, in Nudging and Boosting Complex Systems, I share how subtle interventions can steer systems toward the patterns we want.
Put it into practice: What does a Quality Engineer actually do? And how can teams embed quality into their culture? I unpack the role in What is a Quality Engineer?, and share practical strategies in Three Approaches to Foster a Culture of Quality so you can put these ideas into action.