All Systems Engineering is Model-based

By David Long and Zane Scott

The late Speaker of the United States House of Representatives, Thomas P. (Tip) O’Neill, famously said “all politics is local.” In that phrase he called to the surface a characteristic of politics that was often overlooked but always true. In the same way, we say here that all systems engineering is “model-based”.

How can this be? Isn’t systems engineering divided into camps? Isn’t “document-centric” engineering over and against model-based systems engineering?

But just as the Speaker’s observation was true even as it ran counter to conventional wisdom that divided politics into local and national issues, it is equally true that all systems engineering is model-based.

It is true because it is literally impossible to think systemically without using a mental model. When we take a systems view or begin to conceive of a systemic solution to our particular problems, we must create a mental model which often means building out from existing models that are already there.

Such models are created whether we are aware of them at a conscious level or not. It is simply part of the mechanism with which we think.

This means that all of systems engineering is truly based in a model or models. The question is not whether we use models but how we manage them. Peter Senge says that the existence of these models can work for or against us, depending on how we manage them. Outdated models that have grown rigid over time can block the acceptance of new ideas. New, well-managed models can facilitate new ideas. Senge devotes a whole section of his book The Fifth Discipline to the importance and role of managing these models. He sees this as critical to the whole notion of learning organizations saying, “. . . the discipline of managing mental models – surfacing, testing, and improving our internal pictures of how the world works – promises to be a major breakthrough for building learning organizations.” The Fifth Discipline, Peter M. Senge, Doubleday (1990, 2006) (p. 163)

This is equally true in the world of systems engineering. Models permeate all of our engineering efforts. The point of leverage is gained when we decide to surface the models and make them overt and intentional. Just as the key for Senge’s learning organizations lies in the “surfacing, testing, and improving our internal pictures of how the world works,” the key to successful systems engineering is “surfacing, testing, and improving” our internal models of the context and solutions for our problems. The models already exist – the issue is not whether to use models but how we see, share, and work on them.

All this means that “converting” to model-based systems engineering is not the daunting step we often portray it to be. We are already converted. We don’t need to change our fundamental thought processes. We need to change the ways we act on them.

The choice is not whether or not to use models. The choice is to use them in a way that allows us to share them so that we can get team and stakeholder alignment around the nature of our problems and their solutions. The choice is to use models in a way that allows us to collaborate in improving and testing them. The choice around models is not whether but how to use them. To paraphrase Senge, it is the discipline of managing system models – surfacing, testing, and improving our internal pictures of how they work – that promises to be a major breakthrough for systems organizations.

Leave a Reply