The Mythical Man-Month

The Mythical Man-Month

In the fifth essay of The Mythical Man-Month, titled The Second-System Effect, Brooks circles back to question he left unanswered in the essay Aristocracy, Democracy and System Design. The question was: If functional specialties are split, what bounds are left to constrain the possibility of a runaway architecture and design? The thought is that is that without the pressure of implementation an architect does not have to consider constraints.

Brooks begins the essay by establishing a context to consider the second-system effect with a section titled, “Interactive discipline for the architect”. All architects work within a set of constraints typically established by project stakeholders. Operating within these constraints requires self-discipline. In order to drive home the point, Brooks uses the analogy of a building architect. When designing a building an architect works against a budget and other constraints, such as a location and local ordinances. Implementation falls to the general contractor and subcontractors. In order to test the design, the architect will ask for estimates from the contractors (analogous to the teams in a software environment). Estimates provide the architect with the feedback needed to test ideas and assumptions and to assure the project’s stakeholders that their build can be completed within the constraints. When estimates come in too high, the architect will need to either alter the design or challenge the estimates.

When an architect challenges an estimate her or she could be seen as leveraging the power hierarchy established by separating functions (see last week’s essay). However the architect needs to recognize that in order to successfully challenge the estimate they need to remember four points.

  1. The contractors (development personnel in software) are responsible for implementation. The architect can only suggest, not dictate, changes in implementation. Force will generate a power imbalance that will generate poor behaviors.
  2. When challenging an estimate be prepared to suggest a means of implementation, but be willing to accept other ways to implement to achieve the same goal. Recognize that if you make a suggestion before being asked that you will establish an anchor bias and may not end up with an optimal solution.
  3. When making suggestions, make them discretely. Quiet leadership is often most effective.
  4. The architect should be prepared to forego credit for the changes generated as estimates and constraints are negotiated. Brooks pointed out that in the end it is not about architect, but rather about the solution.

The first part of the essay established both the context and framework for developing the self-discipline needed to control runaway design. Brooks concludes the essay by exposing the exception he observed. Brooks called this exception the second-system effect. In a nutshell, the second-system effect reflects the observation that a first work is apt to be spare, where as second attempts tend to be over designed as frills and signature embellishments start to creep in. Brooks points out this behavior can often be seen in scenarios in which a favorite function or widget is continually refined even as it becomes obsolete. For example, why are designers spending precious design time on the steering wheel for the Google self-driving car? (It is should be noted that recently the steering wheel was removed from the self-driving car then put back in  . . . with a brake).

How can you avoid the second-system effect? The simplest would be to never hire an architect with only one design job under their belt therefore avoiding the second-system effect. Unfortunately that solution over time is a non-starter. Who would replace the system architects that retire or move to other careers. Other techniques, like ensuring everyone is aware of the effect or stealing an idea from Extreme Programming and paring architects with other more seasoned architects or business analysts, are far more effective and scalable.

Brooks provides the punch line for the essay in the first two paragraphs. A project or organization must establish an environment in which self-discipline and communication exist to reduce the potential for runaway design.

Previous installments of Re-Read Saturday for the The Mythical Man-Month

Introductions and The Tar Pit

The Mythical Man-Month (The Essay)

The Surgical Team

Aristocracy, Democracy and System Design

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