Design Principles: Weakest Link

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Elements in a system can be protected by incorporating a weak link. The weak link protects the rest of the system by failing first. Thus, the weakest link is one of the most important elements in the system.

To design a protective, weak link:

  1. identify a failure condition
  2. identify the weakest link in the system for that failure condition
  3. further weaken the weakest link and strengthen the other links as necessary
  4. ensure that the weakest link will only fail under the appropriate, predefined failure conditions

Universal Principles of Design; Lidwell, Holden, Butler

Framework Limitations


The weakest chain link analogy only works in linear systems. Systems are often non-linear and much more difficult to manage. Think “food chain” vs “food web” in an ecology.

Interruptions in a complicated system may have unintended consequences or not be slowed by a “weak link” at all.


Error Handling

It is also often the case that a system needs to be designed to withstand errors or handle errors in a helpful manner while continuing operations


The “blue screen of death” is frustrating because it is a total halt of operations, without helpful feedback about the error. Most users would prefer for the system to withstand and contain the error with feedback.