Lehman and Belady have studied the history of successive…
![“Lehman and Belady have studied the history of successive releases in a large operating system.[6] They find that the total number of modules increases linearly with release number, but that the number of modules affected increases exponentially with release number. All repairs tend to destroy the…” quote by Frederick P. Brooks Jr](https://sms4smile.com/q/i/115/frederick-p-brooks-jr-11230_history_lehman-and-belady-have-studied-the-histo_145780.jpg)
““Lehman and Belady have studied the history of successive releases in a large operating system.[6] They find that the total number of modules increases linearly with release number, but that the number of modules affected increases exponentially with release number. All repairs tend to destroy the structure, to increase the entropy and disorder of the system. Less and less effort is spent on fixing original design flaws; more and more is spent on fixing flaws introduced by earlier fixes. As time passes, the system becomes less and less well-ordered. Sooner or later the fixing ceases to gain any ground. Each forward step is matched by a backward one. Although in principle usable forever, the system has worn out as a base for progress. Furthermore, machines change, configurations change, and user requirements change, so the system is not in fact usable forever. A brand-new, from-the-ground-up redesign is necessary.””
About This Quote
This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation.
Software systems accumulate complexity over time, making incremental fixes counterproductive; eventual redesign is required.
In simple terms: Programs get messier, needing a fresh start.
Key Takeaway
Plan for periodic redesigns.
Themes
software engineering
entropy
maintenance
Mood
analytical
cautious
Type
technical
philosophical
When to use this quote
- large OS updates
- enterprise software
- IT infrastructure
Key Concepts
technical debt
system decay
legacy code
Questions to Reflect On
- How can we mitigate technical debt?
- When is redesign justified?
A Different Perspective
Redesign is costly and disruptive.