--- title: "Meaning & Key Takeaway of: What [software] must not do is not the…" description: "\"What [software] must not do is not the inverse of what it must do. .\" — Nancy Leveson" image: "https://sms4smile.com/quotes/i/cf5/nancy-leveson-56176_inverse_what-software-must-not-do-is-not-the-inv_1537245.jpg" --- # What \[software\] must not do is not the inverse of what it… ![“What [software] must not do is not the inverse of what it must do. .” quote by Nancy Leveson](https://sms4smile.com/quotes/i/cf5/nancy-leveson-56176_inverse_what-software-must-not-do-is-not-the-inv_1537245.jpg) [Download](https://sms4smile.com/quotes/i/cf5/nancy-leveson-56176_inverse_what-software-must-not-do-is-not-the-inv_1537245.jpg) [Open image](https://sms4smile.com/quotes/i/cf5/nancy-leveson-56176_inverse_what-software-must-not-do-is-not-the-inv_1537245.jpg) > “What \[software\] must not do is not the inverse of what it must do. .” [Nancy Leveson](https://sms4smile.com/quotes/author/nancy-leveson/) ## About This Quote This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation. Software should focus on achieving its intended functions, not merely avoiding errors; the opposite goal is insufficient. **In simple terms:** Software must do what it should, not just avoid mistakes. Key Takeaway Design systems that fulfill core purposes robustly. Themes engineering software safety design Mood analytical pragmatic Type technical instructional When to use this quote - critical infrastructure - medical devices - autonomous vehicles Key Concepts goal‑oriented design failure prevention system integrity Questions to Reflect On - What primary functions should the software prioritize? - How can we test for both success and failure modes? A Different Perspective Avoiding errors alone doesn’t guarantee safety. ★ ★ ★ ★ ★ No ratings yet [Programming](https://sms4smile.com/quotes/about/programming/) [Software](https://sms4smile.com/quotes/about/software/) [Technology](https://sms4smile.com/quotes/about/technology/) ## Related quotes > [Free software is part of a broader phenomenon, which is a shift toward recognizing the value of shared work. Historically, shared stuff had a…](https://sms4smile.com/quotes/mark-shuttleworth/free-software-is-part-of-a-broader-phenomenon-which-is-a-shift-toward/) [Mark Shuttleworth](https://sms4smile.com/quotes/author/mark-shuttleworth/) > [... programming requires more concentration than other activities. 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