--- title: Principle Misunderstandings - Kevlin Henney - NDC... description: Kevlin Henney's NDC Toronto 2026 talk critically examines widely misunderstood software development principles. He argues that DRY (Don't Repeat Yourself) is... canonical: https://daily.dev/posts/principle-misunderstandings---kevlin-henney---ndc-toronto-2026-f9e5a55fe twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Principle Misunderstandings - Kevlin Henney - NDC Toronto 2026 | daily.dev og:description: Kevlin Henney's NDC Toronto 2026 talk critically examines widely misunderstood software development principles. He argues that DRY (Don't Repeat Yourself) is... og:url: https://daily.dev/posts/principle-misunderstandings---kevlin-henney---ndc-toronto-2026-f9e5a55fe og:image: https://api.daily.dev/og/posts/F9e5a55fe.png og:image:alt: Principle Misunderstandings - Kevlin Henney - NDC Toronto 2026 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Principle Misunderstandings - Kevlin Henney - NDC Toronto 2026 **[NDC Conferences](https://daily.dev/sources/ndc)** · 64 min read · 0 upvotes · 0 comments ## Summary Kevlin Henney's NDC Toronto 2026 talk critically examines widely misunderstood software development principles. He argues that DRY (Don't Repeat Yourself) is commonly reduced to 'avoid code duplication' when it actually concerns the duplication of knowledge and intent across an entire system. He distinguishes data hiding (a language-enforced mechanism) from information hiding (a people-and-organizational discipline). He dissects the Single Responsibility Principle, showing that 'responsibility' has been redefined multiple times and that the principle collapses under scrutiny — cohesion and coupling are the deeper, more meaningful concepts. Finally, he revisits Dijkstra's original 'separation of concerns,' revealing it was about managing human attention, not code structure. The overarching message: many things defended as principles are actually preferences or heuristics, and many of these principles are fundamentally about people, not code. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [DRY Is the Most Misunderstood Rule in Programming](https://daily.dev/posts/dry-is-the-most-misunderstood-rule-in-programming-ithr21mpi) · Milan Jovanović · 11 upvotes · 0 comments - [When to repeat yourself](https://daily.dev/posts/when-to-repeat-yourself-c67y3splj) · The Polymathic Engineer · 175 upvotes · 7 comments - [DRY Principle in C\#: Don't Repeat Yourself - A Practical Guide With Real Code Examples](https://daily.dev/posts/dry-principle-in-c-don-t-repeat-yourself---a-practical-guide-with-real-code-examples-8agmhlwu5) · C\# Corner · 6 upvotes · 0 comments - [Back to Coupling and Cohesion](https://daily.dev/posts/back-to-coupling-and-cohesion-mey4bh3qy) · Programming Digest · 2 upvotes · 2 comments - [KISS, DRY, SoC, and YAGNI: The Only 4 Software Principles You Actually Need](https://daily.dev/posts/kiss-dry-soc-and-yagni-the-only-4-software-principles-you-actually-need-vuqtrjfce) · Medium · 1 upvotes · 1 comments --- Tags: [#general-programming](https://daily.dev/tags/general-programming) [View this post on daily.dev](https://daily.dev/posts/principle-misunderstandings---kevlin-henney---ndc-toronto-2026-f9e5a55fe) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Principle Misunderstandings - Kevlin Henney - NDC Toronto 2026","url":"https://daily.dev/posts/principle-misunderstandings---kevlin-henney---ndc-toronto-2026-f9e5a55fe","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/principle-misunderstandings---kevlin-henney---ndc-toronto-2026-f9e5a55fe"},"datePublished":"2026-08-04T11:28:31.957Z","dateModified":"2026-08-04T13:15:46.385Z","description":"Kevlin Henney's NDC Toronto 2026 talk critically examines widely misunderstood software development principles. 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