Why Good Engineering Requires Explicit, Checkable Reasoning Behind Decisions

A software engineering essay argues that true engineering practice differs from craft by making its governing logic explicit and verifiable by others. The author contends that valid system decomposition must attribute structure to specific drivers of forced change, recorded as an artifact others can examine and challenge. Drawing on examples from type inference systems like Hindley-Milner and tools like Nix, the piece highlights how principled refusal — returning no answer rather than a wrong one — is a hallmark of rigorous engineering disciplines. The author applies this standard to architecture, testing, and design, ruling out practices such as grouping code by similarity, writing tests purely for coverage, or drawing module boundaries whose rationale exists only in someone's head. Several concrete tools and methods are cited as real-world examples where refusal-shaped design decisions emerged independently, suggesting the pattern has structural rather than coincidental origins.