In the 10+ years, I’ve spent in software development, I’ve formulated a law of debugging: “The perplexity of a software bug and the simplicity of its probable cause are positively correlated”. Put simply, the more confounding and “impossible” a bug appears to be, the likelier it is that the underlying reason for the bug is not some nightmare compiler edge-case or hardware problem, but rather something that’s actually quite simple. Below are two cases that demonstrate the law in action.

Case #1: Python

My go-to example for this used to be an error in a Python project that took almost an entire day to resolve. Below is a (highly simplified) representation of the code in question: