A junior asked me how I knew the code was wrong. I couldn't answer him.

A senior developer reflects on the difficulty of teaching 'engineering intuition' to junior staff in the age of AI. During a pair programming session, the author instinctively identified a flaw in AI-generated code, yet struggled to explain the reasoning behind the decision. The author argues that this 'flinch'—the ability to spot subtle bugs—is not a set of rules, but a form of judgment forged through past failures and production outages. The article warns that by automating the coding process, the industry risks bypassing the 'forge' where junior developers traditionally gain this critical experience. To address this, the author suggests shifting the focus from simply writing code to actively trying to break it, recommending that teams institutionalize skepticism by separating the roles of code author and code skeptic to help juniors develop their own professional judgment in safe, controlled environments.