AI is not a "Junior Engineer"
It's often said that tools like ChatGPT, Claude, or Co-Pilot are like having a Junior Engineer, or, if you ask Mark Zuckerberg, even a Mid-Level Engineer at your fingertips.
I think the comparison sells junior engineers a bit short, though. AI can generate code at an astonishing speed, I'm not going to argue with that, but writing code was never the whole job of a junior engineer, or of any engineer at any level really.
Senior engineers are valued for the experience and judgement they bring to a problem, and if that's true at one end of the scale it seems odd to pretend it isn't at the other. Juniors bring something an AI doesn't, a fresh pair of eyes and a curiosity not yet filtered through years of "that's just how we do it here". A beginner asking an awkward question about something the rest of us stopped noticing long ago can often be where the better idea starts.
Seasoned engineers, for better or worse, can get set in their ways. Juniors tend to turn up keen to learn and with an enthusiasm that is hard not to catch, they'll try things and take a risk on an idea that might not work. Which is exactly what a team settled into its habits needs now and then. Some of the most creative engineers I've had the fortune of working with had only a few years of experience, and it was that willingness to have a go at a problem head-on that made them such strong contributors.
Of course, enthusiasm without experience doesn't always land where you'd want it to, and a junior left to it can take the long way round - that's why the pairing works as well as it does. The senior helps the junior sharpen their instincts and points all that energy somewhere useful. The junior in turn reminds the senior why they got into this in the first place, which is surprisingly easy to forget.
Software engineering was never really about how many lines of code you write - or indeed generate. It's about solving problems well, and the best solutions I've seen come from teams where experience and fresh eyes rub along together. So if someone tells you an AI can replace a junior engineer, I'd say it tells you more about what they think a junior does all day than it does about the AI.