Raymond Chen writes: The great thing about priorities is that you can always go one higher:

Over the past few years, I’ve seen a shift in the labelling of priorities in planning documents. A new priority has been introduced: Priority Zero. Nobody has explained to me what Priority 0 means, but I assume somebody invented it to emphasize that the feature is even more critical than priority 1. Mind you, I’m not sure what could be more important to a project than ‘If we don’t do this, we’re all fired.’ Maybe ‘If we don’t do this, the earth will explode.’

As you might expect, priority inflation has a trickle-down effect. People whose features had been assigned priority 1 said, ‘Hey, how come my feature isn’t priority 0? It’s just as critical as that other guy’s feature.’ Soon, everything that was priority 1 got reclassified as priority 0. Nature abhors a vacuum, so all the priority 2 items got reclassified as priority 1, and the priority 3 items got reclassified as priority 2.

This was common towards the end of my days at ISS. We were bombarded with “level zero” issues that had to be fixed now, and there was plainly nothing more important. Except the ever-growing list of other “level zero” issues. Luckily here at Nokia we have a pretty clear P1-P3 system that doesn’t show any signs of inflation.