About half of the questions of the mac can be supposed to be about osx (and then I didn't include tags like osx-lion), whereas the tag is meant to be about hardware, this evidences that the mac tag is deadly ambiguous.
When a tag is ambigious the approach is often to get rid of it. So let's suppose that we get rid of mac and see how we approach it then. When doing this it would leave quite some questions with tags that don't make clear that we are talking about Macintosh.
This approach does however conform to the fact that we don't have a pc tag either. But it will require us to first make sure that any of the mac questions that are not about osx get a more specific tag like mac-pro, mac-mini, imac. This however requires the same amount of effort as Oliver's answer...
It looks though that we can automate a part of it, which are those questions tagged osx and variants. If we make sure that these simply can get their mac tag removed then it's just a matter of asking the developers to do something like selectQuestionsThatAreTagged('osx').removeTag('mac') which will cut down the questions we have to go through over time in half.
Renaming the tag from mac to mac-hardware while we are in the process of giving them more specific tags will at least make sure that no new OS questions roll into that tag.
To summarize the whole thing, here is what I think is a good approach:
Figure out whether we can remove the mac tag from all osx questions as well as from variants like osx-lion, this requires to go through (read them, not edit them) a list of 2000+ questions to check that they are not about hardware, otherwise tag these appropriately (giving them mac-hardware if the tag is to be kept).
Ask a developer to do
selectQuestionsThatAreTagged('osx').removeTag('mac')once we are certain that it is safe to disband both tags.Ask a moderator to merge mac into mac-hardware such that no new non-hardware questions are added to it.
Over time, we retag every question from mac-hardware in more specific tags like mac-pro, mac-mini, imac, ... to eventually get rid from the mac-hardware tag. This makes it consistent with the fact that we don't have a pc tag either...
