So my dad calls me today from Erie, Pa., and asks me, "How would you say that the temperature is 14 degrees below zero?" "Well, I would say it's fucking cold, Dad." "No no, would you say it was 'minus 14 degrees' or 'negative 14 degrees'?" My dad believes that people of an older generation say "minus" and younger people tend to say "negative" when referring to the temperature outside. He's afraid that when his generation dies, the proper term will fade away forever and the world will refer to the temperature incorrectly. Please help clear up this generational struggle!
Going by the book, your dad is probably right.
On the one hand, both terms are equally mathematical; algebra isn't the problem here. But temperature is screwy. We pick an arbitrary scale at which water freezes at 32 degrees, and temperatures below zero suddenly have no great meaning. The fact that it's 20 degrees outside doesn't mean that it's twice as warm as when it's 10 degrees. Convert to Celsius and those numbers have entirely different implications, even though you don't feel any colder.
So using "negative" implies a greater integer value, while "minus" is more of a relative thing. In a way, "minus" is less committal--you're still holding out hope that minus 14 degrees isn't quite as cold as it sounds.
Dictionaries and style guides back this up, by the way. Both the AP Stylebook and Merriam-Webster 's list "minus" as more appropriate when talking temps. "Negative" has nothing to do with it.
But the end of your letter hints at the deeper implications here--which is to say, there aren't many. Let's say your old man's fears are realized: His generation dies ... and the proper way to report the weather is lost to history.
Frankly, if it's 14 below, you have bigger things to worry about. Like your face falling off.
The meaning of both is unambiguous. Give it enough time, and dictionaries will start to reflect the change too.
Besides, by the time we reach that point, global warming will ensure temperatures below zero are a thing of the past anyway.