To me, “negative 7” sounds wrong, like someone calling the year 1985 “one thousand, nine hundred eighty-five.” It’s usually “7 below” but also “minus 7.”
Similarly, I definitely prefer currency to use the symbols. I instinctively think of “$50” as money, have to take an (split second) extra mental step to process “50 dollars” that way. This has also made it easy for me to process other currencies that way, since they have a funky symbol.
I dug out my trusty Associated Press Stylebook (note: one word) and Briefing on Media Law and quote from it verbatim.
Then I listened to the NOAA weather report for Chicago. If you’ve never heard a NOAA report, it uses a computer synthesized voice. It reported the temperature as “minus 16 degrees.”
I have also heard respectable mathematicians teach the exact opposite, that is, always to say “minus”. Not sure what the reasoning would be, either way.
Back to the weather, Jack London sometimes, interestingly, refers to “degrees of frost”. For example, -50 F are “eighty-odd degrees of frost”.
I don’t see the problem either. The weatherman is speaking to the general public. They want to use easily understood language. It’s 5 below zero or it’s minus 5.
But that’s the thing. Judging by the thread, apparently even mathematicians and folks who deal with negative numbers don’t seem to care or at least have a consensus.
“Positive” and “negative” indicate descriptions for two kinds of a thing. So a positive attitude and a negative attitude are two kinds of attitude. A positive integer and a negative integer are two kinds of integers.
But “positive 1” and “negative 1” are not two kinds of “1.” They are completely separate numbers. They have certain mathematical relationships with each other, but “-1” is not a type of “(+)1.” So that’s why he doesn’t like “negative 1.”
He also did say, however, that usage does change, so at some point there’s no point in objecting.
I mean, I prefer “minus one” or “one below” for temps, but your dad’s distinction seems pretty arbitrary to me. Positive and negative integers can be seen as two kinds of the same thing. A positive is an integer of what you have. A negative is the same integer of what you owe. So both +$7 and -$7 represent seven dollars. In the first, I have them; in the second I owe them. Both in the same quantity. It perhaps doesn’t work that neatly with temperatures, but there are real-world examples of positive and negative integers that both refer to the same quantity, just on which side of the ledger they are.
That’s looking at numbers like an accountant. Remember that my dad is a mathematician. To him, +7 and -7 aren’t just the same quantity on different sides of a ledger. They are two different numbers that exist independently of each other. To him “-7” is a quantity in and of itself, conceptually separate from “+7”. It’s not just “7” placed in a different bucket.
Similarly, to him, “0” is a number that exists in and of itself, an integer that is neither positive nor negative. It’s not the absence of something. He would always correct me if I equated zero with “none” or “nothing” while doing math.