Negative Thoughts

Today we observed a math teacher in action. As a writing instructor, we find math satisfying. Something about the fact that one can arrive at an actual, unambiguous solution. We don't get enough of that in our everyday encounters with writing students. Sure, we can point out when someone goofs up a subject-verb agreement--and we do! Gleefully! But so much of the other content of writing classes is subjective. We can't say that someone is wrong when they choose a boring topic for a personal narrative essay: For all we know, this person just has an unbelievably boring life, a life of deadening routine, a life not worth living! It's hardly the kind of thing that lends itself to a clear-cut declaration of right-and-wrong, though. Math, though. Rules is rules! A + B = B + A! Any number divided by itself is equal to one! A negative times a negative equals a positive! Frankly, we've never understood that last one. It seems counter-intuitive: Two wrongs making a right, somehow. Except, not. We kind of figured out an analogy once: Imagine you borrow money from someone, and you're supposed to pay them back $10 a week. We can think of that $10 you're paying as -10. So, after one week, you're down $10 (1 x -10); after two weeks, you're down $20 (2 x -10). This represents the idea of a negative (the money) multiplied by a positive (the number of weeks) equaling a negative. On the other hand, if you go to pay the $10 (-10), but your creditor says, "Oh, don't worry about paying me this week," it's as if you've gained ten dollars. If this happens two weeks in a row, you've gained $20. So, the negative amount of money multiplied (in a sense) by two "negative" weeks leaves one with money in the bank. Makes sense to us. Hey, scoff if you must, but the next time you explain to someone why a negative times a negative equals a positive, you'll know whom to thank! (That would be the Solipsist.)