Date: Sep 17, 1999 2:30 AM
Author: Steve Leibel
Subject: Re: -1 x -1 ?

In article <937516347.13527.0.nnrp-14.c2debf68@news.demon.co.uk>,

"Guillermo Phillips" <Guillermo.Phillips@marsman.demon.co.uk> wrote:

> Hello All,

>

> Here's something I've always wondered (perhaps in my naivety). Why

> should -1 x -1 = 1?

> I appreciate that lots of nice things come from this, but what's the

> fundamental reason for it?

>

Because 1 times anything is anything. That's the essential quality of

one-ness, what mathematicians call a multiplicative identity. 1 does the

same thing for multiplication that 0 does for addition, namely "leave the

other thing unchanged."

If you have the concept of multiplication, then you have the concept of

multiplying a number by a number, and then you must philosophically have

the concept of NOT multiplying a number by a number. What is the result

of NOT multiplying 5 by anything? 5, right? So "multiply by 1" is a

synonym for "don't multiply at all."

You asked a pretty deep question.

Steve L