Date: Thursday, 7 December 2000
From: Peter Meyer
Subject: Re: Millennium Article

Dear Mr Fox,

You wrote:

>I have a question about your calendar page. Why can't the years be
>numbered like this:
> ....... -3, -2, -1, 1, 2, 3, 4 ........ Even if we replace
>the BC years with negative numbers, I still don't understand why there
>needs to be a year zero.

In the Gregorian Calendar the years are already numbered as above, the difference between "-2" and "2 BC" being merely notational, not a matter of numbering.

However, it would be misleading to represent the year 2 BC by "-2", etc., because the generally understood system of integers is ... -1, 0, 1 ... not ... -1, 1 ...  In the latter sequence, 0 is missing, so a year would also be missing if ... -2, -1, 1, 2 ... were used as a model for the sequence of years.

There is the necessity for an integer 0 in the system of integers, because that's how the integers are, but, as you say, there is no need (necessity) for a year zero. This is because there is no necessity for the integers to be used as a model for the sequence of years. On the other hand, there is no necessity for the integers not to be used as a model. As I say in the article, we (you, I and others) have a choice about which model to use, i.e. which system of year-numbering to use, and we can choose a model on the basis of one or other of adherence-to-tradition, rationality, aesthetics, convenience, etc., as we prefer.

Peter Meyer