The question arises when people get confused between a cut and span. These two are opposite concepts, and they make up a continuum, and they define each other.

The question arises when people get confused between a cut and span. These two are opposite concepts, and they make up a continuum, and they define each other. So, it depends on what you understand as "numbering". If it is about counting objects, the word "first object" refers to existence of non-zero number of objects. This shows why the first one can't be called as zero, as zero is not equal to non-zero. If the numbering is about continuous scale such as tape measure, then the graduations can start with zero. But still the first meter refers to one meter, not zero meters. It looks silly when people have their book chapters numbering to begin with zero. They have no clue whether the chapter refers to a span or a cut. Sure, they can call the top surface of their book cover as zero, though. But still they can't number a page as zero. The use of zero index for memory location comes from possible magnetic states of array of bits. Each such state is a kind of a cut, not a span. It's like a graduation on the tape measure, or mile stone on the side of the road. So it can start with zero. So, if you are counting markers or separators, with zero magnitude, you can start at zero. And when you count spans or things of non-zero magnitude, you start at one. If you count apples, start at one. If you count spaces between apples start at zero.