Someone I knew at university, who prefers starting at 0 (for mathematical, rather than computational, reasons) made the following argument/proposal.
"First" is an abbreviated form of "foremost". So if you start counting at 0, "first" corresponds to index 0. There's no real clash here yet; "first" and "one" are entirely separate terms.
"Second" is from Latin "secundus" meaning "following"; the second thing follows the first. So "second" corresponds to index 1. Again, no clash yet; "second" and "two" are basically unrelated.
"Third", though, actually derives from "three". So "third" has to correspond to index 3.
This leaves a gap, which might perhaps be filled by a new word "twifth", corresponding to index 2.
So now we have the cardinal numbers: zero, one, two, three. And the corresponding ordinals: first, second, twifth, third.
"First" is an abbreviated form of "foremost". So if you start counting at 0, "first" corresponds to index 0. There's no real clash here yet; "first" and "one" are entirely separate terms.
"Second" is from Latin "secundus" meaning "following"; the second thing follows the first. So "second" corresponds to index 1. Again, no clash yet; "second" and "two" are basically unrelated.
"Third", though, actually derives from "three". So "third" has to correspond to index 3.
This leaves a gap, which might perhaps be filled by a new word "twifth", corresponding to index 2.
So now we have the cardinal numbers: zero, one, two, three. And the corresponding ordinals: first, second, twifth, third.