SJC wrote:if your second premise had read "and someone who is eligible to be a British citizen is eligible for a British passport", your argument would have been valid
Logic - "if A implies B and B implies C, then A implies C".
If you are eligible for British citizenship then you are ultimately eligible for a British passport.
I am very familiar with the rules of logic! The problem is that you are saying A implies B but C implies D. Eligibility does not mean that you actually have. There are plenty of things that I am eligible for, but unti I have got them, I can't take the next step. Somebody who is eligible for British citizenship should be able to get a British passport, but it's not guaranteed until they have it in their hand. After all, who is defining that eligiblity? if it's anybody other than those who decide to give you a passport, then that 'eligibility' is not worth a candle, and you'll only find that out when you apply.
Thus, if you are using these as your definitions, someone has to be either a British citizen or be a British passport holder, not just eligible, because neither organisers nor British Orienteering are in a position to make that judgement. (Not that I'm arguing these should be criteria).