the argument from some - Graham for example seems to be if you wear a helmet you must wear full body armour to do all activities or else this decision is inconsitsnet or not well concieved
Mmm.. that's not really my point at all.
I'm suggesting that everyone has a level of acceptable risk/consequence and they mitigate against that as they see fit.
There is always something more you could do to prevent the risk (including just not getting on a bike in the first place!)
So we all have to make a decision about where we stand on that particular sliding scale and take precautions as we see fit.
If a grown adult has considered the risks they face and made an informed decision that they don't need a helmet then fair play to them I say.
Chastising them and calling them names for that decision is daft.
You've just decided to wear one more piece of protective equipment than them. Woo hoo.
Tutting quietly behind you on the scale is someone who thinks your mad for not wearing knee and elbow pads. And tutting behind him is someone who wears a full-face motocross style helmet. And behind him is someone who thinks everyone should have spine protectors. And behind them all is a grumpy old sod sat on the sofa with a cuppa, rolling his eyes at all these silly mountain bikers putting themselves in unnecessary danger.