In reply to UKC Articles:
"A similar 'discomfort zone' is required. Unfortunately 'safe' and it's inverse, 'risk', are both relative concepts... It doesn't take long to find out if you 'see' the risk in the same way as your partner. A belay made from a sling thrown over a pile of stones doesn't fill me with confidence..."
It might be just semantics, but there seems to be an important misunderstanding here. 'Safe' and 'risk' are not really the inverse of each other. The opposite of 'safe' is 'unsafe' or 'dangerous', whereas the opposite of 'risk' is 'caution'.
A safe climber knows how to belay, place gear, set up a stance, etc. A safe climber might however decide to do a risky climb with poor gear and belays. That doesn't make them an unsafe or dangerous climber. The route may well be unsafe or dangerous but that doesn't mean the climber is - they're just taking a risk.
On the other hand, you could have a cautious climber who only does well protected routes but who is fundamentally unsafe because he doesnj't know what he's doing. A sling over a pile of stones is clearly unsafe - unless it's the best that's available. If a climber sets up a dodgy belay when it's possible to set up a good belay, they're being unsafe rather than taking a risk.
I would venture that safety is not really a relative term. There are a few practices which some people will view as acceptable whilst others will consider to be unsafe, but that's down to technical points. For the vast majority of practices, it's fairly clear what is and isn't safe. Risk, on the other hand, is a relative term - relative to the climber's ability, experience and, indeed, appetite for risk.