It isn't the "not knowing" that injures. It is leaving ourselves in a dangerous situation. Children learn to take their hand away from a flame because it hurts. If there was no hurt, you could theoretically leave your hand there and get severe burns without knowing it.

In varying degrees, the screwed-up nervous system can sometimes prevent “realistic” sensations of hot and cold. For example, I might think my (very cold) right foot is very comfortable but, in reality, I am subjecting it to so much heat I could get a burn.

I hope this clarifies what I was trying to say.

Mike