Full Idea
It is important for the nature of virtue that it have a corresponding vice (or two, in the doctrine of the mean). Claustrophobia is not a vice not only because it is involuntary, but also because there is no corresponding virtue.
Gist of Idea
A virtue must always have a corresponding vice
Source
Linda Trinkaus Zagzebski (Virtues of the Mind [1996], II 2.3)
Book Reference
Zagzebski,Linda: 'Virtues of the Mind' [CUP 1996], p.105
A Reaction
Presumably attaining a virtue is an achievement, so we would expect a label for failure in the same field of endeavour. The failure is not purely negative, because bad things ensue if the virtue is not present.