The explanation states that a vicious cycle is a negative feedback loop while a virtuous cycle is a positive one. Actually, both are positive feedback loops, i.e. self-reinforcing ones. Vicious means that the results are negative, virtuous that the results are positive.
From the linked wikipedia page: The terms virtuous circle and vicious circle refer to complex chains of events which reinforce themselves through a feedback loop. A virtuous circle has favorable results, while a vicious circle has detrimental results. [...] Both circles are complexes of events with no tendency towards equilibrium (at least in the short run). Both systems of events have feedback loops in which each iteration of the cycle reinforces the previous one (positive feedback). 188.8.131.52 23:55, 10 October 2014 (UTC)