Violence is, with few exceptions a bad thing. Among the exceptions below. There is physical violence, psychological violence, domestic violence, bullying, violence on the Internet, violence at work in Nature and state violence. And perhaps even more species.
The essence of violence is mostly to limit the scope and freedoms of other people or groups. In this regard, violence is always something negative. With the force of nature there is a certain ambivalence, because this type force can be met and energy-bringing, for example in wind turbines, geothermal energy, tidal power plants, hydroelectric plants and so on. Negative is Nature then rightly assessed, if it is, for example, large storms, hurricanes, earthquakes and the like, that also forms of violence that limit or destroy life can.
State violence is also to assess ambivalent. In dictatorships it has already described above proportions are by freedoms and rights of persons restricted or eliminated. In democracies, however, the state power is the guarantee that all people are the same rights granted and maintained. In this sense, violence is something positive.