Violence is a bad strategy for overcoming oppression because oppressors usually have the biggest weapons and will win in the end.

Violence is usually a bad strategy for overcoming oppression because those with the most powerful weapons are the one's who usually prevail. The violence that Hamas brought against Israel was met by a far more powerful response from Israel killing many times more people.

There are better strategies. New inventions and economic conditions can disrupt established orders and bring big changes.

The gradual change that the gay liberation movement and feminism has brought in American culture, over the past few decades, is another example. These things are sometimes thought of as subversive ways to gradually erode and change an existing order.