I argue that video games make people on the whole, slightly more prone to violence or accepting of violence. I don't think, and I don't think anyone does, that games alone would make a non-violent person violent, but I argue that they make society more accepting of violence. As a result of making people more accepting of violence, an increase in violence from particular individuals might result.
I also argue that games like call of duty and other violent games encourage bigotry, violence and violent responses to world issues, eg the death penalty and criminal justice, military intervention and war.
I don't think games like this should be banned at all, but I do think they have this effect. Its only bad because we dont have other societal structures in place to make people wise enough to not be strongly influenced by these games. This debate however is about whether or not they make one more violent, which I argue they do-even though only marginally.