Suppose that Bob bumps into Frank, and Frank takes offense. The argument escalates from harsh language to yelling to threats to pushing. Neither man makes any effort to placate the other or depart. Ultimately, a serious fistfight ensues. At that point, does either man have the right to defend himself using deadly force? If so, doesn't that mean that a person might use that method to murder another under the guise of self-defense? Basically, does instigating or escalating a verbal or physical altercation with another person preclude claims of self-defense?