Composition/Division: In the two overall sides of the argument we have overgeneralizing of black people being criminals/dangerous and all white police officers being racist. Although there are black criminals, there are also many many white criminals and the assumption that all black people mean harm is a dangerous generalization. Same goes for the opposing side, some police officers many abuse their power and let racist tendencies make decisions instead of unbiased reason-- but not all white officers work like this.
Slippery Slope: When the military got involved it suggested that since there was a protest (a mostly peaceful one) it would turn violent. Having such a strong military presence suggested that there shouldn't be protesters because if they allow A to happen (protesting) then B would happen (violence) and there fore A should not be happening.