So, there's a white cannibal and he has two potential victims (both currently alive) - a white guy and a black guy (there's no discernible difference between the two (build, etc) aside from skin colour..
Two simple scenario's:
1. the cannibal eats the black guy and lets the white guy live
2. the cannibal eats the white guy and lets the black guy live
In which scenario is the cannibal a racist?