== Why weren't Nazi right? == 

 In my school a girl asked the teacher why the Nazis were not right in their attempt to exterminate other peoples and why other peoples and races should be at all. The teacher thought a while and answered that other peoples are needed for diversity and without them it would be tedious. I feel the answer did not satisfy that girl because she can argue that uniformity is better than diversity or that it would not be tedious for her to observe other races extinguished. Is there any respectable criticism of Nazi ideology satisfactory in modern world?