Of course not, we all operate in uncertainty. We can try to make ethical decisions even while quantified ethics are an unsolved problem.

We don't know how many victims there were of the Nazi atrocities, but I feel pretty confident going by what you could call their qualitative, "labels." In fact, I don't think the true casualty numbers are known for most wars and genocides. Utilitarian calculations are limited to situations with controlled conditions and scientific openness, like when charities try to keep track of their cost effectiveness.

This is definitely a well thought out comment that's worth replying to.

If you're asking if every citizen living in Germany from 1933-1945 did only evil things, the answer is obviously no. If you're asking if every person who was ever in the nazi party was a uniquely evil human being, also no.

I just think moral questions are clearest in the extreme.