Science is supposed to be so accurate, so true.
Science is a means of gaining knowledge and understanding about the world.
It proceeds by putting forward theories that best fit known facts or observations. The theory of evolution is simply the theory that best fits what is currently known about the development of species. Eugenics was a movement based on the theory that if you could, by selective breeding, produce faster, stronger or whatever, animals then it should be possible for humans too. You are using the word 'science' here in the sense of someone who just wants to take pot shots at some imagined monolithic entity. If you knew anything about science and scientists you would know that such a monolith doesn't exist.