> Start with mice/rats. Move up to rabbits/pigs/dogs, then on to monkeys.
Why not move on to humans afterward? If it's okay to perform unethical experiments as a means to an end, then why not perform them on humans for the maximum benefit? Unit 731's experiments provided agreeably valuable evidence, demonstrating the value in human experimentation; and it's hotly debated that many tests on animals are applicable to humans to begin with, demonstrating the overstated value of animal experimentation. So if it's true that knowledge trumps morality, we're not taking advantage of that fact.