Ethics

There are a few famous patients that have advanced medical understanding, particularly in neuroscience, where it's difficult to do methodical analysis without doing damage (see: Henry Molaison, Kent Cochrane -- I read about these in The Power of Habit, which was interesting, if not entirely useful). These patients are patients, rather than just test subjects, because they were victims in accidents where they suffered some sort of brain trauma, and seeing what was damaged, and how it impaired their cognitive capacity, led to insight into how the brain works.

In the past, some of these kinds of advancements have been wrought from straight up Nazi shit, where people would just experiment on other people without their consent. That these atrocities advanced medicine is indisputable. That they're wholly unethical is also indisputable. But what if someone of sound mind volunteered? Could you knowingly do irreparable damage to another person for research to the benefit of all mankind? Chip away at their brain matter, until they couldn't give you any more information?

Rationally, it seems like a no-brainer (lol).