Earlier, I was watching a lecture on YouTube from the series "Justice: What's The Right Thing To Do?", by a man who I assume is a professor of political or ethical philosophy at Harvard. He begins the lecture by presenting a well-known moral dilemma:
You're the driver of a runaway trolley that is about to kill 5 workers on the track. If you pull a lever, the trolley will redirect to a second track, where only one worker is standing and would just as surely be killed. Do you pull the lever?
In a second scenario, you're on a bridge overlooking an empty runaway trolley that is about to kill 5 people standing on the track. There's a man next to you leaning over the railing, and he's just large enough to derail the train (and be killed in the process). Are you willing to push him over to save the 5?
The vast majority of people answer "yes" to the first and "no" to the second. It also generally takes a lot of reflection to give a cogent answer as to how the different answers can be reconciled. In the video, the audience struggles to reason through the arguments.
The lecturer uses this and other examples to illustrate how complicated moral reasoning can be, and describes why it's so important to not take the "skeptical stance," i.e. throw your hands up and declare the whole set of questions unanswerable. But in stressing the importance of carefully examining the various moral arguments that can be applied, I think he's doing a disservice to his audience: he's artificially magnifying the variance in people's tendencies.
What do I mean? Well, in his trolley car questions, there's an implicit assumption: "what do you choose" is assumed by the audience to be roughly equivalent to "what is the right choice?" He knows that the vast majority of his audience is likely not sociopathic, so that even if two people disagree on their actions, the difference is very unlikely to be caused by one person arguing that more death (or more generally, more harm) is the desired outcome.
So what? Well, if the goal is to debate philosophy from an ivory tower, this is a fine way to do it. If one is simply seeking to improve the condition of the world, however, there are much easier ways to go about it. Namely, notice that the vast majority of problems we face are not caused by differing assumptions on right and wrong; far more often, they stem from our inability to live in accordance with those beliefs.
When examining the causes of the Holocaust, it seems much more relevant to ask about the circumstances under which normal people (e.g., the vast majority of the Nazi army) can be induced to commit atrocities against their natural better judgement than to debate the subtleties of the argument for eugenics.
There are of course legitimate moral disagreements (e.g. abortion) that are relevant to us today, but we can be easily tricked into spending a disproportionate amount of time debating them and forgetting about the fact that we're doing oh-so-badly acting on millions of things we already agree on. The day humanity's greatest challenges stem from the difficulty of choosing between two arguably correct choices will be glorious, indeed.