Well, yes. But scientists need to have optimism that their experiments will lead somewhere, entrepeneurs have to be optimistic about there projects (and I'm optimistic that this remark will not get me kicked off this site).  Without optimism great projects would not be undertaken.

Isn't  the 20th century's apparent low death toll from homicide and war just a matter of percentages? The absolute number of deaths from these things is much greater in the 20th century. I think the absolute number matters too.

I believe that David Hume said as much a few hundred years ago.

I haven't made my way through your article yet, though I hope to. But I was a little surprised when you discussed how correlation does not prove causation that you did not mention David Hume who basically says, at least in my reading of him, that no matter how many times one observes lightning and thunder you can not say with absolute certainty that lightning causes thunder.