Umm, I'm young, but even I know several of these. The main protest behind a lot of these seems to be war, and it's ultimate futility, and the losses it brings. Certainly "War" and "Where Have All the Flowers Gone" have that tone. I'm not familiar enough even with "Blowin' in the Wind" to say - besides, I did't live through it, and I'm sure others are better qualified to answer.

--J