By the time we get to ADWD, the War of the Five Kings is over, but as the scope of the story pulls up like a camera, more battlefields and conflicts enter our view. Two mirror-image battles are waging with millions of lives promised to be lost: The battle of Winterfell between the Boltons and Stannis' Wildling army and the battle of Meereen on land and sea. Plus the Iron Islanders are taking cities and castles along the west coast while Mace Tyrell's armies are sitting on a barrel of explosives in a standoff with the now-armed church. Oh, and let's not forget (even though the TV series have) the Golden Company and Prince Aegon who have taken Storm's End, the last we heard.
This is a question that applies to the real world much more than fiction: Is human history one of perpetual wars, with brief respites of temporary but unstable peace? Or are we more inclined to live in peace and periods of war are the anomaly? Given that we are living in a stretch of time that has not seen a world war for 70 years, it seems like we are moving in the direction of peace. American people are even more lucky than others as United States has not seen armed conflicts on its soil for 150 years. However, if we pull up the camera to cover a larger scope, the picture changes. Even now we are looking at a state of interminable military involvement. Since 1945, US has been directly involved in the Korean War in the 1950s, the Vietnam War in the 60s to early 70s, the first Gulf War in the early 90s, the second Gulf War in the early 2000s. The frequency is approximately the same as that in Westeros history, if not higher. We cannot go through even one generation with bloodshed, it seems.
In ASOIAF, even when one area (eg, Dorne or Highgarden) is teetering on a vicarious peace, war is raging somewhere else in the world. While we can live in the illusion of peace in our daily lives, we are nevertheless involved in armed conflicts one way or another. For instance, we are all complicit as our tax dollars go into this drone and that bomb. No US president has ever not given orders to kill someone, and therefore our votes are also implicated.
The optimistic Steven Pinker believes that the better angels of our nature are winning in the long run, evidenced in the diminishing proportion of violent deaths over time. I am not in the position to judge whether this hopeful trend holds in the next centuries or whether the recent era is just another blip of peace in our violent history.
Regardless, I think one can hardly deny that our nature is not a blank piece of paper and that violence is a part of it. I'm very reluctant to label it as "worse devils" of our nature. Few would admit that they like violence or enjoy killing, but there must be something deeply irresistible that leads us to warring with each other. It's almost like wars are a home of our spirit. We try to stay away from it and avoid any mention of it, and may even succeed for some years or some distance, but sooner or later we cannot help but return to it. Why? Chris Hedges says, War is a force that gives us meaning. His point is that nothing can bind people's (especially men's) spirit together and fends off the existential loneliness like war can. Sigmund Freud credits the Death Drive, which is as strong as the drive to survive. Whatever it is, I'm not sure it's something that can be easily erased from the depth of humanity, or that it should be.