Could there ever be another world war?
Is there a possibility of world war III? What would cause it? Who would be in it? Why?
I think there is always that distinct possibility. Politics and humanity are constantly changing and evolving so its hard to say if something will ever happen again or will not but we can make some near future predictions based upon the past.
When we look at the things that caused the previous two world wars we see some common themes like alliance systems, nationalism, rise of dangerous political ideologies like fascism. These were symptoms of a very different world. Today we don't just have history to keep us on the lookout for such things, we also are far more interconnected both technologically but also economically.
Today's world is a global one, and is far more prosperous than at any other time in human history. Despite what you may see on social media, there are less people worldwide in poverty than ever before. The globalization of our economy has produced a lot of wealth but also has bound countries with opposite ideologies together. Think China and the United States, both ideologically apart, but economically dependent. The more economically dependent nations become, the less likely they are going to be willing to fight a war and risk that prosperity. We are incentivized by capitalism to take the high road.
Now there is always the fear of the rogue dictator that doesn't care about money and just wants to conquer the world. This is the sort of fear we have about North Korea or ISIS. These groups driven by ideology, religion, or power are the real wild card that we have spent the better part of the last two decades fighting. Thankfully, these groups are small, and at this point could never attain the military might required to challenge a large nation like the US or China in open combat. They can be a nuisance, they can engage in terrorism, but actually take over a developed nation like France the way Hitler did in WWII, I think not.
In the end the combination of incredible military strength by the biggest countries, economic interdependence, and technological connection of people makes it much harder for complete world wars to break out as they had in the past. In general we know how brutal these wars are and how expensive they are for all parties. That's not to say a nation could not see another Hitler, it would just be much harder for them to turn and fight the major powers of the world today.