In the current season, there is a group that is devoted to getting a scientist, Eugene, to Washington D.C. as Eugene is supposed to be the one who understands what happened, and how to fix it. They meet up with Glenn on the road and now are at Terminus with the rest of the group at the end of Season 4.
The original group did wonder why, though, as others have mentioned and that's why they went to the Center for Disease Control in Atlanta in the first season. The scientist there explains that they still aren't sure if it's a virus, bacteria or whatever else it might be, and that scientists in France had been the last ones working on understanding it and finding a cure before communications fell apart (or they all died).
They also learned at the CDC that every survivor is infected with whatever it is that makes them Walkers after they die, so that's when they learned they need to kill the brains of the Walkers when they are attacked.
Some of that took place a couple of seasons back when the group visited the CDC and talked to a doctor holed up there. I don't recall the exact details but you could rewatch the episode.
I don't think there is a "why" answer until they find out HOW it happened.
Its Episode 5 of season 1 called Wildfire. You might be able to watch it on Netflix or Hulu.
In all seriousness, what could the characters we know do about it? They're not doctors, scientists or politicians. They're ordinary people trying to survive one day at a time. While they would probably like to understand what happened and change it, if the doctors at the CDC couldn't do the job, Daryl certainly isn't going to be able to figure it out.
I think their main concern right now is staying alive. Walkers everywhere. As to the why, I really don't know what happened in the beginning. I just started watching it at the end of season 3..
Both answers are right. They are preoccupied and its only a show. I feel like if they focused on finding a way to fix it instead of slugging around from farm house to prison to scarry Terminus. Then maybe they would have found a way already.
You try asking that when every second you worry about a zombie eating you.
They did question it in season 1 with the CDC and touched upon with Abraham, Rosita and Eugene
True bro but its only a show.
There too preoccapide with booty
For me that is a big problem. Where's the explanation or even search for an explanation for what has happened to the world?
