Cormac McCarthy, when talking about the world, seems to always emphasize that it is nothing but a shell of what the world once was. There are small reminders that make the father and the son see glimpses into the old world. It's bleak and it's very foreign. A quote that describes the world beautifully is on page 88-89:
"The world shrinking down about a raw core of parsible entities. The names of things slowly following those things into oblivion. Colors. The names of birds. Things to eat. Finally the names of things one believed to be true. More fragile than he thought. How much was gone already? The sacred idiom shorn of its referents and so of its reality."
Basically to summarize this passage, things that people concerned themselves with in the old world are dying or already don't exist. Things that used to be important don't matter. What was once an idiom, is now just a combination of fragmented words with barely any meaning. It's a good insight into how the father sees everything because he's the character who has experienced both worlds and he understands how drastic the change has been. He's the most reliable when it comes to analyzing the new world. McCarthy uses examples and metaphors to describe very big themes and then wraps them up with a literal translation of what he's trying to describe.