Why does Cormac McCarthy in 'The Road', not give his character's names? How does the labels 'boy' and 'man' affect the way readers relate to them?

In "The Road" the author does not provide names for his characters because it makes the story's theme of the violent indifference that has stricken the world more intense, it conveys how this devastation has stripped us of our individuality, now those who have survived wander in a rugged, raw new wilderness, fighting to stay alive.

The bleakness, coldness and indifference that is conveyed through the impersonal nature in this story helps to support the author's message of the total destruction of everything that we love and appreciate about our lives.  

"The boy and his father hope to avoid the marauders, reach a milder climate, and perhaps locate some remnants of civilization still worthy of that name. They possess only what they can scavenge to eat, and the rags they wear and the heat of their own bodies are all the shelter they have. A pistol with only a few bullets is their only defense besides flight."