One approach to the interpretation of this long narrative poem by one of America's greatest poets is to read it as a metaphoric wall between political philosophies. With the speaker of the poem as the Liberal, so confident in his attitudes that are "progressive" and popular among so many, he approaches the mending of the wall with a light-heart, delighting in the Spring that brings him and his neighbor together. So self-confident is he that the repair of the stone wall is approached by him as "a kind of outdoor game"; he playfully works on his side replacing rocks, humorously telling them, "Stay where you are until our backs are turned!" But, when his neighbor--in the speaker's mind--unimaginatively recites his conservative belief that "Good fences make good neighbors," the speaker questions him, "Why do they make good neighbors?" and seeks to sway him to his way of thinking. But, when the neighbor refuses, the good temper of the speaker changes, and he calls his neighbor "an old-stone savage armed," perceiving him backward in his thinking without exerting any effort to understand him.
Juan Williams, formerly of PBS, who was fired because "I was not liberal enough," remarked that the "Liberal Orthodoxy will punish you if you disagree." Indeed, such seems to be the case here with the speaker, who disdains his neighbor for being entrenched in his conservative belief in the importance of boundaries, when he himself refuses to alter his maxim, "Something there is that doesn't love a wall" as he repeats, too, in line 35.
Certainly, then, the broader theme revolves around the fact that often people are so entrenched in their own beliefs that they refuse to consider those of others as viable, and they resent in them the intolerance of which they themselves are guilty. Another theme is that people often adhere to tradition for no other reason than that it is simply that, tradition, a ritual they have blindly followed for generations that to them possesses worth since it has been around so long:
He will not go behind his father's saying,
And he likes having thought of it so well
He says again, "Good fences make good neighbors."