Elvis, songwriting, and politics

(CNN) -- Elvis Costello has never shied away from politics. "Armed Forces" is all about politics; the song "Tramp the Dirt Down," from "Spike," is as angry an anti-Margaret Thatcher diatribe as was written during the Iron Lady's 11-year rule.

But he prefers to take the long view.

"I don't necessarily think you're obliged to comment on everything that happens in the world," he says. "I think in a world where most politicians are more concerned with approval ratings, and they're more akin to advertising people than they are statesmen, it makes it very difficult to write anything about them. They don't hold that position long enough to comment on."

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Besides, songs that comment generally on the human condition are longer-lived than songs about a specific person or issue, he says.

Costello compares one early Bob Dylan song, "The Lonesome Death of Hattie Carroll," with the later "It's Alright Ma (I'm Only Bleeding)." The former is "an extraordinary song," but it was obvious why Dylan took a different approach, he says.

"The lesson learned from that still resonates with a lot of people," he says. Songs like "It's Alright Ma" opened pop music up to a whole new kind of songwriting. "Dylan sort of let the cat out of the bag, and it's a big old cat with big fangs and you can't get it back in the bag."