Brokaw, an honorable and industrious man, is now playing the role of elder statesman while touting his new book, “The Time of Our Lives.” In it, he writes: “Slashing rhetoric and outrageous characterizations have long been part of the American national political dialogue … but modern means of communications are now so pervasive and penetrating they might as well be part of the air we breathe, and therefore they require tempered remarks from all sides. Otherwise, the air just becomes more and more toxic until it is suffocating.”

There’s much wisdom here. But blaming the new media environment for what ails us is an awfully convenient alibi. It suggests that the old media, of which Brokaw was a master of the universe, played no part in losing the trust of so many Americans.

For starters, when the mainstream media complains about the national “tone,” it almost invariably means the tone to their right. After the tragic Gabrielle Giffords shooting, the mainstream media reported, and liberal pundits raced to insist, that Republican rhetoric — particularly, a pictogram on Sarah Palin’s Facebook page — inspired the suspect. The evidence disproving all of that is voluminous; the record of apologies and retractions from those who reported it is comparably scant.

At the same time, Democratic rhetoric has grown ever more extreme.