In the aftermath of the senseless wounding of Representative Gabrielle Giffords, Democrat of Arizona, and the murder of six others, including U.S. District Judge John Roll and 9-year-old Christina Green, there will be many who will use this tragedy to advance their own political agendas.

Explanations will be sought and blame assigned. Necessary questions will be asked: Did the clerk at the Sportsman’s Warehouse in Tucson violate any laws in selling the Glock 19 9mm gun to the accused, 22-year-old Jared Lee Loughner? Loughner reportedly cleared an FBI background check. So why didn’t that check discover what one Arizona official called Loughner’s “mental issues” and should they have disqualified him from purchasing the weapon?

Former Alaska Governor Sarah Palin is being criticized because she “targeted” some Democratic members of Congress for defeat in the November election, superimposing crosshairs on their districts on her SarahPAC website. Rep. Giffords was one of those “targeted.” At the time, Giffords criticized the display saying people need to be “responsible” for their actions. Left-wing bloggers blamed Palin for contributing to the poisoned political atmosphere, but that explanation is too easy.

Next week is the 50th anniversary of President John F. Kennedy’s inauguration. Less than three years later, left-wing Soviet sympathizer Lee Harvey Oswald assassinated Kennedy. Were liberals to blame for that horrific killing? Of course not. The assassins of Presidents William McKinley (an unemployed anarchist) and James Garfield (a disgruntled man rejected for a diplomatic post) lived in an era free of talk radio and cable TV. Radio, TV and social media didn’t exist when actor John Wilkes Booth, a confederate sympathizer, shot and killed Abraham Lincoln. More gun laws would not have stopped Booth, or the others for whom laws against murder were not deterrents.

The best “explanation” for this horror came from Arizona Republican Senator John McCain. In a statement, McCain put the blame where it belongs, on “a wicked person who has no sense of justice or compassion.” He added, “Whoever did this; whatever their reason, they are a disgrace to Arizona, this country and the human race, and they deserve and will receive the contempt of all decent people and the strongest punishment of the law.”

That is moral clarity. It places blame where it should be, on the shooter. Many people listen to talk radio, or watch political debates on cable TV. They don’t then pick up a gun and attempt to assassinate public officials.

Pima County, Arizona Sheriff Clarence Dupnik, a Democrat, denounced what he said is the nation’s vitriolic political climate: “The anger, the hatred, the bigotry that goes on in this country is getting to be outrageous.” He said Arizona had become “the mecca for prejudice and bigotry.”

Anyone familiar with political discourse in America knows it has been rough and tumble from the beginning. Long before modern media, newspapers condemned politicians they didn’t like, questioning their character and moral fiber. To end vibrant, even incendiary political rhetoric, would require the eradication of politics, itself. Other countries have such a system. They’re called dictatorships.

Evil exists and a few are possessed by it. C.S. Lewis said that evil isn’t an absolute; it needs good. It’s a parasite that rides on good.

G.K. Chesterton offered an explanation for evil we may not want to hear, because it places blame where we like it least: “Men do not differ much about what things they will call evils; they differ enormously about what evils they will call excusable.”

We tolerate, even promote, many things we once regarded as evil, wrong, or immoral. And then we seek “explanations” for an act that seems beyond comprehension. Remove societal restraints on some evils and one can expect the demons to be freed to conduct other evil acts.

The fault, as Shakespeare wrote, “lies not in our stars, but in ourselves.” Once tolerated, evil grows like the parasite alluded to by Lewis. It inevitably and predictably leads to other evils, like the tragedy in Tucson.

© 2011 TRIBUNE MEDIA SERVICES, INC.