James Gilligan makes it clear where he comes down on the issue. Gilligan, a psychiatrist and professor at New York University, presents his new book, “Why Some Politicians Are More Dangerous Than Others,”as a kind of murder mystery, or more precisely, a look at a mystery about murder, in which he includes self-murder, or suicide.

His inquiry explores why rates of homicide and suicide tend to increase together, and why those rates fluctuate so enormously over brief periods of time.

Gilligan tracked rates of suicide and homicide over a century, from 1900 to 2007 and was intrigued by the peaks and valleys he saw. Over that period, he writes, “I saw three large, sudden, and prolonged increases and decreases in these measures of lethal violence, which reached a peak and were then followed by equally dramatic decreases.”

He scratched his head over that until he realized that “all three of the epidemics of lethal violence corresponded with the presidential election cycle.”

Now, the next part of this item will get Republicans’ noses out of joint and will no doubt start Democrats thumping their chests. What Gilligan found was that suicides and homicides started climbing to epidemic levels following the election of a Republican president. If that isn’t annoying enough to the Grand Old Party, he also discovered that the rates remained around epidemic levels throughout the time Republicans occupied the White House. “The increase began during their first year or years in office, and peaked in their last year or years,” Gilligan writes.

And what happened when a Democratic president toodled up to the White House gate in a moving van? Those epidemic levels of violence, according to Gilligan, began to reverse direction in the first year or two of a Democratic administration and the rates reached their lowest point in the last year or years of the Democratic term.

Pure happenstance, right? Gilligan won’t hear of it — his analysis, he says, proves otherwise. The changes in the rates of violence occur “with a magnitude and consistency that could not be attributed to chance alone.”

So, what’s behind it? Gilligan uses an investigative technique that he says is similar to the one medical researchers deployed to establish a link between cigarette smoking and lung cancer. And he reaches a similar conclusion: “As cigarette smoking has been shown to increase the rates of lung cancer,” he writes “so the presence of a Republican in the White House increases the rates of suicide and homicide.”

The cause: policies. In Gilligan’s view, the policies of Republican administrations increase socio-economic distress which has all sorts of ramifications that lead to higher rates of murder and suicide, while Democratic administrations reduce socio-economic distress which aids the psychology of the masses and brings down the levels of violence.

Gilligan’s book, published last month by Polity Books, will, if nothing else in our summer of political discontent, get both sides howling over its conclusions.

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