I wasn’t going to blog about Newtown. “Mud of the place” and all that: my feet aren’t in the mud of that place, and I’m trying to watch where my mouth is.

On the other hand, I do have my feet in the mud of some of the issues involved, and have been occasionally spattered with the mud of some others. Whenever the news media descend on a place en masse and start talking when their feet have barely touched the ground — I’ve been there.

Whenever people start jumping to conclusions and misperceptions based on the reporting and commentating of people who have deadlines to meet and ratings to worry about and precious little mud on their shoes — Welcome to Martha’s Vineyard.

Last week I blogged about living in a place where I can leave my door unlocked and my keys in the car and walk in the woods alone after dark without fear. Earlier this year there was a shooting in my town. A man armed with a rifle and a pistol, Kenneth Bloomquist, broke into the home of his estranged wife, Cynthia Bloomquist. He wounded her. She shot and killed him, apparently with one of his own guns. The incident happened a mile or so up the road from me, but it didn’t affect my perception of my own safety, not then, and not now, almost nine months later.

I’m thinking about it now, though. The man was described by those who knew him as “volatile” in the aftermath of his marital breakup. He had threatened his wife in the past. She was worried enough to seek a restraining order. She didn’t get one. So — was this guy “mentally ill”?

In the coverage of the massacre at Sandy Hook Elementary School and in the discussions I’ve read, listened in on, and occasionally participated in, “mental illness” has loomed large. The shooter, Adam Lanza, had Asperger’s syndrome. Connection between the shooting and the syndrome? Possibly, but let’s not let mental illness overwhelm the other significant factors: the availability of firearms, the mother’s apparent survivalist proclivities, the possible influence of violent video games, and so on.

Many have called for improved access to mental health care, and for removing the stigma attached to mental illness. Yes and yes. But in one story I read, a medical professional estimated that the number of mentally ill people in the U.S. could be as high as 25 percent. 25 percent? With a figure that high, could we possibly be talking about the most serious forms of mental illness, the ones with chemical and/or physiological causes that can be treated, at least to some extent, with medication?

How about the “volatile” Mr. Bloomquist? How about the person who’s pleasant and soft-spoken when sober but a screaming banshee when drunk? (My mother was like that.) How about the person who’s thrown into a tailspin by the death of a loved one or a financial disaster? I’ve had times in my life when I was so low I wouldn’t have dared keep pills in the house, never mind a gun. Am I, or was I, “mentally ill”?

I just looked up “psychosis” on MedLine Plus, a service of the U.S. National Library of Medicine at the National Institutes of Health (NIH). “Psychosis,” it says, “is a loss of contact with reality that usually includes:

• False beliefs about what is taking place or who one is (delusions)
• Seeing or hearing things that aren’t there (hallucinations).”

It can indeed be caused by “alcohol and certain illegal drugs, both during use and during withdrawal,” as well as by several diseases and infections that affect the brain, and by certain prescription drugs.

Mental illness and psychosis are not synonymous: I understand that. I also suspect that someone who suffers from delusions and/or hallucinations, given the right (or wrong) conditions plus access to firearms, might snap and start shooting. And this condition is not necessarily the result of a long-term or permanent abnormal brain chemistry. It can be brought on by, among other things, alcohol or various other drugs. How to identify people who might snap? If it’s even possible, the number would probably be huge.

In the aftermath of Newtown, much attention has been focused on mass shootings by lone gunmen. (And they are, overwhelmingly, men.) I’ve heard them called “rampage killings,” as if the killer lost control, went nuts. But how about, say, Timothy McVeigh and Anders Breivik? They didn’t lose control. On the contrary: they were scarily in control. Each had a political purpose in mind and believed that killing a large number of people would serve that purpose. Were they “mentally ill”? What distinguishes them from the Ann Coulters, Rush Limbaughs, and others whose politics are just as hateful but who don’t act them out with guns?

How about people who take the Bible for the literal, historical truth, in the face of much empirical evidence that it isn’t? Are they “mentally ill”? How about members of the military, who kill when they are commanded to do so? How about the officers who issue the commands?

I’m thinking too of atrocities committed by ordinary, “normal” people: Srebrenica, Rwanda, My Lai, the Holocaust. In college I read Milton Mayer’s They Thought They Were Free: The Germans, 1933–45, about the ordinary people without whose participation Nazi Germany could not have become the horror that it was. I’ve carried that book in my head ever since. Standing outside the situation, we recognize those things as appalling. To them, though, those things were literally “normal” — what everyone around them was doing.

Slavery was once “normal” in this country. Now it isn’t. Now denying people health care because they can’t pay for it is “normal.” Maybe someday people will look back at us and wonder how we could have sanctioned such injustice.