What this country’s founders had in common was, more than anything else, the Enlightenment — an intellectual heritage that considered evidence and reason to be superior to faith, tradition, and authority as ways of understanding the world.

By 1800 the Enlightenment was already in decline, supplanted by world views that placed more stock in emotional ways of knowing.

Ten years and a day ago, 19 individuals who placed their faith in tradition and authority attacked this country, sacrificing themselves in doing so.

Their attack was, in a very real way, an attack on our Enlightenment legacy. But while much of how we responded was admirable, a re-commitment to that legacy was not part of our national conversation.

How we think about what “to know” means is very much part of the American experiment, and should not be a matter of fashion. But right now, in America, Enlightenment thinking is out of fashion.

I’ve seen first-hand an all-too-common response when someone frames problems and solutions in terms of evidence and logic: Dismissive eye-rolls by those who consider “I trust my gut” to be the alpha and omega of decision-making technique, as they explain to each other that “… of course he deals with the world this way … he is, after all, a technician, incapable of looking at the big picture.”

Here’s how bad it is: Mexico — a country with a third our population and an economy one tenth as large, has 20% more students enrolled in undergraduate engineering programs than we do. Clearly, young Mexicans see engineering as a route to affluence and respect. Young Americans consider it a path to harder work, a lower career ceiling, more limited wages, and less respect than what they can achieve through less intellectually demanding alternatives.

(They are, by the way, half right, but also half wrong. More S&P 500 CEOs earned undergraduate engineering degrees than any other major. But as a path to CEO-hood, engineering ranks below Operations, Finance, Marketing, Sales, and Planning & Development — source: “Leading CEOs: A Statistical Snapshot of S&P 500 Leaders,” SpencerStuart, 2006.)

It’s popular these days to talk about different ways of knowing as if they’re all equally valid. From the perspective of personal happiness, perhaps they are. From the perspective of career success they probably are as well, hence the well-known value of “emotional intelligence” as compared to, say, actual intelligence.

Okay, that was a cheap shot, and, worse, one that devalues an important ability –interacting effectively with other human beings.

Which doesn’t affect the point in the slightest. As evidence I offer Ben Franklin’s autobiography — a wonderful and wonderfully readable document by one of America’s leading followers of the Enlightenment. In it he offers quite a few situations that led him to discover effective principles for working with other people.

Here’s what this means: Engineers and others who base their professional success on the use of evidence and logic can use their engineering thought process to become better at interpersonals. Those who reject the “left-brain” approach to things can’t, however, use their emotional intelligence to become better engineers.

There’s a danger here: Claiming intellectual superiority over their more intuitive colleagues is an easy trap for technical professionals to fall into. Except for subjects like belief and aesthetics, evidentiary decision-making is certainly superior to intuition — the world did, after all, turn out to be round. But there’s a difference between the superiority of an approach and the superiority of the person taking it.

We’ve all been in conversations in which someone … sometimes a person with considerable experience and success … says that while they can’t explain their position, they’re pretty sure they’re right about it.

Often they are. Sometimes, the inability to explain comes from too much knowledge and experience rather than too little — the person has consciously run through the logic of similar circumstances so often that they’re no longer conscious of what they’re doing, very much as a guitar player might have a hard time explaining which fingers do what, exactly, when playing a difficult piece.

The inability to explain, that is, doesn’t make a person wrong. Unpersuasive? Yes, which is why the onus is on them to understand their internal logic well enough to explain it.

Do engineering and the other STEM disciplines (science, technology, engineering, and mathematics) belong in the Enlightenment category? Yes, of course they do, which is different from placing all scientists, technologists, engineers, and mathematicians there.

We are just as subject to human foibles as anyone else. And when we succumb to them, we are, if anything, more dangerous, because if we aren’t careful, we’ll use our expertise at applying evidence and logic to rationalize decisions we made just as irrationally as anyone else.

Do you work for a psychopath? Someone who’s just plain nuts? One of the crazies mentioned last week?

Nuance is an overused word and underused way of looking at the world. Our thinking about mental illness could, for example, use much more of it. There are those who think we create syndromes for every idiosyncrasy that’s a decimal point away from some mythical state of normalcy – that we use syndromes as excuses so nobody is responsible for anything they do. It’s the syndrome’s fault, and there must be a medication to take care of it.

There are also those who consider the increased diagnosis of mental illnesses to be progress … a way to understand people who do suffer from very real medical and psychological challenges and need help, not criticism or opprobrium.

Then there’s Jon Ronson and his book The Psychopath Test: A Journey Through the Madness Industry (2011). Ronson manages to avoid, not only both extremes, but the “fairness trap” as well. He doesn’t take a middle ground. He takes a nuanced ground, where the conditions and syndromes we all know about are both real and tragic when they happen, and over-diagnosed and often over-medicated as well.

It’s a world where attention deficit disorder can be both a real problem for real human beings, and a convenient excuse for not paying attention for others who are perfectly capable of paying attention if they didn’t have ADD to fall back on.

It’s a world where criminal profiling yields both startling successes and alarming miscarriages of justice.

And, it’s a world where Robert Hare’s PCL-R checklist provides both real and useful help in recognizing seriously dangerous individuals, and is also over-used by armchair experts who cheerfully label as psychopaths anyone who isn’t as sympathetic as we might prefer, including not a few business executives, and the crazies described in last week’s column.

The PCL-R checklist, in case you’ve never heard of it, is the gold standard diagnostic for sociopathy (or psychopathy … the terms are interchangeable). It lists symptoms like impulsiveness, lack of empathy or remorse, and pathological lying as key indicators of the syndrome.

Oddly enough, it appears true psychopaths are not “bad people” in any meaningful use of the word “bad.” Psychopathy apparently has a physiological cause – an under-active amygdala compared to “normal” human beings, which very likely is why their ability to feel and respond to emotion is so limited. It’s a real and thus-far untreatable condition.

This makes them no less dangerous, of course. If you work for or with someone who has these tendencies, the only trust you can put in them is your trust in the predictability of their behavior … namely, that they’ll do whatever they feel like doing without compunction, scruples, or concern over the possible consequences.

And it’s worse, because true psychopaths are superb manipulators. They’re charming, glib, and excellent at figuring out the levers and buttons they can pull and push to get people to do as they’d like.

Including you, unless and until you catch on. And when you do, there will be nothing you can do about it as you watch executives, managers and employees all around the company fall for it. And if you raise a red flag, they’ll brand you as a backstabber.

Office psychopaths are better at manipulating than you are at persuading. As playing someone else’s game is for chumps, you’re better off not trying.

If you take the time to learn the PCL-R checklist you’ll be surprised at how many of the top people in your company score high. It’s a scary thing.

But if you take the time to read The Psychopath Test you’ll realize something else as well: If you apply the checklist to someone you dislike, you’ll focus on those behaviors that match up to it, while ignoring the ones that don’t, just as, applying that same checklist to someone you like, you’ll do the exact opposite.

It’s something we humans do all the time – latch on to whatever evidence supports our preconceived notions while filtering out or finding reasons to wave off whatever doesn’t.

So the next time the company crazy does something that … well, that drives you crazy, try to consciously reverse your filters. See the world through the crazy’s eyes. Empathize.

You might find they aren’t horrible psychopaths after all. They might just be doing what they have to do to deal with the pressures some other psychopath puts them under.