For years now I’ve been arguing that much of what passes for wisdom is really one-sided half-truth. Last week, for example, I argued that, “be present” is a half truth. The whole truth is that you should be present to some things and not to others and that the trick is to figure out what in the long run proves worthy of your attention.

You can’t be present to everything. It’s physically impossible. You could decide to be present to the false impression that you are present to everything. Even that is being selectively present.

People have their reasons, so why are so many therapists, gurus, coaches, psychologists, and self-help guides so very present to these half truths? And why are so many of their clients present to them too? Why is it so hard to get people to be present to the two-sided truths like “be present to somethings and not to others?”

Here’s a guess:

Psychologists aim to be scientists working to understand human behavior accurately. But they are also helpers trying to convey what will change counterproductive behavior. And the truth is that sometimes what’s useful isn’t true and what’s true isn’t useful.

A philter is a magic potion with the power to change you. A filter is a screen that lets only some stuff through. Therapists, gurus, coaches and self-help guides tend to provide philters, filtered arguments that remove some truths so as to emphasize the partial truths they believe will help their clients.

They really want to help their clients so they do what they can to make sure their philters to be potent not watered down. That’s a reason to deny that they’re filtering. Don’t tell an egomaniac that ego is sometimes necessary. Tell him to “always be selfless.” Cut the truth 50% but claim it to be 100% complete.

If you worry too much, take a philter that says “don’t sweat the small stuff and it’s all stuff.” If you nag your partner too much take a philter that says that “there is never a reason to call your partner on his bad behavior.” If you tend to be so distracted that you’re not productive, take a philter that says “always be present.”

Even at their supposed full potency these philters won’t be powerful enough to change you completely, but that’s fine. In fact that’s a good thing given that the truth is that you’re best off worrying some (about the right things), nagging some (about the right things and in the right way) and thinking about the past and future (in the right ways).

This month I’m employing a zero tolerance policy on carbohydrates. I’m taking a philter that says carbs (which I love) are absolutely bad for me. Of course they aren’t, so my inability to comply completely is a good thing. By absolutely no carbs I mean absolutely not probably that many I hope really.

So take whatever philters help you out in your current situation, but recognize them for what they are. They’re filters, filtering out as much as one full half of what constitutes real wisdom, for example the wisdom to know the difference between what you can and can’t change in your partner. And remember that filtering out the wrong half of wisdom can be dangerous.

We are drawn to magic potions that help us change our powers but also to potions that help us maintain our powers, even powers that are way out of balance.

Taking a philter that argues the virtues of ignoring your partner’s faults is a great way to offset a habit of nagging your partner. In that context, it’s an attempt to change one’s powers. But in the hands of people who already overlook too many of their partner’s faults that philter becomes dangerous.

A woman in an abusive relationship tries to call her partner on his abusiveness. He dismisses her, saying his abusiveness is “no big deal.” She’s too accommodating for her own good as it is, and then a well meaning but misguided friend hands her an article that counsels that it’s always best to overlook a partner’s faults.

Or suppose her bullying husband gets hold of some self-help book saying it’s always best to stand up for oneself. Suppose a recklessly irresponsible person gets hold of “don’t sweat the small stuff.”

I knew a woman once who was having an affair with a married man just as her own husband was struggling with colon cancer. At the time her favorite book was “Don’t sweat the small stuff and it’s all small stuff.” It was her sacred source of justification for behaviors she later regretted.

That book was the wrong medicine for her and yet there was no warning label. Philters that imply that they’re the absolute truth are like ADD meds labeled “Good for the whole family!” They would calm the hyperactive family members, but could give the non-hyperactive members heart attacks.

Perhaps self-help books should come with as many warnings as pharmaceuticals do. Or at least some kind of warning label.

My philters are all about the importance of seeing both half truths at once. They’re philters against filters. They’re spirits in the spirit of the famous F. Scott Fitzgerald’s quote:

“The test of a first-rate intelligence is the ability to hold two opposing ideas in mind at the same time and still retain the ability to function.”

Are my philters for everyone? Certainly not. If you’re someone who needs closure and clarity, a real plan of action or a real compensation for a strong tendency to be wishy-washy, take the proper potion to persuade yourself. The sign of a first-rate intelligence may be the ability to know when you need to hold two opposing ideas in mind at the same time and when you need to hold just one, and filter out its opposite.