MAKING POSITIVE STATEMENTS to yourself when you feel down improves your mood — but only slightly. Thirty years ago, that was the best you could hope for. But since then, an enormous amount of research has been done on exactly how our thoughts affect the way we feel. This is the realm of cognitive science.

The most important insight from cognitive research is this: When you feel angry, anxious, or depressed, those feelings are largely caused by irrational (unreasonable) assumptions.

Of course, circumstances call for some kind of response, but your response will depend on your habits of thinking. When you’re in the habit of making faulty (irrational, unreasonable, unjustifiable) assumptions in response to certain kinds of events, you’re likely to feel a lot of anger, anxiety or sadness in that area of your life.

Cognitive science says, “Rather than trying to think positively, find out what’s wrong with your negative thinking. If you’ve got strong negative feelings, your thinking is inevitably distorted, unsubstantiated and overgeneralized.” Criticizing the assumptions behind your negative feelings measurably and significantly improves your mood. When you find yourself making an unreasonable assumption and it makes you feel bad, attack the assumption. Check it for illogic. See if you’re exaggerating or ignoring evidence.

Give your own negative thoughts the same treatment you would give to the statements of a fast-talking salesman: Question them without mercy. Don’t assume that something is true simply because you thought it. Check your own thoughts against logic and evidence as skeptically as you would the thoughts of someone else. You are fallible like any other human being, and you are capable of thinking thoughts that are not only untrue, but also counterproductive.

If you’ve got the time, criticize your assumptions on paper. Write an assumption you’re making — something you think is true about the situation, some assessment or opinion you have — and then write out all the reasons why that assumption may not, in fact, be true, and why it may be a supremely stupid thing to think. This is one of my favorite methods. When I do this, I often use two pens of different color, one for the assumptions and one for my criticisms of those assumptions.

Old-style positive thinking — the kind of pollyanna, rose-colored glasses, everything-happens-for-a-reason positive thinking — ignores an important issue: truth. And that’s why it doesn’t work very well. Thinking positively only works if you believe it, and it’s very difficult for a modern, educated, rational person (you, for instance) to believe something just because it’s a nice thought.

Don’t bother with positive thinking. Something much better has been discovered. When you feel mad, annoyed, frustrated, stressed, worried, or down-in-the-dumps, pay attention to your thoughts and then argue with those thoughts on the basis of evidence and reason. At the moment you recognize one of your negative thoughts as irrational, you’ll feel better.

You may have to argue with the same thoughts over and over again, sometimes for months, but eventually you’ll get in the habit of making more rational assumptions, and the more rational your thoughts, the less you’ll be troubled by the negative emotions your thoughts were causing. When you’re no longer burdened by unnecessary feelings of sadness, anger, and fear, you’ll find your general mood and sense of well-being will rise to a new level. Cut yourself free of needless negative emotions with the blade of rationality.