Closed-minded people say things like “I could be wrong . . . but here’s my opinion.” This is a classic cue I hear all the time. It’s often a perfunctory gesture that allows people to hold their own opinion while convincing themselves that they are being open-minded. If your statement starts with “I could be wrong” or “I’m not believable,” you should probably follow it with a question and not an assertion.

Open-minded people know when to make statements and when to ask questions.

Closed-minded people block others from speaking. If it seems like someone isn’t leaving space for the other person in a conversation, it’s possible they are blocking. To get around blocking, enforce the “two-minute rule” I mentioned earlier.

Open-minded people are always more interested in listening than in speaking; they encourage others to voice their views.

Closed-minded people have trouble holding two thoughts simultaneously in their minds. They allow their own view to crowd out those of others.

Open-minded people can take in the thoughts of others without losing their ability to think well—they can hold two or more conflicting concepts in their mind and go back and forth between them to assess their relative merits.

Closed-minded people lack a deep sense of humility. Humility typically comes from an experience of crashing, which leads to an enlightened focus on knowing what one doesn’t know.

Open-minded people approach everything with a deep-seated fear that they may be wrong.

Once you can sort out open-minded from closed-minded people, you’ll find that you want to surround yourself with open-minded ones. Doing so will not only make your decision making more effective but you’ll also learn a tremendous amount. A few good decision makers working effectively together can significantly outperform a good decision maker working alone—and even the best decision maker can significantly improve his or her decision making with the help of other excellent decision makers.