Remember that we treat ideas like possessions, and it will be hard for us to part with them. —Nassim Nicholas Taleb, The Black Swan

Many of our ideas are based on what could be called common sense or conventional wisdom. They just seem so obvious we never consider questioning them. Because they make sense to us, we operate as if they are factual. We don’t need to know if there’s any evidence to support them. But those kinds of ideas are actually beliefs: things we accept or trust to be true. And when it comes to beliefs, trust generally trumps the need for evidence.

Here are two recent examples where evidence doesn’t support the conventional wisdom. Both involve children and child-rearing attitudes.

The conventional wisdom is that parents’ involvement with their children’s schooling is advantageous to their children’s education. That just seems like common sense. But this belief had never actually been tested or measured until recently. And it turns out that the conventional wisdom is not all that wise.

Don’t Help Your Kids with their Homework and other insights from a ground-breaking study of how parents impact children’s academic achievement: Parents can impact their kids academic success, but not by helping them with their homework, especially when the kids get to middle school.

Other conventional wisdom in regard to kids is that the world is a more dangerous place than it used to be, and the primary job of adults is to keep kids safe. This also seems obvious. But it’s also a belief that isn’t often examined. It turns out that the world may not be that much more dangerous than it used to be, and the zealous overprotection of kids may be doing them more harm than good.

The Overprotected Kid: A preoccupation with safety has stripped childhood of independence, risk taking, and discovery—without making it safer: Kids need to have time away from the watchful eyes of their parents or other adults, and they need to experience a feeling of being in danger in order to develop into competent adults.

There are many more examples of evidence not supporting the conventional wisdom in other areas, especially aging and behavior. In the two instances cited above, I think it’s interesting to consider how these beliefs may have been formed and how they became so widely accepted. It’s generally harder to find a middle ground when beliefs are involved because beliefs have such a strong emotional component.

And that’s another area in which common sense or conventional wisdom fails us. We think the level of confidence we have in a belief has some positive correlation with the accuracy of the belief. But it doesn’t. In fact, there’s probably little evidence to support many of our beliefs.

Declarations of high confidence mainly tell you that an individual has constructed a coherent story in his mind, not necessarily that the story is true. —Daniel Kahneman, Thinking, Fast and Slow

The bottom line is that our brain craves certainty, and beliefs provide us with a feeling of certainty. If we want to use our brain, however, we need to challenge some of our own deeply-held beliefs instead of doing everything we can to shore them up. That’s easier said than done, of course.