Train Your Brain: Should You Avoid Using Rules of Thumb?

Be suspicious of any quick answer

“I saw a plane crash on TV last night, so I’m cancelling my trip.”

This is using a rule of thumb to make a decision. A plane just crashed, so I’m avoiding planes.

A little research before making this decision, would have told you that in the U.S. more than 40,000 people died in auto accidents last year and during the last 10 years combined, less than 50 have died in plane crashes.

A rule of thumb is a simplified approach to solving a problem. Our brain utilizes rules of thumb to estimate things and drive behavior.

What are the advantages and disadvantages of using rules of thumb?

Key Results




Quick answer



No wasted time

False sense of urgency


Seems accurate

Often incorrect

Part of the problem with rules of thumb is that our own experience gets in the way.

If our experience with teenagers working behind the counter at McDonalds has been unpleasant, we may assume most or all teenagers are unpleasant as waiters, parking-lot attendants, etc. 

These experiences feed into the sloppiness of using a rule of thumb to make a decision.

Don’t do it!

When making important decisions, always consider a few simple guidelines to help avoid rules of thumb and train your brain:

  • Don’t over-rely on your experience. Easy to say, but difficult to do. If you can train your brain to think objectively, you are on the way to success.

  • Understand that all decisions are made with less-than-complete information. There is a fine line between using a rule of thumb and doing a little work to make that decision.

  • After the decision was made, do not assemble facts that support the decision. Assemble the facts before you make the decision. Don’t be that person who never speaks up but has 20-20 hindsight when things go wrong.

For more stories about how to train your brain to avoid rules of thumb and quick and dirty thinking, read here.

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