Consider the following:

A bat and ball cost $1.10.  The bat costs one dollar more than the ball.  How much does the ball cost?

Daniel Kahneman in Thinking, Fast and Slow indicates that your initial response is probably 10 cents – it is intuitive, appealing, and wrong.  If the ball costs 10 cents then the total cost is $1.20. The correct answer is 5 cents (p. 44).  Why do we make these mistakes?

He points out that we have two basic types of thinking:

• System 1 operates automatically and quickly, with little or no effort and no sense of voluntary control.
• System 2 allocates attention to the effortful mental activities that demand it, including complex computations.  The operations of System 2 are often associated with the subjective experience of agency, choice, and concentration.  (p. 20-21)

System 1 is our default system and if it has difficulty it will rely on System 2 thinking.  A problem we face however, is System 1 doesn’t know when it is wrong.  We have all seen the The Müller-Lyer Illusion:

We can only process what we take in – take a look at the Selective Attention Test. Just as we have all experienced visual illusions we also experience cognitive illusions.  Here’s another one for you:

A driver with a gas-guzzler of 12 mpg changes to a car with 14 mpg whereas the environmentally minded person with a 30mpg car upgrades to a car with 40 mpg.  Suppose both drivers travel equal distances over a year, who will save more gas by switching?

Intuitively it appears to be the environmentally minded driver since the mpg was reduced by 10 rather than 2 and by a third (from 30 to 40) rather than a sixth (from 12 to 14).  Take some time and use System 2 thinking and work out the problem.  If both drivers travel 10,000 miles then the gas guzzler goes from 833 gallons to 713 gallons for a savings of 119 gallons.  The environmentally conscious car will drop from 333 gallons to 250 saving only 83 gallons (p. 372).  The use of mpg rather than gallons per mile is the reason you are misled.  It is interesting that many European countries reframe the problem looking at liters per 100 kilometers.

What is the take away from this book?  “The way to block errors that originate in System 1 is simple in principle:  recognize the signs that you are in a cognitive minefield, slow down, and ask for reinforcement from System 2” (p. 417).  The writer of Proverbs cautions us,

There is a way which seems right to a man, but its end is the way of death.  (Proverbs 14:12, 16:25)

You may not be facing a life or death situation but you can avoid some cognitive errors by slowing down your thinking.  Where do you often see System 1 errors?

Dr. Rick Higgins
Professor of Discipleship, Columbia International University