The Conjunction Fallacy Explains Why People Believe Fake News

John Allen Paulos in Slate:

Imagine there are 100 toy blocks in front of a toddler. Each of the blocks costs $1, 50 of them are red, 50 blue, and to build a sturdy little house requires about 75 or so blocks. By necessity the house will contain blocks of both colors—even if the child is partial to one of the colors.

Now imagine a new manufacturing technology comes along and makes it possible to make these blocks for 1 cent each. Parents can now buy sets of 10,000 blocks, 5,000 red ones and 5,000 blue ones for the same amount of money. The toddler again makes his or her house, but if partial to one of the colors, he or she can easily find 75 blocks of the same color and make an all red house, or an all blue house, or a monstrosity of a mansion.

The new technology is the internet. The red and blue blocks are news stories, colored according to whichever world view they represent, and the houses are meta-stories we toddlers tell ourselves. Thanks to the vast amount of information (or misinformation) on the internet, we are all able to build houses of just one color. Nowadays, we can all easily be misguided by confirmation bias, our natural tendency to search for information that confirms our beliefs and to ignore that which threatens our beliefs. The consequence, if we don’t check our unexamined predilections, is a world that is made entirely of single-colored houses, some red, some blue. And too many single-colored neighborhoods can lead to skewed beliefs.

More here.