Consider these words of George W. Bush, spoken in Rome, in 2001

“I know what I believe. I will continue to articulate what I believe and what I believe — I believe what I believe is right.”

This is not an isolated case. These sorts of fact-free assertions occur all the time. Consider another example, this one a hypothetical. Assume that you overhear some guy claiming that homeopathic medicine [or fill in the blank with your own favorite snake oil treatment] is effective and powerful. Because you suspect that he doesn’t have his facts right or that his reasoning is unreliable or invalid, you speak up and question his statement. He responds by saying something like the following:

I’m certain I am correct. I’m absolutely sure that I’m right. I have no doubts about this.

Despite the many claims of certainty that we hear, we often remain unconvinced, and for good reason. There’s a saying, “Show, don’t tell.” Show me the facts so that I myself can see whether I am certain. Don’t just tell me that you’re certain. Nonetheless, people constantly make claims that are based on inner feels of certainty, quite often wild and unsubstantiated claims about politics and religion, as well as claims about science, history or just about everything else.

People often use such claims that they have a “feeling of certainty” as bootstraps to convince themselves that they are even more certain than they actually are, thereby completely dispensing for the need for meticulous …