I will oversimplify a bit here.
The book MISTAKES WERE MADE BUT NOT BY ME uses a pyramid as an example of
how some people can be so far gone from rational or normal thoughts on a matter.
At the top of the pyramid, a matter is presented. One person makes a small choice that is
different from someone elses small choice. That makes him go down a different side of the
pyramid. First, the difference between his position and that of someone is is negligible. He's
near the top of the pyramid still.
As time goes on, he reinforces his different decision with other supporting decisions or thoughts.
His cognitive dissonance causes him to comfort his mind. He slides down that pyramid. Others
are doing the same on the opposite side of the pyramid. They are justifying and dealing with their
dissonance and sliding the opposite way on their pyramid. Eventually, the two groups are as
far from each other at opposite corners as they can be.
Before he realizes it, a person finds himself doing things or believing things that anyone on the
other side of the pyramid would never do or believe. JW's are doing that with the WTS now. They
are so sure that they must be in the right religion that they make excuses for the religion, no
matter the evidence to the contrary. The same could be true for Nazis or black gay men who think
they are Jesus.
Police chose to be 100% certain that the accused party was guilty somewhere early on in their
investigation. Because they were 100% convinced, they saw nothing wrong with deceptive interrogation
methods. They saw nothing wrong with forcing confessions out of people. Later, when DNA actually
proved the accused was innocent, some police would scoff at the DNA evidence. If given the chance
to suppress evidence, they might do that because "After all, the guy IS guilty." If confronted by others
who want to know why they used deceptive interrogation methods, they say that they only do this to
guilty people. They don't understand how this already reveals that they made up their minds before
establishing guilt or innocense.
Many of these same police- later when they see that they sent innocents to jail- cannot imagine how
they got that far from the top of the pyramid on this side of the slope.