Why internal consistency in stories matters

Jack Reacher, created by starryai.com

 Internal consistency. 

This is something I discovered needs to be present throughout the series, or even a story. The realisation came while reading Jack Reacher novels by Lee Child. I understand that the author leaves the protagonist as a mostly blank slate. Gives him the manoeuvring space and allows the reader to imagine himself as Reacher. That at least is the theory. If we agree with that, is something else. 

Child likes to pay lip service through Reacher to the cause of the day, to show how hip and with times his hero is. All well and fine. But it's jarring when there is no reflection on the hero's actions that contradict his beliefs, even if they were meant as lip service. 

Example: Reacher states that women are as capable as men in combat. He trully believes that. And then later on with one swing he accidentally snaps the neck of a female serial killer who got in his way. 

Another example is the way he is extorted into helping FBI. Through previous books it's established Reacher doesn't let bullies get away with it no matter who they are. He's going to tolerate them as long as they're pestering him, but if they go after someone innocent or someone he likes, the gloves are off.

 So the way in which Reacher helps FBI because they threaten to doxx his girlfriend, and thus put her life in danger from a local crime lord is just stupid. Especially when you take in consideration that one call from Reacher to the highest echelons of FBI would get him rid of those wicked agents, because they owe him from previous books. 

But we're supposed to just accept it, so the story can happen, even when that same story could happen while also staying true to the character. 

I draw comparison with another thriller author, Tom Clancy. He also loved to pay lip service to the cause of the day, but he had the wisdom to do it in a way it didn't come back to bite him. 

Example: Women are as capable in leadership positions as men. Prime example through Jack Ryan series is the head of Secret Service. Clancy acknowledges that in normal circumstances she could never become the head of the secret service, but once the opportunity arises, Clancy has her rise up to the occasion and demonstrate her capabilities in action. 

When there appeared an incapable woman in leadership position Clancy went to great lengths in order to demonstrate she wasn't incapable because she was a woman, but because she was promoted to the position without merit. 

In short, it is often said, show don't tell. With internal consistency is show what you tell, or at least acknowledge how the actions that contradict already stated facts influence the beliefs of the characters.

 It doesn't have to be much, it doesn't have to be definitive, but it has to be acknowledged. One simple sentence can make a world of difference. 

For example: "Reacher always believed women were as capable in combat as men, and then he remembered X lying on the bathroom floor. He thought she just passed out, but in truth she was dead." Something like that. It doesn't have to mean the hero immediately radically changes his views. It just has to show the reader that the hero has minimum reflection on things happening to him.