In discussion with friends, there was the question of what goes through the mind of someone like Joe Paterno. Based on what I've learned from reading "Mistakes Were Made (But Not by Me): Why We Justify Foolish Beliefs, Bad Decisions, and Hurtful Acts" I think I have some ideas on how this works. And it's actually quite simple. It's a matter of taking it one step at a time until you find yourself beyond a "point of no return."
It could possibly have started out with Paterno convincing himself that "Sandusky is a good man. He wouldn't do that!" Later, Paterno would find out that Sandusky would indeed do that. Then the justification would be along the lines of "Sandusky is still a good man! He's just a little troubled, but there is no reason to taint or even ruin his reputaion and career by bringing the police into this. If we just support him, he will get over this." There will be little to no consideration of the victims in this justification. The cognitive focus will be on the abuser. After all, that is who Paterno knows; he is not emotionally attached to the children being harmed. As horrible as it sounds, this makes them easier to dismiss from the equation.
At some point, Paterno may have realized that Sandusky is not going to just "get over this." But by this point, he is too committed to change course; he is beyond the point of no return*. He knows that if he goes to the cops now that they will be wondering why he didn't act sooner. When word reaches the media, they will be asking the same questions. See, Paterno has already acheived the roll of accomplice. He knows this. He is no longer just protecting Sandusky; he is also protecting himself, and he likewise turns his rationalizing on himself as well. Now it's "I'm a good guy, but they will treat me as though I am not!" The desire to protect one's own image, unfortunately, all too often is greater than the desire to protect others, in this case, the children that Sandusky was abusing.
And Joe Paterno has had a very positive image to protect, as should be evident by the way people have been supporting Paterno. This is also why I am disgusted with their reactions. They are demonstrating the same cognitive processes - protecting the public image of a person - that leads to such cover ups.
* The idea of the "point of no return" is that if the person who has been justifying bad behavior stops doing so after this point, their personal reputation will be damaged. They can never be entirely guilt free from their actions. Whereas, if they had stopped justifying early on, they could have been forgiven and no damage would have been done. However, many people wrongly decide to avoid damaging their own reputations by continuing to justify bad behavior instead of fessing up. The reason this is the wrong decision is that, if and when the bad behavior is discovered by outsiders, the damage to one's reputation becomes much worse. In the third paragraph, I talked about how Paterno had reached the point of no return. If he would have reported Sandusky at this point (and it's hard to know exactly where that point is - it's mostly an arbitrary point), his reputation would have been slightly damaged. However, as a result of people finding out about Sandusky through other means, Paterno's reputation is now quite damaged.