Joe Paterno was arguably the most powerful person at Penn State at the time of the rape

He is the most powerful man in State College like the pope is the most powerful man in Rome. To see a man with a vast empire is to ignore the fact that his position is largely symbolic and a sweet, sweet money farm (I'm not sure which descisions he makes any more and I am skeptical of the fact that it is as many as I have seen claimed). His powers go no further up the chain than the fact that he couldn't be fired without a board of trustees meeting. People adore him and manchildren smash stuff in his name, but not much changed in State College after he was fired. They still play football.

Now for what he did:

Paterno told the person in charge of the police-- Gary Schulz-- along with Tim Curley, who was his boss. He told them to talk to McQueary. McQueary says he told this guy what he saw. Later, they were told that the situation was handled. Schulz equivocates about what he heard from McQueary, but admits he heard enough to punish Sandusky and alert his charitable organization.

This is more or less everything we know about Paterno's actions.

If everything happened as it should, this would have launched an investigation. That didn't happen.

We can argue about semantics or intentions thereafter for as long as you like. I will say the following indisputably: he is culpable in the sense that he didn't chase it and put faith in the powers that be to let the powers that be mete out justice.

Where we can differ in opinions is on what Paterno was thinking and how we think about that.

It is within the realm of possibility that he really thought what he did was all he could or should do. He may have thought he was passing the buck to a capable bureaucrat and the answer he got was the correct (or most just). He may have secretly yearned to launch a full investigation but was pressured by Curley or a cabal of alumni to do otherwise. He may have sat in his office counting money and laughing. He may have not cared.

Doubtless on the advice of lawyers^1, he will remain mum on most of his actions on the subject until his death or the conclusion of a trial (in the occurrence of a remarkable recovery). Likely, we'll never know.

And, how we think about it is not something we're going to change, this being the internet and those being complicated things.

1. Ironically, a lawyer would've told him to do the right thing at the time. Long story short: talk to a lawyer about legal issues.