Were I to get a look at George W. Bush's bookshelf, I'd wager that I'd see several Tom Clancy novels placed prominently. His dad's tenure in the White House notwithstanding, I'd be willing to bet that Bush's conception of how to govern came in large part from reading Clancy's crude portrayals of the office (particularly in the novels in which Jack Ryan is president). Clancy seems just about right for Bush, the novels are verbose but trenchant and offer the illusion of being middlebrow.
Every major presidential choice in a Clancy novel is inevitably framed as being a question of morality or of courage. That more or less describes how Bush approaches major presidential questions - so much so that his advisors usually frame choices as being those between courage and cowardice - and guess what Bush always chooses.
In Clancy novels, the president always draws the line, never backs down, and revenge is always to be had. Villains do not get away. Technological solutions work in concert with with covert action (the ubiquitous Mr. Clark character). Afghanistan had the hallmarks of a Clancy novel: precision bombing in concert with special forces action. No doubt he thought Iraq would unfold similarly. No Clancy novel has ever featured a counterinsurgency campaign (Clear and Present Danger does have some jungle fighting, but American losses occur because of betrayal, not the sheer messiness of jungle warfare). In Clancy-world technology and American resolve always trump the nefarious plans of the evildoers. One never sees incompetence on the Rumsfeld or Tommy Franks level.
This is why all he seems to say about Iraq is "Stay the course." Another administration might have at least reached the point where they were willing to broadly revise strategy. Bush, like President Jack Ryan, sees every question as being primarily one about resolve and courage. Pragmatism and strategy - the conception that discretion might be the better part of honor - these things can't enter into the equation.
None of this is to divest Bush of more craven motives, but to propose one theory about where his simplistic conceptions about leadership might have originated. We do know that he's a big fan of Michael Crichton - especially Crichton's absurd ideas about global warming. It wouldn't be surprising if his model president turns out to be not Ronald Reagan but Jack Ryan.