Every president has a doctrine of some sort named after him, for the way he handles certain problems in his republic. In Bush's case, he has the unenviable problem of dealing with post-coldwar nuclear politics. Now that there is no longer a balance between the two major forces of nuclear power, proliferation is spreading, and there is a split between the major methods used to fix these problems.
One method is to find a way to get along with your neighbors. The other is to dominate them. While the first creates short term disadvantages, such as having to buy your oil at the same rates other nations have to pay, it doesn't have the major long term disadvantages of the second option, in which muffled resentments worldwide guarantee an unending stream of terrorism and rebellion against the more fortunate in the dominating nation.
The Bush doctrine is of the latter category, and at its core is an attempt to coerce others through fear. "We won't hestitate to make a first strike if we think you're a terrorist nation, or harboring terrorists," he says, opening up the possibility of a first strike on anyone -- terrorist bodies can always be found in the ashes. And since his document addresses general military solutions, it is not long before this first strike will be extended to any country other than the US, Israel or NATO which develops nuclear weapons.
The consequence of this is that nuclear diplomacy on the national level is dead, and politics is now returning to the organizational status of tribalism. What first brought about terrorism was the need to be exempt from retaliation upon a national base, and now that that threat is raised, terrorists will only be outlaws in other countries. And now that they know retaliation will come swiftly, and possibly in nuclear form, they will not bother to announce their politics or even give any information before attacking. Since all of America's cards are on the table, they know what must be evaded. Thus the Bush doctrine will not prevent terrorism, nor does it hope to.
It hopes to limit the ability for countries to mount dissent against the USA. If they are unable to tell when an attack will come if they step out and become criticial of the USA, thus becoming possible "terrorist nations," they're going to do what Iraq and others may be doing: sponsor smaller, nationless groups who take a "multicultural" approach toward tearing down the USA. With no target toward which to retaliate, the USA will then lose its detente factor of terror versus terrorists.
When that happens, the Bush doctrine will come into play for what it really is, a law which benefits from selective enforcement. Those who need to be conquered for our global imperialist neoliberal ambitions will be, with the words "terrorist" and "evil" on the lips of our leaders. And soon, in the name of being "good," a totalitarian world empire will crush all dissent in the name of convenience.