In the realm of foreign policy, "Ideology" is getting a bad name. "Pragmatism" is, apparently, all the rage. Problem is we aren't being careful with our terms. (For a primer on the debate, see Chris Hayes' meditation on the subject, as well as this very interesting and provocative post from Glenn Greenwald). We tend to dislike ideology when it leads to bad outcomes. We tend to be much more forgiving when it leads to good ones. The problem with the last 8 years of Bushism is that ideology became dangerous. That doesn't mean ideology always is. It does mean that ideology in the wrong hands, and without a healthy dose of empiricism, can be.
When we say Bush's "ideology" failed, there are a variety of things that are implied, but aren't necessarily clear. The major objection to the Bush foreign policy approach was that it held to a fundamental belief in the primacy - and transformative nature - of military force. The military, if used in certain ways, could and would solve certain problems. This is wrong. An ideology based on this assumption is dangerous, because it attributes qualities to military force that military force, in reality, does not actually possess.
The second supposed "cornerstone" of Bushism was a fundamental belief that democracy either was or could be an antidote to political violence and terrorism. More broadly, democracy promotion would begin to address the root causes of so many of the Middle East's recurring problems. The logic was intuitive - that as long as Arabs were denied outlets to express their grievances through legitimate, democratic means, they would be more likely to resort to violent methods (in the absence of nonviolent ones). This is not, in fact, untrue. There is a growing literature which does, indeed, suggest a causal link between lack of democracy and political violence. I won't get into that now though.
In any case, when we say that Bush's "freedom agenda" failed, we can mean one of three things:
1) It failed because the basic premise was wrong. This would indicate a flaw in ideology.
2) It failed because means were not effectively matched with ends. This would indicate a flaw in execution.
3) It failed because it was never, in reality, attempted. This would indicate a different kind of flaw. It would render the assessment of failure essentially moot or irrelevant.
I would say that the freedom agenda failed mostly because of #3 and partly because of #2. The Bush administration never actually tried, in any sustained way, to support Middle East democracy (there was a brief period in 2004-5 where there was some pressure on Arab regimes, but that posture was quickly reversed in late 2005 when Islamists started doing quite well in elections in Egypt and Palestine). Too much of a good thing (in this case, democracy), apparently, was judged to be bad. So, of course, the freedom agenda failed. We all lost faith in it too quickly because what we thought was a good policy - supporting elections - led to what we thought was a bad outcome (this is also known as the "Islamist dilemma").
The execution problem is almost just as important. The Bush administration had a foreign policy objective - the democratization of the Middle East. It then decided that invading a dictatorship would be an effective means for doing so. Needless to say, this was a mistake of very large proportions. So much of the democracy agenda was dependent on Iraq being a relatively quick success, and when it wasn't, the agenda began to suffer elsewhere in the region. Moreover, as Iraq began to deteriorate (and Iran began to rise), the importance of having authoritarian Arab regimes on our side became more important.
In any case, the experience of the last 8 years tells us little about the broader notion of supporting democracy in what remains the most undemocratic region in the world. We are also not being clear enough about means or ends. It is possible to be pragmatic in the pursuit of ideological goals. It is possibly to be ideological in the pursuit of ideological goals. The latter is not usually good. The former can be good, particularly when you agree with the ideological goals being pursued.