What's the lesson to be learned? Modesty. Before initiating a war of choice -- and Vietnam and Iraq both qualify -- define the goal with honesty and precision, then analyze what means will be needed to achieve it. Be certain you really understand the society you propose to transform. And never gamble that the political solution to such an adventure will somehow materialize after the military operation has begun. Without a plausible political plan and strong local support at the outset, military operations alone are unlikely to produce success.If this is what the liberal hawks think went wrong with Iraq -- Bush didn't study enough? -- then we are truly doomed. Bush, Rumsfeld, and Wolfowitz thought they had studies the goal with honesty and precision, as Kaiser wishes. It just turns out they were wrong. Why? Because they were, in this context, revolutionaries. They ignored any and all historical data or judgment, because they believed it was irrelevant to this endeavour.
Moreover, the kind of knowledge Kaiser wants governments to have before they engage in "wars of choice" is not reliably available. How exact do you think US knowledge of Iraqi tribal structures was pre-2003? How good do you think it is today? My bet is not very, or not nearly enough. Kaiser's editor gave his column the header "Trapped by Hubris, again" but it's clear Kaiser doesn't understand what the Hubris was.
Hubris isn't when you consciously act in the absence of knowledge. That's just plain old dumb. Hubris is acting with certainty when your knowledge is flawed, or non-existent. Kaiser's answer to the hubris of Iraq is "be more certain", but that's just a recipe for further disasters. The right answer to hubris is humility, not more certainty. Start from the position that yes, you will fuck up, and yes, your knowledge is bound to be incomplete. Most importantly, governments need to understand that some tasks are simply beyond them, even the most powerful ones.
The lesson of Iraq (or Vietnam) is not "be smarter, then invade". It's "be smarter, don't invade."