Kay notes the Iraqi invasion of 2003, and assumes without arguement it has been a failure. I agree on that, though the reason I have is probably different than for most commenters, and I think the why matters. Anyway, he notes he didn't know beforehand it was a failure, but:
I believe the right way to have formed an opinion would have been to say "I do not trust the judgment of the people [Bush and Cheney] who are making this decision or their ability to handle the consequences." That would have led to the right conclusion, and for the right reason.
As a 'right reason' it seems pure hindsight, because he gives absolutely no reason to not trust Bush and Cheney. He has other such practical examples of obliquity, which come off a lot like the derided objective to 'maximize shareholder value', an objective without much use because its easy ex post, but impossibly unspecific ex ante. Asking the right questions doesn't mean you are going to get good answers, which I guess highlights his main point, that good solutions are indirect.