Martin cites James Surowiecki's book The Wisdom of Crowds as evidence for the reason Blair (and most of the Conservative party) parted company with UK public opinion over this decision:
Blair had an excess of information, while the crowd, deprived of all the intelligence reports he was privy to, had been forced to see the salient features of the war, and had instinctively judged it to be 'wrong'.
Martin is right about the crowd, but he's wrong about Blair.
There is no such thing as too much information.
There is such a thing as too little filtering. Information overload is filter failure. That's where Blair went wrong, in being unable to pick out the signal from the noise. Earlier this week a colleague of mine was shocked when they saw how many RSS feeds I subscribed to in Google Reader. We were discussing the relative merits of Netvibes (which is great for displaying but not crunching information) and dedicated RSS readers. After I deep sigh, I had to have the filter on the way out conversation. Blair didn't filter enough, and he probably had too many people filtering on the way in. The one thing he didn't have was too much information (such as, what the consequences of his decision would be).
There is no such thing as too much information. There is such a thing as bad filtering. That's why social networks such as Facebook and Twitter are the most important outcome of the Web 2.0 era. They are glorious noise. The crowd speaks to the crowd, and the crowd listens, but more importantly, the crowd filters.
Send me some noise.