Fantastic piece in the Guardian comment by Bryan Gould, which comes the closest to nailing the demented mix of hubris and boggle-eyed manichaen certainty behind Blair’s commitment to the Iraq war:
Prime ministers who serve a reasonable length of time are always in danger of succumbing to what I call “prime ministerial syndrome” – the belief that, after years of acolytes hanging on their every word, they are infallible. Tony Blair was temperamentally peculiarly susceptible to this condition, exacerbated in his case by his extraordinary ability at that time to persuade the British people of anything he chose. It is easy to see how he came to believe that whether or not the stated reasons for the Iraq invasion were true simply did not matter; the fact that he himself supported the venture was enough.
Why did he support it? He had by this time convinced himself that he was a world statesman, equipped to partner George Bush in a duumvirate which would re-shape the world. Underpinned by a hitherto undeclared religious conviction, he increasingly saw the world in terms of absolutes – good and evil, right and wrong. Like the American conservatives, but for moral and religious reasons rather than misplaced ideological opportunism, he could not resist the chance to strike a blow not only for enlightenment but for his own destiny.