I suggest that Blair shouldn't pin his hopes on getting a fair hearing, or an honest debate, from the left:
Liberal-left types are of course fully aware of the “complexity” of the decisions that were taken, and are still being taken, over when and how the West should intervene to combat rogues states and terrorists. They just like to pretend that such complexities don’t exist; that there are no difficult decisions, and no consequences for doing what makes you popular, rather than what’s right. And hypotheticals only work one way, so opponents of intervention will ask “Would you do it again?” but never “What if we hadn’t done it?” or “What should be done next time?” The left has a vivid imagination when it comes to threats to liberty posed by conservative governments, or threats to the planet caused by global warming, but is unwilling to imagine what might have transpired in the Middle East had Saddam remained in power, or the consequences of Iran getting nuclear weapons.Blair points out that the West will soon face a similar dilemma over Iran's determination to acquire nuclear weapons. Don't expect the left to engage in that debate with any more honesty or decency than they displayed over Iraq.
The left can’t accept that, although they disagree with their opponents, those opponents might have a valid point, or might be motivated by something other than sinister aims. The arguments Blair advances are ones that are seldom aired outside conservative media outlets or in speeches by Dick Cheney and John Bolton. Blair has a platform that is rarely afforded to advocates of military action against Islamic extremists and their state sponsors, and his position flies in the face of the liberal-left narrative, which is why they hate him.