After whipping up excitement about a 'new kind of politics' during the Labour leadership election campaign this summer, Jeremy Corbyn set out a different way of running parliamentary opposition, but the looming vote on Syrian air strikes has exposed the difficulty of putting this into practice effectively.
Attitudes change as societies open up, and as economic, social and educational prosperity spread, but this happens differently in different places. It is legitimate to be appalled by barbaric practices from which ones own society has moved on, but it does not follow that one can bomb others into change.
We might tell Hilary Benn that a change of mind - even at this late hour - could change votes and prevent the terrible violence that we are about to unleash. Let's ask him, on behalf of all who are gravely at risk from our bombs - in Syria and here at home - to speak passionately alongside Jeremy Corbyn tomorrow. He might wish to tell us how a principled man came to change his mind.
Proof that the British political class hasn't learned anything after Iraq came with David Cameron's ludicrous assertion that there are 70,000 moderate rebels fighting in Syria. It was an outright fabrication to rank with Blair's sexed up dossier on Saddam's WMD, which the then prime minister asserted could be launched against Britain within 45 minutes.