The 20th anniversary of the Rwandan genocide disinterred some terrible acts, by warlords and technocrats, and also raised the spectre of Tony Blair, normally so quiet that when you hear a rumour that he's moved to Jerusalem, it sounds atmospherically true, even while being manifestly not true.

On the Today programme he spoke of Rwanda and moved on to Syria, and how our failure to act on Assad would imperil us for years. In the Guardian he wrote about Rwanda ; and there are arguments one could have with him about his uncritical support for President Paul Kagame, a much more controversial figure than his version allows. There are debates to be had about Syria, and what these classic rationalisations premised on a counterfactual – we have to go in or we'll pay for it in the long run – actually mean. Do we have any reason to believe that interventions ever make us safer? Isn't the point of intervening against Assad not to save our own skins, but the people of Syria? But none of this came up, just as none of it ever comes up with Blair. The comments under his Guardian article were dominated not by Rwanda, but by the conviction that he is a war criminal. All anybody talks to him about is Iraq. He has no legacy apart from that war.

Blair left a blueprint for social democratic government; it wasn't perfect and some of it was disastrous. But we can't even see it because it has been obliterated by the bloodshed of the Iraq war. Even to say that "other things happened during the Labour term besides a war many of us did not agree with" is seen as disrespectful. We can't get over Iraq; only Iraq decides when Iraq is over. But this is completely silencing the left: it is ensuring that no stout defence can be made of those years: it is allowing the trope of "the mess they made" to become the truth; and it is preventing any coherent articulation that politics can be better than either "Tory" or "Tory-lite".

Many of the things the Labour party says now are laudable, and true: it is true that there are good capitalists and bad ones; it is true that global markets often look like a race to the bottom, but we don't have to just put up with it; it is true that regional regeneration is the key to a prosperous middle class and probably the partial answer to the housing crisis. But what Labour cannot make from these ideas is a solid, progressive identity, carving policies for people with ambitions beyond money, desires beyond their own front doors, and questions besides "What's the cheapest?". That identity is only possible if they are prepared to discuss their past.

Even though this starts with Blair, and how we understand his legacy, it does not end with him. The party itself has had its voice strangled, not by its collusion in voting for the war (this doesn't trouble any Conservative that I can think of), but by its inability to reach an accommodation afterwards. In the party they may mumble about why they voted the way they did, but generally speaking they have allowed Blair to become a pariah – and this leaves them unable to celebrate his achievements, incapable of examining what didn't go to plan. It leaves them without any pride in more than a decade of Labour government. Just about the only thing you hear being praised is Gordon Brown's swift and decisive action in bailing out the banks. Of all the decisions, we find the one that actually could have used a bit more thought – that actually did cost more than we could afford, that actually might have been more reckless than courageous – is the one we all feel so comfortable about.

The fact is, the national minimum wage that Blair fought for was a good thing. It isn't high enough; enforcement isn't strong enough; there are too many loopholes – but where do you think we'd be without that? Who in this government can you see fighting for the employee against the employer? When Blair came in, there were 3 million pensioners living in poverty; when he left it was 2 million. We have these arguments now about whether baby boomers stole everything because someone put selfishness powder in their milk supply, But it's preposterous to see that change as a generation war. This was a genuine attempt to tackle poverty, which happened to centre on pensioners because they were often poor, the fact that there are some rich ones notwithstanding.

The fight against child poverty was enshrined in law under the Blair government; I saw it as an attempt to avoid looking at the systemic causes of poverty, by sticking poverty in shorts and calling it cute. But I recognise, at least, that it's better to care about poor children than it is to recast their situation as the result of their parents' fecklessness. There is space between "Blair wasn't ideological enough" and "politicians are all the same".

Every hospital A&E was modernised or replaced in the Labour years; yes, they brought in that weak market system I think was needless – but carving the whole thing up and selling it to Tory donors? While your own MPs buy shares in donors' companies? Can we just take a second to consider how unthinkable that would have been from Blair's new cohort? Not because they didn't want the headlines, but because they genuinely valued the NHS, financially and morally.

Can you imagine Northern Ireland's Good Friday agreement coming out of this coalition, with its ramshackle headline grabs and constant backbench rebellions, the chaotic, directionless jerk of its agenda, like a rat on amphetamines? Its leaders just wouldn't have the meticulousness, the patience, or the breathing space to do anything that didn't score an immediate point.

Did New Labour spend too much on social security? No, it didn't spend enough (an argument for another day). But none of these conversations can even begin until we stop calling Tony Blair a war criminal. Maybe that sounds like dishonouring the dead; but what kind of wolves are we leaving in charge, while we nurse this hostile "honour"?