There is a moral case - to give the inspectors the time they need

Mr Blair must persuade the US, as he has manfully before, of the need for unity on the UN Security Council

Morality, as a defensive Downing Street found yesterday, can cut both ways in politics. On Saturday, Tony Blair said in Glasgow that the moral case for war was the "moral case for removing Saddam". It wasn't, he hastened to add, the reason for acting – that was what UN resolution 1441 had to say about weapons of mass destruction. But it was the reason "why if we do have to act, we should do it with a clear conscience". Which led to yesterday's questions about whether Saddam would be allowed to stay in power if he did disarm. To which the answer is, of course, "Yes". So regime change, as the motive for war, creeps rather unconvincingly back in its box for the time being.

On one level, there is less to this than meets the eye. Indeed it gets quite close, allowing for the glaring differences, to why the dominant chunk of the Labour Party – minus, as he frankly recalled in the Glasgow conference's most persuasive platform speech, a now repentant John Prescott – supported the Falklands War. If General Galtieri hadn't been a fascist dictator, much more of the left might have been inclined to leave the islands to the Argentinians. On the other hand, they didn't expect the war necessarily to unseat the regime in Buenos Aires.

But it does illustrate the difficulties in simple appeals to morality in the argument about war in Iraq. One of the most striking features of that argument is the moral absolutism which is being waged on either side. Many, if not most, who demonstrated in hugely impressive numbers in London on Saturday are convinced that war against Iraq would be morally wrong. Mr Blair appears to be equally sure that it would be morally right.

There are problems with this absolutism on both sides of the argument. Aside from those marchers who hold the morally wholly respectable position of pacifism, a large number would probably say that Hans Blix should be left to get on with the job of tracking down whatever biological, chemical and proto-nuclear weaponry Saddam may or may not still have. Yet they still have to get round the fact – acknowledged by President Chirac in his current Time magazine interview – that the inspectors would not be there at all were it not for the threat of military action.

But moral absolutism carries, if anything, just as many dangers on the pro-war side of the argument. Tony Blair may well be right that resorting to morality is a necessary condition of challenging what he himself on Saturday called the "moral case against war". But it isn't sufficient. The argument that "my morality is righter than your morality" will always be an ultimately sterile one. Logical appeals to collective – in the widest and most global sense – and enlightened self-interest matter just as much in a mature democracy.

The first danger is that truth gets bent out of shape because it's seen as mattering less than the supposedly Higher Truth of the justice of the case. In his interview with The Independent yesterday, Menzies Campbell, the Liberal Democrat foreign affairs spokesman, referred to growing unease in the intelligence community about the propagandist use of its material. The most dispiriting intervention by the US Secretary of State Colin Powell in the past week, worse even than the UK Government's crass plagiarism of an obscure academic article, was his assertion that a Bin Laden tape, if that's what it was, demonstrated the "link" between al-Qa'ida and Saddam's regime. It did no such thing, and the argument that it did was based on a classic false syllogism: allies threaten war against Baghdad; Bin Laden seeks to exploit war against Iraq; ergo Bin Laden is in hock to Baghdad. This isn't treating the electorate – US or British – as grown-ups.

Any more than it is treating them as grown-ups to ignore some of the questions troubling a questioning electorate. Will war increase terrorism rather than diminish it? Will it hasten or delay a just peace in Israel-Palestine? Are Kurdish elements in the Iraqi National Congress right to fear that the US's still mist-shrouded plans for a post-Saddam Iraq will bypass the pledges on democracy? Will war necessarily make it easier to locate and destroy weapons of mass destruction?

The related problem of moral absolutism is that it oversimplifies the complexities that true diplomacy is built on in democratic countries. Even if there is a moral case for an eventual war, there is every bit as strong a moral case for doing everything humanly possible to prevent one. Equally, those around Mr Blair make a moral case that even if a second resolution is vetoed and the US and the UK act alone, they will still be acting morally by enforcing the authority of the UN. Maybe. But the political realities are quite different. Perhaps, as some around the Prime Minister assert, there is a larger silent block of Labour MPs who would be prepared to vote for war without explicit UN sanction than most estimates allow. But it doesn't alter the fact that the Government is right to be fearful of declaring war without a second resolution.

All of which points to Mr Blair bringing all his influence to bear on Washington in the time remaining. That time may be a little longer, and the influence a little greater, than some commentary allows. Hans Blix is indeed due to report again to the UN on 28 February. But technically that is a report on UN resolution 1284, the one that established an inspection process before Saddam admitted Mr Blix's team. He is not due to report on the progress on Resolution 1441 – and therefore on whether Saddam has demonstrated any more compliance – until 14 March.

Mr Blair should do everything he can to ensure that the crucial decisions are not taken until then. The benefit for the allies – including Washington – would be that the chances of securing unity on the Security Council would be maximised, since Mr Blix would have some of the time he evidently thinks he needs. The advantages for the cause of peace would be that the admittedly slender chance of Saddam climbing down – as several Arab countries devoutly want – would also be maximised. And it need not encourage Saddam to play games with the inspection process, provided the threat of military action remains ever-present.

Nor is it impossible to achieve, for all the growing impatience in Washington. Even the hawks in the US are nervous about a war without the UK at its side. Mr Blair is in a stronger position than the rather empty poodle metaphor allows, if he chooses to use it. He needs to persuade the US, as he has manfully persuaded them before, of the need for unity on the UN Security Council. He needs to try to elicit – and publicly re-transmit – some of the answers to the questions worrying a deeply uneasy electorate (and Saturday's demonstration should go a long way to persuading Washington how real those worries are). He needs, too, to press the US again on the need to revive an initiative in the Middle East peace process. All this he can do without forsaking his stance as the US's most faithful ally. And yes, the imperative that he does so is moral as well as political.

d.macintyre@independent.co.uk