In the politics of the People's Party (if we can still call it that) every promise is a pledge. It is part of the language. Let us have a look at Mr Gordon Brown's latest and most comprehensive pledge. It is not only to refrain from increasing income tax during the first two years of the next Labour government but also, if I understand him properly, to adhere to this government's spending plans.

Does this mean its plans at the time Mr Brown made his speech? Or when it ceases to hold office? I am not at all clear. There may turn out to be a substantial difference.

For since Mr Brown spoke, the Government has committed itself to a new royal yacht and to the establishment of cadet forces in our schools, though Mr John Major is trying to wriggle out of the latter as fast as he can. "No firm plans as yet ... but very good idea, oh yes ... teamwork ... leadership ... discipline": all qualities which, as Mr Tommy McAvoy pointed out at the most recent Prime Minister's Questions, are manifestly lacking in the present administration. Ms Myra Hindley is already to stay in jail for the rest of her life. It will be the revival of the Brownies next.

Indeed, we may expect a small stream of such announcements or "initiatives", as they are called these days, between now and the election. Their aims are to make the Government look good and to make the Opposition appear as if it does not support the week's good cause. Why Mr Tony Blair should connive in this, as to a certain extent he has over Britannia, escapes me.

Why should he help the Government at all? There is no reason I can see. On the contrary: he is Leader of Her Majesty's Loyal Opposition. This does not mean that he is under any obligation to promise to buy her a new boat. It is the beneficent phrase, coined by Charles James Fox, which partly explains why one lot of our politicians desist from executing the other lot, though the temptation must be strong at times. It is Mr Blair's task until the election - now predicted for late March or late April rather than for 1 May - to make life for Mr Major as difficult as he can. He should have said:

"Well, Mr Major, you are the Prime Minister, and you must do whatever you think is right. But you see, I am Leader of the Opposition, and I am sorry I cannot enter into any prior commitments, particularly where they involve the Exchequer. Thank you, Mr Major, and good day to you."

That, or something very like it, is what Bonar Law would have said to H H Asquith. It is hard to see why a Labour leader talking to a Conservative Prime Minister in 1997 finds it more difficult to be firm than a Conservative talking to a Liberal before 1914. But so it is.

Mr Michael Heseltine's projected commemoration of the millennium provides another illustration. Mr Heseltine now seems to have gone stark, raving bonkers, and is well up with Sir James Goldsmith in the Fruitcake Stakes. No matter. If Mr Heseltine were as sane as ... well, it is hard to come up with a politician but, say ... Lord Justice Scott, it would make no difference. Mr Blair and Dr Jack Cunningham had no business giving promises of any kind to him, as they appear to have done in a humming, hawing, "She didn't say yes, she didn't say no" kind of way.

They should have said that they had the widows and the orphans to consider first, not to mention (as listed in Luke xiv, 21) the poor, the maimed, the halt and the blind, and that they could not promise to expend the national revenue on a floating gin palace for persons who had done little enough to deserve the nation's gratitude in the recent past; the more so in view of Mr Brown's proposals for financial stringency.

There is an even more telling illustration of the feebleness of the Opposition. Mr Jack Straw is reported to be "having talks" with Mr Michael Howard about the future of the Police Bill. On Monday the Lords comprehensively defeated the Government. The moving force was the Liberal Democrat Lord Rodgers, aided by Lord Browne-Wilkinson and his legal colleagues and by most former Home Secretaries. Labour has played an ignominious role. Mr Straw has failed to expose Mr Howard's fallacy that, just because the police had been illegally breaking and entering for 25 years or so, the Bill was merely putting on a statutory footing a recognised practice. It was recognised only by the police. Otherwise it was unlawful unless authorised by a warrant.

Mr Straw has now belatedly settled for prior authorisation by some kind of silly quango. Lord Rodgers prefers a circuit judge, who is not really a proper judge at all but what Horace Rumpole calls a "circus judge". Mr Straw and the Liberal Democrats should unite behind a real High Court judge to provide prior authorisation. It is to his Liberal Democrat equivalent in the Commons, Mr Alex Carlile, that Mr Straw should be talking, not to Mr Howard. It is no part of Mr Straw's job to save the Police Bill or to make Mr Howard leader of his party after the election, though it is sometimes difficult to tell what Mr Straw imagines his job is.

I return to Mr Brown's pledge. He cannot be accused of feebleness. But he may be convicted of a worse crime: political stupidity. "Stupid" is not a word I like using. Mr Brown is clearly not a stupid man. But then, nor was Hugh Gaitskell. He was, if I may so put it, even less stupid than Mr Brown. And yet, during the 1959 election campaign, Gaitskell promised not to increase taxes. R H S Crossman noted in his diary for 5 October:

"Our initiative went at a tremendous pace until the morning when we read in the [Daily] Herald Hugh Gaitskell's income tax pledge. I should add that all of us on the [election] committee, without exception, were appalled at what we felt was a breach in Gaitskell's intellectual integrity. The last thing I would have expected from him, as an ex-Chancellor and an economist, was a commitment of this kind. Moreover, it wasn't very popular."

Labour would have lost that election anyway. But there was agreement that Gaitskell's declaration did not help and was, in modern terminology, a "gaffe". In 1992 John Smith went out of his way to follow the opposite course. At the beginning of the campaign the Shadow Chancellor presented his Shadow Budget, the spin doctors (then an infant profession) having hired the premises of an engineers' institution near Westminster whose 19th-century panelling lent a dignity appropriate to the occasion. After Smith's performance several acquaintances of mine, all earning well over pounds 22,000 a year - the cut-off or, rather, cut-in point for higher taxes - whipped out their pocket calculators, pressed a few buttons and announced that, if Labour attained office, they would be several thousand pounds a year worse off. Accordingly they intended to vote either Liberal Democrat or, for the first time in their lives, Conservative.

Mr Brown has not made Smith's mistake. He has not precisely made Gaitskell's either. Gaitskell promised that the party's plans would be paid for out of higher productivity and increased growth. Mr Brown has no plans, except those which have already been made by this government. Hence there is no need to increase taxes. What, therefore, is the point of a Labour government at all? I merely ask.