I'm nervous as I watch Mr Brown perform his tricky balancing act

How does it come about that you can find people who think the Government is not spending enough on the public sector?

Lord Macaulay summed it up in his poem about Horatius at the bridge. You'll remember that Lars Porsenna of Clusium, king of the Etruscans, marched on Rome to reinstall his deposed fellow king, Tarquin. Rome wasn't the power then that it later became, and guarding the vital bridge over the Tiber from Porsenna and his array were just three Romans, a chap called Horatius and two pals. Understandably the Etruscans pushed on, only for those who went first to discover that Horatius et al were no push-overs. As the bodies piled up at the front, the blokes in the rear became restive at the delay, so that (as Macaulay put it) "those behind cried 'Forward!' And those before cried 'Back!' "

In the Etruscans' case there was some excuse for this completely different understanding by people in the same army of the situation they were facing. There were no mobile phones in those days, so Aruns of Volsinium couldn't inform the rearguard of what was going on, before he got smote ("smitten" somehow seems wrong).

It is less easy to understand, though, why today people in the same political party, or observing or commentating on the same set of events, should have such a different idea of what is going on before their eyes. How does it come about that you can find, in any paper, on any website, in any institution – simultaneously – people who think that the Government is not spending anything like enough on the public sector, and people who believe that the Chancellor is gambling the future of the nation by spending far too much? Do these folk never talk to one another?

There are plenty of critics, including letter writers to this newspaper, who argue that more should be spent even than is now planned. This I take to be the logic of arguing that the firefighters should be paid a very large increase without bothering too much with productivity. Or that teachers in London must get much higher weighting allowances. Or that lecturers in universities deserve (as they do) substantially enhanced pay. Or that all students should have their fees paid for them by the state.

Meanwhile, we discovered on Tuesday that the Chancellor's forecasts had been too rosy and needed to be revised. But if Mr Brown had been over-optimistic last year, it was obviously not for the sake of cutting taxation. The purpose of that optimism was to convince himself and us that we could indeed afford to continue with a substantial increase in funding for public services. As the position worsened, we were asked to pay more in National Insurance contributions from next year, and the Chancellor announced an intention to increase borrowing by a large amount.

I like Mr Brown. He always said that one should pay back debt during the up-swing of an economic cycle, and borrow again (if one had to) during the lean times. This makes sense to me as a kind of modern version of Joseph's grain-storing in the Bible. It means, apart from anything else, that you don't add to a potential recession by putting public employees out of work, or cutting back on capital projects that employ many in the private sector.

But that doesn't mean that I'm not nervous. I certainly am. Standing close to the bridge, I think I can see the glint of the swords and hear the turbulent waters below. I wonder whether the Brown gamble is going to come off. If a there is a war that isn't easily won, or if there isn't a European recovery, will we face higher taxes or cuts in elf and educashun?

And then, right in the middle of this, we have several public-sector unions moaning that the Government never does anything for their members, and that unless it does they will have no option but to bugger up everybody else's life. It's not just the FBU, but when I heard one firefighter yesterday talk about how he and his colleagues had been badly treated for 20 years, I asked him, via the radio and the intervening space, why he hadn't gone on strike during one of those Tory years? Why did he wait until a government came along that actually did... Need I continue? We know the answer. That is the answer.

Old John Monks at the TUC – unable for some reason to tell his members straight that the Government has gambled big on a commitment to public services – then says that trade unionists should get behind the FBU. No, John, the FBU should go back to work. And I would like to hear Mr Monks (for whom I have a great deal of respect, as it happens) on the subject of Bob Crow and the forthcoming RMT strike ballot, to be held because of the possibility of the disciplining of drivers who fail to turn up for work because they have decided (whatever the Health and Safety Executive says) that they are somehow not safe enough to drive to work the people who pay their wages.

What is going on at the moment, whether it be with the teachers or the firefighters, is a semi-conscious attempt to coerce the service providers into funnelling the extra government investment in particular directions. Give it to us or we'll do you over. Then, when challenged on the implicit unfairness of this to other workers, the strikers or the unions will almost always declare that they are in favour of everybody getting exactly what they want. They are nothing if not generous.

I don't mean by this that there aren't good causes out there, particularly among the lowest paid and in the universities. A large proportion of the million NHS staff who may soon get substantial rises (linked, we are assured, to modernisation) are in the low-pay category. And yesterday we heard the Education Secretary, Charles Clarke, agreeing that the university system had been allowed to "drift for 35 years".

But what are we to do? Let the situation in universities worsen, until some begin to close down? Borrow even more (some estimate over £5bn) to fund a proper settlement in higher education? That hardly seems prudent. Charge students top-up fees, so that they effectively subsidise top-class research in the best universities? Or maybe take it from the firefighters, the health workers and the teachers? Enter, at this point (from the back) young William Straw, student leader, who says pretty much what I'd have said 25 years ago, which is that we should fund it through taxation. And unless he has some candidates for public-sector cuts, Jack's boy is advocating tax rises on the back of the NIC hike.

And now I am going to break the cardinal rule of columnising. I really don't know what the Government should do about universities. I do not find any of the options attractive. I don't think we can borrow more, I don't think we can leave our universities to rot, I don't think the public will wear a general tax rise (forget the seductive but false idea of raising enough from "taxing the rich"), I don't think that schools and hospitals should have their budgets cut, and I don't like the idea of top-up fees very much. As Macaulay said, "backward now and forward, wavers the deep array". Those that don't waver, it seems to me, are either very clever, or very, very stupid.

David.Aaronovitch@btinternet.com