In first-year ordinary philosophy seminars, students used to debate the question of whether we can rely on the evidence of our senses to give us an accurate account of the real world.
Is this a real table before me, or am I just dreaming or imagining a table? I've been having similar problems with the referendum debate.
There was Alistair Darling, the former Chancellor and an ardent fiscal unionist, saying at the weekend: "Most people think the present settlement does need to change and my view is that any Parliament that can spend money but doesn't have the pain of raising it isn't satisfactory." Well, actually, most people in the Labour Party do not think the present settlement needs to change – at least not in the direction of fiscal autonomy, or devolution max, or federalism, or whatever you like to call it. Or so I thought.
I was under the impression that only relatively dissident figures like the former First Minister Henry McLeish, or the former Labour Minister Malcolm Chisholm had been talking about giving the Scottish Parliament the power, through income tax and other taxes, to raise the money it spends. But clearly I've been relying on my all too fallible senses here, and Mr Darling agreed with them all along.
Yet I could have sworn that the former Chancellor, like Gordon Brown and Ed Miliband, had rejected "fiscal freedom" as the SNP used to call it, on the grounds that giving Holyrood the power to raise the money it spends would effectively make Scotland independent. I was labouring under a delusion that Labour's Scottish leader, Johan Lamont, was mightily suspicious of devolution max, along with Labour MPs like Tom Harris, who only recently said: "Devo max is a nationalist ploy ...and an obvious bear trap."
This must have been in a parallel reality. Where I was in January when I thought I heard David Cameron quoted as saying that giving Scotland more fiscal powers (beyond those in the Scotland Bill) would be "incompatible with Scotland remaining in the UK". This was clearly the reverse of what the Prime Minister actually meant to say, which is that Scotland can have any powers it jolly well wants, just so long as it stays nominally in the United Kingdom. I must have similarly mis-perceived the Scottish Tory leader, Ruth Davidson, during the recent Tory leadership campaign when she rejected more powers for the Scottish Parliament on the grounds that "enough was enough" and that devolution max was pure nationalism. This was an another illusion created by those unreliable senses. Like the Prime Minister, she must also believe that more powers can be handed to Holyrood provided Scots vote no to independence.
Of course, opponents of independence are perfectly entitled to change their policies, to fudge and mudge, to triangulate and strangulate the meaning of Unionism. After all, that's what Alex Salmond has been doing with independence, which can mean anything from a "new United Kingdom" to Scotland "taking her seat in the United Nations". Some say that devolution max, if it happened, would be far too separatist for the SNP, who want to keep, variously, the Queen, the pound, the Bank of England, British bases, British passports, the consular corps and Rupert Murdoch.
However, the Nationalists have one big advantage: Mr Salmond, and I mean no unkind reference to the First Minister's girth. Independence means whatever Mr Salmond says it means, and he leads a party – and indeed much of the nation – that seems quite happy to leave it that way.
He will not only set the question on independence, he will tell us what it means, but only on a need to know basis. Somehow, people trust him.
The problem faced by the Unionist campaign thus far is that it lacks a proper leader, is intellectually confused, politically divided, widely mistrusted and fatally associated with a party – the Conservatives – which as we all know has fewer MPs in Scotland than giant pandas. Critics like the former Scottish Secretary Michael Forsyth say that Mr Cameron is only "playing into the SNP's hands" by offering more powers. They won't let up.
A worse problem for both Mr Cameron and Mr Darling is moral inconsistency. It is difficult to argue that the option they claim to favour, more powers, is the one that should not be put to the people in the referendum. Both are saying: "Trust us, vote no, and you'll get a Scottish Parliament with the powers you want." Clearly, they are under the delusion that Scots voters were born yesterday.
To be credible, the No campaign needs to say, first of all, where they stand on the Scotland Bill, which does not give Holyrood the power to raise the money it spends, or anything like it. Really, someone needs to put the Bill out of its misery because it has become an embarrassing irrelevance. To bridge the trust gap, Scots need to be assured, either that there will be a new Scotland Bill, that there will be a second referendum on new powers, or that it will be left to the Scottish Parliament to decide what constitutional arrangement is suitable for Scotland within the UK. Maybe this isn't enough.
The danger now for the Unionists is that Mr Salmond – following the lead set by Mr Darling and Mr Cameron – may offer a version of independence that is so close to devolution max that Scots vote for it out of spite at not seeing their favoured option on the ballot paper.
I'm beginning to think that this is a real possibility. The "social union" that Mr Salmond proposes for England and Scotland appeals to many Scots, who want economic autonomy but don't want to separate from their kith and kin.
If he were really sneaky, Mr Salmond could even offer a second referendum – as has been advocated by constitutionalists like Robert Hazell of the University of College London Devolution Unit – after the details of independence have been worked out. This would lower the stakes in the first ballot and allow Scots to vote in principle for independence, with a backstop if they didn't like the reality of it. It would be a gamble – but Mr Salmond is the ultimate political gambler.
Now, where is that damned table?