From the banished Tory fringe comes a familiar claim in the ''Scottish'' Daily Mail (where else?). Gerald Warner, the right-wing pundit with a talent for entertaining polemic, writes that the Scots ''are not rich enough to go it alone without a massive reduction in living standards for generations''.

Gerald's is not a popular voice these days. Usually he proclaims views which were rubbished by the electorate twice within five months last year, yet he does us a service. In that one sentence he encapsulates the fears, justified or not, of a great many Scots - fears which go to the heart of Labour's battle with the SNP.

While Gerald was opining, the new pro-SNP Business for Scotland group - nicknamed Millionaires for Independence - was producing its first periodical in which David McCarthy, a former member of the Council of CBI Scotland, argues: ''Scotland's productivity in manufactured exports is over 50% higher than the rest of the UK - as an independent country (sic) Scotland is wealthier than New Zealand or Finland or Austria - all of which are small countries with strong and prosperous economies.''

One of those two gentlemen must be wrong but I suspect that in all the party bickering and mutual abuse we will not easily discover which. The trouble with Scottish politics these days is that it is being conducted by megaphone via spin doctors and press releases, a process which does little for objectivity. Consensus politics this is not.

Some facts might assist. In the run-up to the referendum last year we kept hearing from big business interests how investment in Scotland would collapse at the prospect of a Scottish Parliament and how the moneymen would scamper to the security of Carlisle. But what happened? I asked Scottish Enterprise for an assessment of investment in Scotland since the people voted overwhelmingly for Home Rule. Back came a fax listing 28 companies, some of them big international players like BT and Thomas Cook, the Delta Group of Taiwan, IBM at Greenock, Tasco Europe, Cadence Design Systems, to name just a few. All are in the business of investing in Scotland either through new plants or expansion of existing operations.

We can never be sure about the claims these companies make about employment but we can safely assume the jobs involved will run to several thousand (Cadence alone is talking of almost 2000 over seven years). There will be other investors, of course, which we don't know about because they have pressed ahead without involving Scottish Enterprise or Locate in Scotland or the Government and don't show up yet in statistics.

In fairness we must also ask how many companies have concluded that the Scottish Parliament is a disaster waiting to happen and, as predicted, have taken the chicken run down the M74.

The answer is, er, none. Those who have packed up or postponed developments have done so for reasons unconnected with Scottish politics.

The obvious question then arises: what would happen if the SNP got its way sooner or later and Home Rule became independence? Inevitably we would hear the same arguments from a few business pessimists and Gerald in the Daily Mail. But I strongly suspect that the business world would continue to operate as if little had changed.

This is a debate which will run until there is an independence referendum to clear the air but that is a prospect probably still years away. Indeed the question might never be resolved in the lifetime of many of us if that referendum was to be held within five years and the SNP lost it.

For the moment we should let the political argument about Scotland's economic future benefit from the oxygen of objectivity and not just from ingrained prejudice and excessively wishful thinking on both sides.

A dismal aspect of the current national debate is the very deep animus and meanness of spirit which Labour and the SNP hold for one another. Last week both parties routinely swopped cheap abuse and blatantly misrepresented each other's true agenda.

In so many words Labour said the SNP were bogus patriots bent on deliberately wrecking the Scottish Parliament and economy which we all know is untrue, because that would patently lose the Nationalists all credibility as a serious party seeking to govern.

Likewise the SNP dismissed Scottish Labour Ministers as craven careerists parroting a script dictated by their London masters - when rather the opposite is true. The fact is that today's Scottish Labour Ministers, who helped save the British Labour party from oblivion during the long Tory years, are the butt of continuing complaint in London that in government they operate as an unduly influential, pro-Scottish mafia.

Scotland deserves a political debate which transcends electoral deceit and the routine falsification of opponents' intentions. Our politicians should remember their grand proclamations about new standards in Scottish politics, but I'll not hold my breath.