THERE may come a time when this week's Budget statement from the Chancellor will be about as relevant to Scotland as a speech from the head of the European Central Bank.

Important, certainly, but secondary to the Scottish budget in Holyrood, which will set income tax, corporation tax, excise duty etc. If the supporters of devolution plus have their way, this might even be the case if Scotland votes No in the independence referendum in 2014. But the truth is that speeches by the Chancellor of the Exchequer are already becoming divorced from Scottish economic realities.

This is most obvious in the row over the 50p tax band, which it is claimed is discouraging investment, forcing tax-harassed businessmen to emigrate and encouraging wealth-creators to sit on their hands instead of investing for jobs. All highly questionable assumptions, especially in Scotland where very few people outside banking earn anything near the £150,000 at which the 50p rate kicks in. Scotland is a low-wage economy where people somehow muddle along on remuneration the London elite wouldn't get out of bed for. We also have a low-wage politics, with a presumption that extremes of wealth are socially divisive and economically damaging.

That's how we like to think of ourselves. At last weekend's Sunday Herald Independence Debate at the Aye Write! festival, one thing the politically diverse audience agreed on was that an independent Scotland should make welfare, poverty and education the priority. But is this naive? Are we right to assume a Scottish parliament with economic powers would act in the interest of the many and not the few? What guarantee is there that it won't be captured by the powerful commercial lobbies that have captured Westminster governments of left and right for 30 years?

The first budget of an independent Scotland will, of course, be a budget for jobs – but whose jobs? If it is an SNP government, the first act will probably be to slash corporation tax to encourage business investment. There will be pressure from small and medium enterprises for tax incentives to help them take on new staff. There will also be a strong lobby against increasing income tax, or arguing for it to be cut, to encourage wealthy people to come to Scotland. For if it is accepted that cutting corporation tax is good for jobs because it encourages private firms to invest here, won't the same argument apply to entrepreneurs? Many of the newly independent countries of Eastern Europe – Slovakia, Lithuania, Estonia – have introduced flat taxes of around 25%.

The Irish neo-liberal experiment ended in tears after the property bubble burst. This is what happens when you cut taxes too much, too fast. Wealthy people don't spend their extra money, at least not in the way you or I do, on commodities. They pile their cash into assets, which makes things like property increase rapidly in price. Asset inflation leads to boom and bust.

We wouldn't make the same mistake, would we? Actually, I think it is almost inevitable we would. Before the bank crash, Scotland was heading in exactly that direction, with the support of the First Minister.

OK – I'm not being entirely fair here. No First Minister could afford to alienate such an important sector of the Scottish economy, employing 100,000 people, and neither of Salmond's Labour predecessors did any different. "The Royal Bank of Scotland," Jack McConnell said in 2006, "is a strong example to all Scottish companies of what can be achieved by increasing their involvement in the global marketplace." Well yes, if they want to lose hundreds of billions of pounds.

But I say again, what makes us think a Scottish chancellor would be better at resisting the power of organised money? At Edinburgh airport, you could still be forgiven for thinking you are entering a country called RBS, so ubiquitous is the branding. Do we really think politicians in Holyrood can challenge one of the world's biggest banks which, even now, has a balance sheet 10 times the size of the Scottish budget?

We need to look at these questions now because, whatever happens in 2014, the Scottish Parliament is going to have a lot more economic powers, and these will attract the single-minded attention of "wealth-creators". The SNP might even split between Celtic neo-liberals and social democrats. Left-wingers such as Deputy First Minister Nicola Sturgeon see independence as a way to eradicate poverty, as she made clear in her conference speech. But Education Minister Mike Russell had a very different vision when he was out of parliament. In his 2006 book, Grasping The Thistle, he called for flat taxes, privatisation of hospitals and the virtual dismantling of the welfare state. He's changed his tune since, but he could easily change it back again.

Most SNP politicians are sincere social democrats who want to see Scotland emulate prosperous Scandinavian countries like Denmark, Sweden and Finland. But Sweden, remember, has turned its back on democratic socialism. The pressure from business and financial interest on government is immense. Look how rapidly the UK Coalition abandoned plans to discipline the financial services industry and turned to cutting its taxes. No-one talks about breaking up the big banks any more. The Liberal Democrats have abandoned just about everything they stood for and have ended up supporting £9000 tuition fees and draconian welfare spending cuts.

Of course, Scotland is different. There is no significant Conservative vote; inequalities of wealth are much less than in England; and there is greater social solidarity. Perhaps Scotland's small size will help insulate it from the harsh logic of the free market. On the other hand, an independent government might see no alternative to deregulation and low taxation in attracting jobs to pay for the loss of the Barnett Formula. The SNP is already a low-tax party, despite its social ideals.

We need to have these debates now, before any decision over independence. Scotland doesn't want to awake from the euphoria of the referendum to a bath in the ice-cold waters of economic reality.