The economic argument pertaining to nationalism is an interesting one. Not the most sensible one, just one of the most interesting.
It is interesting on a number of levels. It is an argument with few definitive facts to support it or to argue against it. The figures are part of a great unknown, and in the void supporters of both sides make their own facts up.
Take tax, for example. Some say that more tax is spent in Wales than is raised in Wales
However if you spend £100 on a new suite in a major store on Rhyl High Street, you pay about £14 in tax on it. That tax is not raised in Wales; it is raised in whatever part of England that the shop's accounting department happens to be located in. The assistant who serves you in the shop earns her income in Wales, with out any doubt, but her income tax is also paid in the English town that is home to her employer's accounting department - its all English tax. And when Wales gets that money, spent in Wales - earned in Wales, back; its English tax subsidising Wales!
Tax raising moves the other way too, some English money is taxed in Wales in a swings and roundabouts movement. But the figures to prove a tax and spend balance for Wales (or England) do not exist. So arguments for or against independence based on tax and spend are all just whistles for my side and not based on fact. The true figures aren't available. I know that I'm a miserable old cynic, but I suspect that if the true figures proved, beyond doubt, that Wales was a leach on the rest of the UK, that those figures would, somehow, be in the public domain!
The economic argument is also interesting because of the absolute tosh spouted by both sides of the economic argument. If Wales became independent tomorrow it wouldn't become an impoverished third world country, overnight, as some Unionists claim; but neither would it suddenly become the new Celtic Tiger economy that some nationalists claim.
The truth is that an Independent Wales' economy would remain at about the same level as it was on Independence Day for some time. If the economy improved or declined over time after independence would depend on how well the Welsh Government managed the economy. It would depend on the sort of Government that the People of Wales decide to elect.
However, whatever sort of government we elect, it would be a government that would be committed to try, at least, to govern the economy in a way that was beneficial to the Welsh economic interest, something that an Unionist British Government can never guarantee to do.
The most interesting thing about the economic argument however, is the way in which A Poor Welsh Economy is the main plank of the Unionists argument. Take away that plank and the Unionists have little else left to stand on, so Keeping Wales Poor is in the Unionists' best interest.
And if Keeping Wales Poor is in the Unionists best interest, opposing the Union, MUST be in Wales' best economic interest!