Things can go down as well as up

Given the debate about whether there should be a review on the level of powers enjoyed by the devolved administration in Scotland one thing has been bugging me.  I had dinner with a cousin of mine and his parents last l week.  Their home is in St Andrews and my cousin is Scottish.  I was arguing against further changes in tax changing policy.  He was speaking powerfully in favour.  I've just been listening to the news on the BBC who speak of "new tax raising powers."  But that's not what the legislation said.  That speaks of tax variation powers.  In other words the tax rate could go up in Scotland versus the rest of the UK or, crucially, they could go down.  Why does everyone seem to assume that taxes always have to go up? So I reckon my cousin is right.  Give Scotland more power of variation on tax and let them show the economic benefits of lower rates of tax.