It's quite simple: if someone makes a financial transaction in a business manner (such as speculating on shares or currencies) the tax payer takes back 0.05% as a "Robin Hood" fee. This money is then used to help the poor, set up social systems, and fight climate change - in Ireland and abroad.
It's a tiny fee to charge and is not charged to individuals who are simply buying holiday currency or buying a few shares as a college fund for the kids.
With the amount of financial transactions going on in Ireland (in the IFSC, for example), and with us being the "Wild West of European Finance", then there is potential for huge gains.
We DO NOT propose a tax on the profits of banks, as banks are liable to make losses, rather we propose a tax on financial transactions, as this means it's only people/businesses wth money already who are affected. And we're only asking for 0.05% (that's only 5 cents in every €100 - surely this is an affordable tax!).
Basically, we take (a small bit) from the rich and give it to the poor. It's not radical, it's simple - and it's the moral thing to do.