I'm late to this discussion but I can not see how anyone can argue that not paying tax or fraudulently claiming social welfare or other state benefits to which you are entitled is anything other than stealing, and stealing from your fellow citizens at that.
The use that tax money is put to is a different issue. One of the few benefits of the economic crisis is that the public and the media is putting far more pressure on government and public service to be fully accountable in relation to what they are spending and why and to cut out out wasteful and excessive expenditure. As a taxpayer and civil servant, I am delighted about this. Lets hope that this culture of demanding accountability remains if and when the economy ever gets up off its feet again.
Its a pretty simple equation - being a citizen entails rights and responsibilities. Rights to basic services, an efficient public service, decent health care and education, democratic accountability. A responsibility to obey the law (including paying tax) and register protest through democratic means (i,e, if the government is crap, get involved, use the media and the democratic process to get rid of them, don't just sit around whinging about TDs expenses and use their supposed venality as an excuse for undermining and avoiding your responsibilities as a citizen)
Having said that, I believe the govt needs to think again about making it easier to stay within the law in relation to tax. An example: I was recently looking into hiring a childminder. Everyone I know who has a childminder pays cash in hand. Having done some research, I can see why - it is a pretty complex process to have to register as an employer, work out PRSI and tax deductions and pay same over to Revenue if you are not a business person. By way of contrast, I employed a childminder in Spain. It took me half an hour to call into the social security office, register myself as an employer of domestically based staff, formally employ my childminder and set up a direct debit for her PRSI, which was calculated there and then by the social security office staff. Tax liability was not an issue as the market rate for childminding is below the tax threshold, so the Sp govt just assume the person is not liable for tax and leave it at that. Second example: in my research I undercovered the fact that if I pay more than 40 a month to someone for childminding, I am formally their employer and so have the same liability for PRSI, tax calcuation et al as any other employer. This means that the girl who comes on average twice a month to babysit for us for a few hours is avoiding tax and I am acting illegally by not paying PRSI, signing a contract with her et al. That's just silly