Let's look at a couple of these arguments:
"AV will mean the end to MPs jobs for life"
This argument is best illustrated by the comment from Greg Dyke, former boss of the BBC:
"In constituency after constituency, what matters is not getting the electorate to support you but getting the party to nominate you," said Dyke, who resigned from the BBC in 2004 and is now chair of the British Film Institute.
At the national launch of the Yes to AV campaign in London, he said: "Once nominated you've got a job for life in seat after seat which is why we've got rather average politicians. AV will begin to change that."
"Politicians are going to have to work harder to get our support and work harder to keep it," he said.
"You don't get jobs for life in anywhere else in Britain today so why should you in politics?"
Mr Dyke is correct in his assertion but incorrect in saying that AV will change this - after all in roughly a third of seats the MP gets over 50% of the vote and, under AV, these MPs would have those jobs for life. I very much doubt whether Barnsley Central will elect anything other than a Labour MP and Tunbridge Wells a Tory - sounds like a job for life to me!
"AV will mean the BNP and other extremists getting elected"
Here's Sayeeda Warsi scaring us with the 'fear of fascism' line:
"AV could see candidates pandering to extremist voters - because to win a seat they will need to win the support of people whose first choices have already been eliminated," she said in an article for the Sun.
"It could have serious repercussions in constituencies where the BNP vote is bigger than normal.
"It's not hard to imagine where AV could lead in places like Dewsbury - more inflammatory campaigns, and policies which appeal to extremists."
Sorry but this isn't true either - in an AV system people are more likely to vote for smaller parties (after all they are being told their vote 'counts' more) which would include extremists like the BNP and the Green Party but I can see no circumstance where a candidate actively seeks endorsement from racist or extremist candidates - for the simple fact that, even under AV, it is first preference votes that matter most and courting fascists or communists will threaten that support.
"But is isn't fair, is it?"
The biggest argument from those advocating change is the idea of "fairness". Setting to one side the fact that no choice system delivers a fair result where there are more than two choices, we need to ask whether AV really is any more equitable that the current system. I don't believe that it is any fairer - the results are just as distorting, there are (small) risks of non-monotonicity and some votes are accorded more value than others.
I have felt for some while that our system of governance needs attention. Indeed, the tinkering of Blair's government so as to fudge the issue of Scotland made things worse and the decision to, in effect, institutionalise political parties further extended the grip of Westminster's elite on the system. But the system by which we choose MPs is far less of a problem than the malign influence of party whips, the ability of very wealthy individuals and rich trade unions to buy political parties or the decline in parliament's influence as Executive elites in Whitehall and Brussels come to dominate decision-making.
Changing the voting system will not resolve any of these problems - yet the advocates of change seem to want us to believe that somehow, as if by magic, the democratic deficit in British governance will be waved away by switching to Nick Clegg's "grubby little compromise". What we would get as a result is just what we have now - only harder to change. We won't get the reformed party funding system we need, we won't have the 'in-out' referendum on Europe we want and we'll see the same old faces engaged in a depressing caucus race of privilege.
So I shall be voting No in the referendum on 5th May. Not because we don't need change - we surely do and urgently. But because switching the voting system isn't the change we need.