When you begin a game of Monopoly, you must first find out whether the people you are playing with know the rules.

A surprising number of folk think that you put the fines from the Chance and Community Chest cards into the middle of the board, and that anyone landing on Free Parking gets to collect them. You probably lost the sheet with the rules on it 25 years ago, five minutes after you acquired your set, so don't bother checking. Just take it from me, it's nonsense. Nothing happens when you land on Free Parking, and all money – just as in real life – gets taken by the bank.

So why is this variant so popular? Because, by giving inept players a chance to rake in a bit of extra cash, it postpones the moment at which they go bankrupt and get knocked out. You don't need to be John von Neumann to realise that when it looks like you're on to a loser, the best way to improve your chances is to try to establish rules which give you a better shot at winning.

In fact, David Hume, in his theory of political obligation, argued that that's what everyone tries to do. The best outcome in any situation would be to have everyone else bound by rules which don't apply to you. But since (unless they're exceptionally dim) the other participants will object to that, the best that can be managed is rules which apply to everyone.

In politics, however, establishing the rules is an integral part of the game – indeed, the most important part – which explains why politicians are fascinated by things which normal people find unbelievably tedious.

The merits of different voting systems, the powers devolved to councils and, above all, rules on funding are all hotly contested issues because they favour different parties. The current disposition of constituency boundaries, for example, gives Labour a huge electoral advantage, while many Liberal Democrats advocate state funding of political parties because they have fewer donors than either the Tories or Labour.

It is not surprising, then, that the SNP should be so keen to draw up the rules for the referendum on whether Scotland becomes independent, and keen that those rules should give the maximum possible chance of a Yes vote. And despite the ingrained political instinct to fight every proposal tooth and nail, there are some points that their Unionist opponents ought to concede (both because they are right, and because they are not worth contesting).

That is what has happened over, first, the question of whether there is going to be a referendum; second, that the voters will be those on the Scottish electoral roll, and third, that the First Minister has the right to determine the timing. There is no argument about the first, and only a fairly unconvincing one against the second. And while the third may well have been a naked attempt to gain political advantage, there is no point in going to the stake over it, because the argument would have been lost anyway.

From the Unionists' point of view, the more important battle is over the issue of whether there should be more than one option on the ballot (something for which no one has a mandate) and ensuring that the wording of the question is not biased (as all neutral observers concluded the Nationalists' suggested wording was).

Thus far, then, the game of setting the rules is playing out more or less as one might have expected, and some of us thought last week that we had actually got to the point where the politicians would start talking about the issue itself. Ed Miliband gave us his speech pointing out that Scots would no longer be British if the British state ceased to exist – not, perhaps, an exceptionally clever thing to have worked out and articulated, but an observation which undeniably has the virtue of being true, not to mention bleeding obvious.

But brilliantly, like someone in a poker game saying, "I assume Jacks are wild?" just as the dealer turns over the flop, the Yes campaign has just forestalled further debate by seeking another clarification of the rules. This it did in a beautifully passive-aggressive way, by announcing virtuously that it would accept donations of more than £500 only from registered Scottish voters.

The Scottish parliament has not yet determined any rules, and at the moment no restrictions will apply until 16 weeks before the poll itself. As a political manoeuvre, however, this is a humdinger, since abiding by the same restriction would remove not only the prospect of expatriate (including those in England) millionaires bankrolling the No campaign, but also deprive Labour, which will lead it, of access to trade union funding.

The judgment the No campaign needs to make is whether to accept the same self-denying ordinance. Though it has been announced as if it were a matter of principle, the primary effect of this declaration (whether genuinely principled or not) is to gain political advantage. I say that not because there is anything wrong about that, but merely to stress that Unionists should not lose sight of the fact.

Second, the No campaign should consider whether it will be greatly handicapped by refusing money from outside Scotland. If not, it may as well sign up. If so, when the issue is used against them (as it will be) will it have any measurable political effect?

My own guess is that it won't because, to be consistent, the SNP will have to agree not to use any of the £1 million donated by Colin and Chris Weir, since that came from their win on the EuroMillions lottery. If it is wrong for Scottish businessmen in the City of London or expat trade unionists in Leeds to fund the No campaign, it would be equally bad for the Yes campaign to be funded by French and Spanish punters.

The other point to remember is the lesson of Monopoly. The people keenest to tinker with the rules are those who think they are going to lose.