Disproportionate proportionalism?

If you want an argument against proportional representation as an electoral method, you need look no further than Italy, who have just elected their 62nd post-war government - that's just slightly short of one every year on average. Although superficially attractive, the problem with PR is that it can result in the tail wagging the dog, with real power in the hands of minority parties with minority support. The current election in Italy came as a result of a party representing only about 1% of the electorate deciding to withdraw from the governing coalition. It is hardly surprising that the main proponents of PR in this country are the LibDems, who would almost certainly hold the balance of power under such a system. There are plenty of arguments against "first past the post" but it does generally produce positive and strong government - even if it's not one to our personal tastes.
P.S. - Since originally drafting this, it would appear that Berlusconi has a working majority without the need to involve other parties - it will be interesting to see how Italian politics deals with such an unusual situation.