A Big Stick and a Small Carrot: Going for Gold:

One for the free marketeers who support first past the post to ponder.

The two party system is non-competitive. It is comparable to a captive, demand constant, oligopoly market in which consumers have a choice between only two approximately equally sized suppliers.

He is, of course, completely correct. The fact that it’s bad for democracy and breaks badly when you throw more parties intot he mix is another good reason to support STV.