There are nine of you - four from London, three from Manchester and two from Glasgow. You're spending the afternoon together and are trying to decide what to do. The three options that have come up in discussion are: go for a walk in the countryside; watch the game on TV; and go out to see the latest Coen brothers movie. The nine of you agree to arrive at a common decision and to abide by that. You'll rank the three activities in preference order, and according to the method known as AV go for the activity that first attracts more than 50% of your combined preferences.
This is what happens. The four Londoners all vote country walk first, watch the game second, and movie third. The three Mancunians all vote watch the game first, movie second, country walk third. And the two Glaswegians both vote movie first, watch the game second, and country walk third. Four people want most to take a country walk. But five people least want to do this. In the event, the second preferences of the Glaswegians are added to the first preferences of the Mancunians, and watching the game beats the country walk by five votes to four.
They may have won the battle, but it's a shame about some of their songs. It is highly probable that AV will lose on Thursday. Those of us who support it will then have to take consolation from the level of argument deployed to oppose it. The Telegraph today: 'it is hard to comprehend a system where the candidate who gets the most first-choice votes is not necessarily the candidate who ends up being elected'. Did you have trouble understanding that more of those nine people don't much want to go on a country walk than do want to? David Cameron in the same newspaper: 'Under AV, the person who comes third in people's first preferences can end up coming first in the race. It makes winners of losers and losers of winners'. In my example, the country walk only 'wins' as an option by a different method of aggregating preferences than the one actually being used. Had our nine friends used FPTP, you could just as well say that the true winner, staying in to watch the game, had come second to the actual loser, going on a country walk - the activity fewest people of the nine wished to engage in on that afternoon.