With examples, thanks.
There are many versions of PR to choose from (check out Wikipedia), and it’s easy to get bogged down in the minutia of how each system is supposed to work, which is why it ultimately is slow to expand around the world. FPTP is easy to understand. It has a simple outcome in your electoral district. People don’t seem to accept or care that the potential for disparity in representation with FPTP is kinda gross. Apparently it’s just not enough of a problem to convince them to make the leap into the unknown.
First Past the Post is used in the UK and Canada in General Elections. The country is divided into constituencies (Ridings in Canada) of roughly equal population, each of which returns (elects) one Member of Parliament (MP). All electors have a chance to vote and most votes wins, so if candidate A gets 10,000 votes, candidate B 9,999 and candidate C 9,999 then candidate A wins. An advantage of this system is that there is a clear link between the people and the representative (everyone knows who their MP is and had the chance to vote for their preferred candidate). A disadvantage is that many people feel their vote is ‘wasted’ or they can’t vote for their preferred candidate or party because they have no chance of winning, so vote for what they perceive as the least-worst option.
In Proportional Representation, much larger populations and geographic areas are grouped together and elect multiple representatives, roughly in line with the share of the vote that the party receives. This is its main advantage; every vote cast is important as it goes towards your favourite party’s total and helps them to get members elected. The disadvantage is that you’re not voting for a specific person and that the parties will typically have a “closed list”; i.e. if the area elects seven people then they will have a list of seven candidates and, because you vote for a party not a person, the candidates simply get elected from top to bottom on the list so the party chooses the order based on who they, no necessarily the electors, want to see returned.
Town with 100 people voting for 2 people running for president (one from each party) and 10 people for congress (5 from each party).
FPTP: Party 1 wins 51 votes and party 2 wins 49 votes, the entire government is controlled by people from party 1.
PP: Party 1 wins 51 votes and party 2 wins 49 votes, president is probably party 1 but congress would be 5 members from each party.
Let’s suppose we have a city with 1 million people, and a city council of 10. We could divide them one of two ways:
In the “first-past-the-post” system, we divide the city into 10 districts of 100 000 people, and have each city council person represent one district. In an election, you run for city council in your district, and whoever gets the most votes in each district wins that seat.
As an example, if you, me, and the ModBot run in our district, and I get 40K votes and change, you get 35K votes and change, and the ModBot gets just under 25K votes; I got the most votes, so I get the seat. The same thing repeats over all ten districts; with the ten winners making up the city council.
In the “proportional representation” system, you have “parties” create “lineups” – basically a list of who they want to be on the council. Then, all 1 million people vote on which party they want to win. Each party gets 1 seat for every 100 000 votes they have; and then the leftover seats get distributed based on some system. Normally, the way they do this is to divide the number of votes each party got by 1 more than the seats they already have (parties with no seats get divided by 1), and the parties with the most divided votes get the remaining seats.
As an example, my party, your party, ModBot party, and UselessExplanations party all run. My party gets 375K votes, your party gets 325K votes, ModBot Party gets 220K votes, and UselessExplanations gets 80K. 8 council seats are easy: my party gets 3, your party gets 3, and ModBot gets 2. We now divide votes by (seats+1), leaving me with (375K votes divided by 4) 94K for the last two seats, you with (325K divided by 4) 81K for the last two, ModBot with (220K divide by 3) 73K votes for the last two, and UselessExplanations with 80K votes – the top two are my party and your party; so the final council has the first four people from my list, the first four from your list, and the first two from ModBot’s list.
Some systems might divide things differently – I know some give extra weight to parties without any representation; so in that case, your fourth seat would instead go to UselessExplanations, giving them one seat.
First past the post has the advantage of being (usually) easier to understand; and tends to support voting for individuals rather than parties. However, it has the problem of being vulnerable to “gerrymandering”, or dividing districts up in a way that favors one group over another. It also tends to result in two-party systems; because going back to the example, if ModBot’s supporters preferred you over me, they would have been better off voting for you instead of ModBot – and over time, it turns out to be pretty easy for two parties to get into a position where they both serve their own interests and only superficially support the popular interest.
Proportional representation requires officially recognizing parties, and can take more work to work out all of the rules and what to do in interesting circumstances (things like parties kicking representatives out after voting); but tends to give people more options without penalizing them for supporting those options.
First past the post means for each constituency the person with the most votes gets elected. Proportional representation means that you have every party that gets a vote represented depending on the percentage of votes they got. So if a party got 10% of the votes it gets 10% of the seats in what ever the election was for even if they didnt have any consituancy where they got the most votes.
Fptp is used in for example the US and the UK.A pure PR is used in Brazil and Isreal for example and there are a lot of countries that dont use a pure PR system but either a combination of both Systems for example Germany or variation for PR like Ireland.