'First Past The Post' is the system used in Canada, the US and the UK to determine winners of general elections, It is widely agreed that the results do not reflect the true wishes of the electorate. It is, however, supported for its simplicity if for no other reason. Its only benefits are that it is easy to understand and to count.
To a greater extent than many other electoral methods, the first-past-the-post system encourages tactical voting. Voters have an incentive to vote for one of the two candidates they predict are most likely to win, even if they would prefer neither candidate to win. A vote for any other candidate is considered to be likely "wasted" and bear no impact or benefit on the final result they would prefer—and in many cases, harm it.
The position is sometimes summarized, in an extreme form, as "ALL VOTES FOR ANYONE OTHER THAN THE RUNNER UP ARE VOTES FOR THE WINNER".
It is generally, but not universally, agreed that the most accurate representation of voter wishes in a parliamentary system such as that of Canada is a parliament comprised of political party members in proportion to the percentage of votes received in the election overall. Therefore, if there are 100 seats in parliament and five parties and the vote percentages are 39%, 32%, 20%, 5%, 4% the party representation in parliament should likewise be 39, 32, 20, 5, 4. The chances of this occuring in a Canadian election under the 'First Past The Post' system are likely about the same as winning Lotto 6/49.
'First Past The Post' produces an indisputably true and accurate representation of the voters preferences in ONE and only ONE situation. In that situation there are two candidates and a single voting group. That would exclude any situations where there are multiple voting districts or other subdivisions, whether they have the same candidates or different candidates.
In a single two candidate election with 21 voters if candidate A gets 11 votes and candidate B gets 10 votes, candidate A is clearly (and obviously) the winner and the preferred candidate of the electorate.
If there are multiple districts, however, things are a bit less cut and dried. Candidate A might get the largest total number of votes but Candidate B might win the most districts. Then it must be decided whether winning the most votes or winning the most districts is the more accurate reflection of voter wishes.
In a scenario where the characteristics of the districts are extreme in their differences this might not be a simple or straighforward decision. One example that comes to mind is differences between rural and urban districts where perhaps the rural districts have fewer voters and whose needs can be and often are overlooked or ignored by the urban majority (or vice versa). In these situations, more common than not in Canada today, neither choosing the overall majority winner or choosing the greater number of districts winner would be a fair and reasonable reflection of the NEEDS of the electorate, even though either could be argued be an accurate representation of voter preferences.
It is rare in Canada to have only two candidates running for election in any district and impossible to have the same candidates running in multiple districts in the same election. Assuming that there will always be more than two candidates in all or almost all of multiple voting districts, it is crystal clear that first past the post results rarely reflect the true wishes of the electorate, assuming that the 'true wishes' are evidenced by the percent of votes cast for the political parties participating in the election.
In the 2015 Canadian election with 338 seats total the results were:
- Green 3.5% = 11.83 (12 seats) - Actual seats won = 1 (.258%)
- BQ = 4.7% = 15.88 (16 seats) - Actual seats won = 10 (2.58%)
- NDP 19.7% = 66.59 (67 seats) - Actual seats won = 44 (13.02%)
- Con 31.9% = 107.82 (108 seats) - Actual seats won = 99 (29.3%)
- Lib 39.5 = 133.51 (134 seats) - Actual seats won = 184 (55.63%)
It is also theoretically possible for the smallest districts to control the legislative assembly. If we were to imagine the scenario where there were 40 districts each with large populations and 60 districts with small populations, each electing one member it would be possible for a majority government to be made up entirely of representatives from the small constituities, maybe even with a total population less than that of only a few of the larger districts.
'First Past The Post' makes politics nastier. There is an incentive to 'vote strategically' out of fear or anger. Cooperation is also discouraged. To suggest another party has a good idea could risk bleeding your vote to another party. FPTP makes consensus difficult, and politics unstable. Voters tend to flip-flop between the two major parties. The 'spoiler' effect is also a constant threat and a frequent occurence. A single independent candidate can syphon votes away from a party making a possible winner into a loser. The prime example is the Nader candidacy in the 2000 US Presidential election. Usually the independent candidate has views and policies closely aligned with the one party and draws votes from it to the advantage of its competition.