Winner-take-all voting systems (among which are plurality and two-round runoff systems) hold as their central tenet that representation should be awarded to the candidates who receive the most votes. That principle may seem fair enough: everyone gets to vote, and the top vote-getters win. And certainly a candidate who wins likely will share many of the same ideas and values as the largest voting block in his or her constituency.
One clear downside to winner-take-all voting, however, is that losing candidates win nothing, even if they win substantial numbers of votes. In a two-candidate race, it is possible for 49.9% of voters to receive no representation. In a three-candidate race, that number can climb to 66.6% - much more than half the electorate can actually oppose the candidate who has earned the right to "represent" it. Examples of such "plurality" victories are common. Richard Nixon and Bill Clinton earned less than 45% of the vote in their initial presidential victories, and several American governors have been elected with less than 40% in the 1990’s. In some nations such as Russia and Papua New Guinea, the number of candidacies have multiplied such that district elections regularly are won with less than 20% of votes.
The leap of faith made by advocates of winner-take-all systems is that supporters of losing candidates will be duly represented by either the candidate who wins, even if that candidate is their ideological opposite, or by candidates elected elsewhere. They also must believe that voters’ opinions can be neatly boiled into two basic options, as typically happens in competitive winner-take-all elections in the United States.
By contrast, full representation voting systems allow like-minded groupings of voters to elect representatives to a government in direct proportion to their relative support within a multi-seat constituency. Proportional systems are designed to allocate 10% of the seats to a parties or a slate of candidates that wins 10% of the vote, 25% of the seats to those taking 25% of the vote and a majority of the seats to those winning a majority of the vote. Contrast that last example with the winner-take-all system, in which a majority of the vote can win 100% of the representation, and one begins to understand the fundamental difference between the two types of system.
Advocates of full voting systems propose that the legislature should be more like a mirror of the population, with majority and minority viewpoints represented. Note that full representation advocates still very much believe in majority rule: because full systems accurately translate the popular vote into representation, candidates or parties with the greatest support should obtain the largest share of seats in a legislature.
In fact, studies have shown that governments elected by full representation are more likely to produce policies that are in line with the "will of the majority." There are three major reasons for this tendency. First, when more voters have representation at the policy-making table, a majority in the legislature is more likely to be grounded in a majority of the electorate than when many voters are cut out of representation. Second, when political groupings can form and run candidates from across the spectrum, voters can more precisely define their representation. Third, that increased representation of viewpoints across the spectrum can lead to fuller discussion of important issues, thereby allowing majority interests to be better articulated and defined.