Pennsylvania Gov. Tom Ridge vetoed a bill last month that would have made it nearly impossible for independent and third-party candidates to get on the ballot to challenge him and most other incumbents in his state. Governor Ridge should be praised for his veto, but in explaining it he raised serious questions about current election methods in the US.

Ridge wrote that he would support less drastic hurdles to ballot access in order to have "only serious and viable candidates." Excluding "frivolous candidates," he wrote, would help "to assure that the winner of the general elections will receive a majority of the votes cast, or, at least, a strong plurality of the votes." Ridge echoes John Ullyot, a spokesman for Sen. Arlen Specter, who told The New York Times that "democracy is not well-served by the factionalism posed by nonviable third-party candidates...."

Yet, contrary to Ridge and Mr. Ullyot, most Americans see elections as an opportunity for people to come together to debate issues fully before making choices. If we restricted ballot status to candidates with a chance to win, then perhaps Bob Dole should have been struck from last year's presidential ballot. Certainly the Reform Party's Ross Perot, Green Party's Ralph Nader, Libertarian Party's Harry Browne, and other minor party candidates should have been prohibited.

Americans' response to the decision to keep Mr. Perot from debating was instructive. Despite Perot's low favorability rating, polls showed that 3 of 4 Americans wanted him to participate.

Yet Ridge has a point when he says winners should have a majority of votes in elections to executive offices such as governor and president - in contrast to legislative elections, where proportional representation systems could fairly represent both those in the majority and the minority. For third-party advocates, the sad reality is that our plurality system of elections is built for two parties. When more parties run, votes can fracture, and plurality winners abound.

Consider recent elections in other nations using plurality voting with more than two national parties: The Labour Party's "landslide" in the United Kingdom was only in seats, not votes. Like all other British winners since World War II, the Labour Party was opposed by a majority of voters - its 43 percent of the vote was less than Michael Dukakis' percentage in the 1988 presidential race.

In Canada, the Liberals retained their parliamentary majority with only 38 percent of the national vote. With four strong national parties and a regional party in Quebec, the vote was fractured such that only 1 of 12 provinces was won with a majority. Parties in different provinces won more seats than warranted by their vote totals, exacerbating regional divisions.

Could that happen here? President Clinton was opposed by most voters in his two victories. In 1992, he won just 43 percent of the national vote and a majority only in Arkansas. A majority of voters in the 49 other states opposed the candidate who won all of that state's electoral votes.

In 1912, the last election in which a third party ran strongly in congressional elections nationwide, Democrats turned 45 percent of the vote in House elections in Indiana into victories in all of the state's 13 House seats - Teddy Roosevelt's Bull Moose party split the Republican vote. In 1918, Democrats again won 45 percent of the congressional vote in Indiana - but this time a united Republican party won all 13 seats. The reversal was due largely to having a strong third party on the ballot in 1912 rather than shifts in the electorate.

Fortunately, there are ways to meet the twin goals of full participation and majority rule in elections with one winner. One solution is runoff elections. With only two candidates running in a second round, runoffs supposedly ensure that winners have majority support. But large drops in turnout are common.

Runoff elections also are costly. Second elections would cost taxpayers millions of dollars in a big state like Pennsylvania, and candidates would have to slug it out for several more weeks and duplicate expensive efforts to get voters to the polls.

Modern technology allows a far better way to seek majority winners in elections that maximize voter turnout. Australia elects its parliament and Ireland its president by a system called "the instant runoff," or "bottoms up." Voters have one vote but can rank candidates in order of preference. The ballot count operates as a series of runoffs. If no candidate wins a majority of first choices, then the last-place candidate is eliminated. Ballots of that candidate's supporters are reallocated to the next-choice candidate on each ballot. That continues until one candidate remains.

Voters can choose to rank only one candidate, but they have every incentive to rank more because ballots only move to a lower choice once a higher choice is eliminated. Not surprisingly, the democracies with the highest voter participation in the world in 1996 were Australia (with a 96 percent turnout) and Malta (97 percent), both of which use such preferential ballots.

The instant runoff is constitutional - states could adopt it immediately even for the presidential race. Some jurisdictions might need to modify voting equipment or shift to vote-by-mail elections, but in return the majority would rule, and the state would get out of the business of regulating voters' choices.

Two tests of a democracy are whether it promotes majority rule and full participation. The instant runoff meets these tests. With third parties and independents a growing, healthy force in our politics, it's high time for a change.