SINGAPORE - The issue of "free rider" opposition voters in Singapore has become something of a talking point online following a charged parliamentary exchange between Prime Minister Lee Hsien Loong and Leader of the Opposition Pritam Singh.

On Wednesday (Sept 2), PM Lee and Mr Singh sparred over how the Workers' Party (WP) had during the recent general election campaigned on encouraging Singaporeans to vote for the opposition, with the assurance that the PAP would still form the government of the day.

"If you say, vote for me, somebody else will vote for the PAP, and therefore the PAP will be the government, that (is what) the economists will call a free rider," said PM Lee.

"It means that you are taking advantage of somebody else who is doing their duty of electing a government for the nation. And you are not doing your part expressing your true views and preference, as a voter, whom you want to be the next government. And if everybody takes that attitude, then you are going to end up with a government which you do not want."

PM Lee, in his speech, also asked: "Can we continue to get good people into politics, to maintain the quality of the ministers and MPs, and make things happen for Singapore if more and more citizens prefer one party to form the government, yet vote for another party's candidates to be their MPs for diversity?

"At what point does a vote for a strong opposition become a vote for a different government?"

In his response, Mr Singh countered that he did not think the residents in Aljunied, Hougang and Sengkang who voted for the WP "would appreciate being called free riders".

"They're not free riders," he said. "We're not just doing nothing having been voted in. We're not just letting the other guy, the government of the day, do something. We've got to do what we have to do."

He added that when he and his colleagues joined the opposition cause, they certainly did not have "heady dreams" of becoming the government.

"Why did I do this? I believe in an opposition in a parliamentary democracy. It's not going to happen with people just hoping someone else does it. Somebody has to put his flag in the sand and, say, 'I'm going to do it'."

The WP MPs had worked hard to prove their worth to residents, he said, and residents voted for them because they know that having elected opposition MPs is ultimately good for Singapore.

"It's when you have elected opposition MPs that the government listens harder, and that means something to people. That's my view," he added.

The exchange sparked some discussions on various platforms online. Within a day, hundreds left comments on Facebook posts by politicians and observers who shared their take on the issue. A thread on online discussion site Reddit also attracted over 270 comments in a day.

The term "free rider" is often used in economics to refer to a person or group who wants to enjoy a benefit without having to pay the fair or full cost.

Free riding is seen more commonly with public goods and services, where the benefits are non-excludable - everyone stands to benefit and no one can be stopped from doing so.

While some social media users said it was not fair to point fingers at Singaporeans for voting tactically and there was nothing wrong in doing so, others felt that it would be a risk to game the system.

Some also felt that it was not the right time for politicians to engage in an "us versus them" debate.

PM Lee, in a Facebook post on Wednesday night, reiterated his points on the mindset Singaporeans should have in elections.

He stressed that they should vote because they truly support the party, whether PAP or opposition, and not because they want "the best of both worlds".

Shortly after the exchange in Parliament, MP Jamus Lim, an economics professor and WP MP in Sengkang GRC, weighed in on Facebook, saying the actions of WP voters did not strike him as free riding.

He said that Parliament seats are excludable and "when a PAP MP is elected, the opposition is necessarily prevented from accessing it".

He added that the votes in the three WP constituencies were "potentially costly" and required residents to trust that candidates would become good town councillors and MPs.

Residents were willing to do so, he added, and they had not voted tactically for the WP hoping that the PAP would still form the government.

Some observers wondered if the term free rider was being conflated with free loader, and that the difference between the two may not be clear to most Singaporeans when listening to the debate.

Among them was former Nominated MP Calvin Cheng, who in a Facebook post on Thursday, gave an example of a free rider in social sciences.

"For example, we all want clean streets. But if one of us decides to litter, we think it won't matter because everyone else is not littering. But if everyone thinks like this, then the streets will become dirty," he posted.

Free riding leads to failure as the result is now opposite to the one that was intended, he said.

"It has nothing to do with riding, and nothing to do with being a free-loader. It is definitely not an insult," he added.

In another Facebook post the same day, Mr Cheng, seemingly in response to Mr Lim's post, said it was wrong to say that just because there are costs, there is no free-rider problem.

Noting that the key is underpaying with respect to others, he said that for the majority, the costs comes in the possibility that there are no elected opposition MPs.

But many vote for the PAP because they consider the cost of not having the PAP governing to be even higher, he said.

Opposition voters who actually want the PAP to govern pay a smaller cost compared with those who want the PAP to govern and voted for them, he added.

But he noted that it is not free riding if people who voted for opposition do, in fact, want them to govern.

"However, I think many swing voters are those who want the PAP to govern, but vote for the opposition instead.

"This is an issue. Because it can lead to the opposite result," he added.