With a strong electoral mandate behind it, now may seem an odd time for the People's Action Party (PAP) Government to review the political system, a move announced by President Tony Tan Keng Yam on Jan 15 at the opening of Parliament.

After all, why bother to fix what isn't broken?

And doesn't doing so now run the risk of giving sceptics the impression that the PAP is seizing the chance to entrench its dominance?

But the political trends of the past decade - from the growing desire for alternative voices, to how some candidates politicised the presidential elections - make this as good a time as any to embark on reforms, say observers.

In his address to Parliament, Dr Tan spoke of the need for Singapore's political system to be broad-based and to encourage clear electoral outcomes.

At the same time, it must have appropriate checks and balances, opportunities for alternative views to be aired and considered, and ensure minorities will not be shut out.

It is likely, then, that any proposed political changes will be measured against these criteria, with the aim of enabling a stable and effective government in the interest of all.

This is likely to stay constant no matter what is under review - be it the elected presidency, Group Representation Constituency (GRC) system, Nominated Member of Parliament (NMP) or Non-Constituency Member of Parliament (NCMP) scheme - all of which Dr Tan mentioned in his speech.

PAST CHANGES: EP, NCMP, NMP, GRCS

In fact, Singapore has often tweaked its political system to keep in step with the times.

Dr Tan acknowledged as much when he said: "This system must be refreshed from time to time, as our circumstances change."

NCMPs, NMPs and GRCs were three examples of alterations made to the Westminster parliamentary model in the 1980s and 1990s, to guarantee minorities and alternative voices a place in Parliament.

And in 1991, the appointment of the President by Parliament was converted into a process of one elected directly by the people.

The move came alongside expanding the constitutional powers of the President to consent to any drawing of national reserves and appointments to key public offices.

It was argued then that the President should also have the moral authority to exercise these new custodial powers - hence the need to be elected by the people.

This would be a check against Parliament and ensure that the government of the day taps the reserves for spending only in a way that is prudent and disciplined.

Presidential candidates were also required to not be members of any political parties, as the President - meant as a force of stability in politics - had to be above party politics.

The NCMP scheme was created in 1984 to ensure there would always be a minimum number of non-government MPs in Parliament even if, say, the PAP garnered all the elected MP seats at the polls.

In fact, from December 1965 when 13 Barisan Sosialis MPs walked out, to 1981, there was not a single non-PAP member elected to Parliament.

The PAP won all the seats at the four general elections in 1968, 1972, 1976 and 1980, as well as all by-elections in 14 constituencies in the same period. This streak ended only when the Workers' Party's J.B. Jeyaretnam was voted into Parliament in the 1981 Anson by-election.

Amid this backdrop, then Prime Minister Lee Kuan Yew proposed the NCMP scheme. He pointed to how the electorate had changed, with more than 60 per cent of voters aged 40 and below.

"They were teenagers or toddlers when the struggles were enacted in the 1950s and '60s. They have no idea how destructive opposition can be," said Mr Lee in 1984.

Having NCMPs in the House would give younger voters a taste of opposition politics, he said, adding that they would also "learn the limits of what a constitutional opposition can do".

In his support of the motion, then MP Chandra Das also questioned whether an entire PAP-filled Chamber was healthy for Singapore in the long run, pointing to the need to watch for the possible disenfranchisement of those who voted repeatedly for opposition parties.

In 2010, the maximum number of NCMPs was raised from six to nine, although no more than three NCMP seats have been offered in each Parliament because the number depends on how many opposition candidates are elected.

Another change to satisfy the desire for alternative voices in Parliament was the NMP scheme in 1990: this entails an MP not elected, nor even having to go through the election process like an NCMP, but selected by a committee.

Like NCMPs, these non-partisan MPs would not be allowed to vote on constitutional amendments but could join in parliamentary debates. Then Deputy Prime Minister Goh Chok Tong said the scheme was in response to the public's desire for more alternative views, while wanting the PAP to continue as the Government.

Some felt that PAP MPs did not adequately air and press views as they were subject to the Government whip and had to vote along party lines, Mr Goh acknowledged.

The NMP scheme would encourage political participation and contribution, and accommodate constructive dissent and alternative views, he said.

As for GRCs, they were mooted in 1988 to ensure a minimum number of representatives in Parliament from minority races.

The need to secure a multiracial Parliament was first raised by Mr Lee in 1982. And Mr Goh in 1988 spoke of concern over a trend of "young voters preferring candidates who were best suited to their own needs without being sufficiently aware of the need to return a racially balanced party slate of candidates".

Making it mandatory for some candidates to campaign in multiracial teams would encourage the practice of multiracial politics by all political parties, said Mr Goh.

Along the way, other ideas were proposed. Those that did not gel with the spirit of the times were not adopted.

These included the idea of proportional representation - in which parties are allocated seats in Parliament according to their share of the vote - which was brought up in commentaries and even in Parliament.

But Mr Lee argued that this would lead political parties based on race and religion, which would polarise a socially diverse Singapore.

It would also lead to weak coalition governments, he added.

The changes to Singapore's political system did not come out of nowhere, but were responses to political trends.

What are today's changing circumstances?

WHY REFRESHMENT IS NEEDED

Two trends stand out.

First, the desire for alternative voices, especially as young voters - who tend to be less enamoured of an overwhelming one-party rule - come of age at each election.

PAP leaders acknowledged as much during the recent hustings, and promised to listen to alternative voices and consult the public more widely. The GE 2015 results suggest that younger voters acknowledged this engagement even though the trend towards greater diversity and plurality is likely to continue.

Second, the elected presidency may be less of a force for stability in politics now.

This is because the presidential election has become increasingly politicised, with some observers describing it as a proxy for party politics. In the 2011 Presidential Election, the Government's preferred candidate, Dr Tony Tan Keng Yam, won by a slim margin of 7,382 votes.

As for the desire for alternative voices to be heard, this is less clear now that the NCMP and NMP schemes have helped achieve this to some extent.

WHY NOW?

With an eye to political stability, the PAP government may be wanting to address these trends sooner rather than later.

Add to this its strong mandate of 69.9 per cent from GE 2015, and this would help explain why it is embarking on a review now.

Observers point out that not only does it have the backing of voters, but also doing so from a position of strength is preferable to taking action when one is on the back foot.

"With a strong electoral mandate, having the review takes away a large part of the sting that the process and outcome are wholly self-serving," says political observer Eugene Tan, a law don at the Singapore Management University.

"Imagine if such a review was attempted after GE 2011."

Retired PAP MP Inderjit Singh says the mandate signalled that voters trust the PAP to make policy changes for the good of the nation.

"This is the best time for the PAP to consider changes to the political system that will be for the good of Singapore in the longer term," he said. "Also, we have a President who works well with the current government, so it will be easier for the Government and the President to work on the changes together."

The PAP has also tended to be pre-emptive instead of reactive.

When mooting NCMPs in 1984, Mr Lee said: "The Government need not introduce this legislation, but to do nothing may do the next Parliament and the people a disservice."

Mr Goh, in response to opposition politician Chiam See Tong, who opposed GRCs as Malays had always been elected into Parliament, also said: "We are not talking about history. We are trying to anticipate a problem in the future."

The PAP also tends to floatideas for debate long before a law is actually passed.

An elected presidency was first raised by Mr Lee in his National Day Rally of 1984. It went through several rounds of debate before being passed in 1991.

Says Associate Professor Tan: "There will still be criticism that the effort is ultimately concerned with entrenching the PAP's dominance." But he cautions against knee-jerk judgements, saying: "Let's see the process and the outcome."