Do these names mean anything to you: Ho Hua Chew, Tan Chong Kee, Imran Tajudeen, Chua Ai Lin, Deirdre Moss?
Probably not, unless you have been active in the areas they champion.
That's a pity because they were, and many still are, leaders of causes that have helped Singapore become a better, more progressive society, and not just a place to make a living.
Without them and others, there might have been no Sungei Buloh bird sanctuary, no active and independent voices to fight for the preservation of heritage buildings, awareness of acquired immune deficiency syndrome or Aids, prevention of cruelty to animals, and freedom of expression in theatre and the online media.
Are these issues important for Singapore?
On its own, each of them might not make a great difference, but the collective work of social activists is far greater than the sum of the individual parts.
In fact, I believe that at this stage of Singapore's development as a nation state, their work is more important than has been acknowledged and appreciated.
When citizens work together for a common good, they not only help those they directly support - the poor and vulnerable, for example - but they also strengthen the sense of belonging and community among those involved, and whose lives they touch.
Every social activist has a particular idea of the sort of society he or she believes would make for a better place, and it is this vision which is the stuff of nation-building. It doesn't matter whether everything they believe in is right or workable.
Just as in the business world, for every successful venture, there might be a dozen failures.
And just as the economy cannot function if no one dares to try despite the possibility of failing, it is the case, too, in civic society.
How else can citizens feel they are part of one community if they do not have strong ideas about their country, where it is heading and what needs to be done to make it better?
But social activists do more than just think and talk about these things - they act on their beliefs, and their actions breathe life into civic society.
Their work isn't easy, especially in Singapore, where the Government has strong views about almost everything, and dominates many aspects of public life.
I, therefore, have great admiration for their perseverance and commitment, even if I might not agree with all of what they do.
I also think too little is known of them and their work, and contributions to Singapore.
Fortunately, there is now a new book, launched earlier this month, that tries to plug this gap, called The Art Of Advocacy In Singapore, edited by Constance Singam and Margaret Thomas.
It features 37 activists writing about their experiences, and how they have tried to overcome the challenges.
What did I learn from their stories? There were some gems.
The co-founder of the Society for the Prevention of Cruelty to Animals (SPCA), Ms Marjorie Doggett, was so passionate about her cause, she once disguised herself as a laboratory technician, so she could find out how animals were used for research.
On another occasion, she posed as an animal collector to rescue six baby orang utans and two gibbons from wildlife smugglers.
A recurring theme among many of them was the importance of doing the necessary homework and research, documenting these, and, of course, engaging the relevant authorities.
It was interesting to read how both the Nature Society and the Singapore Heritage Society found the early years of trying to talk to government agencies tough going, but it has become easier over time.
As a result, the Nature Society, for example, can count among its successes not just the conservation of the Sungei Buloh Wetland Reserve but also Pulau Ubin, Chek Jawa and the Kranji Marshes.
Perhaps the authorities are now more responsive or it could be that the two groups are better at it.
But there are also others who believe social activists should focus more on building up public support, and less on gaining credibility with the government.
Dr Tan Chong Kee, who founded Singapore's first online community Sintercom, in the early Internet days, is one of those. He wrote from the experience of having to close down Sintercom when it found it impossible to comply with new online regulations introduced in 2001. The unexpected end came after initial years of success, when it appeared to have the support of people close to the powers that be.
His lesson: "To have any hope of real success, activists must make fellow Singaporeans, not the Government, their primary audience; and build mass movements, not elite intercessions.''
There is obviously no single model for social activism here. It will be shaped by a new generation of younger Singaporeans taking over from the pioneer activists.
They will bring new ideas that are in tune with the times, and will be more adept at using new technology to reach out and mobilise support.
I hope there will be greater support from Singaporeans and the authorities to encourage them.
The latter, especially, should curb the instinct to manage and control, promoting only those who fall in line with official thinking.
There was a cautionary tale from Drama Box artistic director Kok Heng Leun. The theatre group specialises in forum theatre, where the audience participate in the play. He recounted how government agencies wanted to use forum theatre to engage the public, but only to further their own agenda.
But it could not work because, as Mr Kok, who is also a Nominated Member of Parliament, put it: "Deep empathy starts with being able to confront yourself and your value system, making yourself vulnerable, being in a state of anxiety… Only when that happens can you start seeing what others feel and want."
He was writing about forum theatre but it applies equally to the larger project of making citizens participate more fully in the country's development.
When Singaporeans work at the causes they believe in, they confront stark choices: How much are they prepared to help the poor and vulnerable, migrant workers, and take care of the environment and heritage buildings?
When they discuss these issues and take action, they acquire a deeper understanding of Singapore, and the community they belong to.
It is the stuff of nation-building.
•The writer is also a senior fellow at the S. Rajaratnam School of International Studies, Nanyang Technological University.