Singapore should look beyond 2030 and plan for a more distant future - perhaps even one with 10 million people, former chief planner Liu Thai Ker said at a public forum on Saturday.
"The world doesn't end in 2030, and population growth doesn't end at 6.9 million," he said, referring to the planning parameter in the Government's White Paper on Population.
Singapore could do well to look ahead, perhaps to 2100 when it might have a population of 10 million, he suggested.
Mr Liu was one of five speakers at a forum organised by the Singapore Institute of Planners (SIP) and co-hosted by the National University of Singapore's Department of Architecture, on the topic of planning for 2030.
Mr Liu, who used to head the Housing Board, argued that population growth is necessary for economic growth. And since Singapore's land area is essentially fixed, higher density is thus inevitable.
But he was optimistic that "high density and a better living environment are mutually compatible". Liveability can be preserved with adequate amenities, buffers of greenery, and alternating denser and less dense areas.
Another speaker, ophthalmologist Geh Min, urged a more cautious approach towards development. The past president of the Nature Society argued that preserving green and heritage spaces helps build national identity.
Tussles between citizens and urban planners over areas such as Bukit Brown, a cemetery set to have a road built through it, show "that there are people in Singapore who care about the country - not just their neighbourhood, but the larger Singapore".
Dr Geh also invoked the idea of "public trust" land, held by the Government as a trustee for the public, rather than as a landlord. As land demand rises, she worried that the best lands might end up with private developers.
The other speakers were sociologist Paulin Straughan, transport expert Gopinath Menon and economist Chia Siow Yue.
Dr Straughan argued for valuing every citizen, given low fertility rates: "We have to stop this fixation about whether you are an old Singaporean or new Singaporean."
Mr Menon suggested ways to tackle congestion while Dr Chia spoke on Singapore's future economic challenges.
In the discussion that followed, a member of the audience suggested one way to improve land use: carry out the Selective En bloc Redevelopment Scheme, where old flats are redeveloped, on a much larger scale.
But the panellists urged caution, citing the importance of letting the elderly age in place, and the need to preserve heritage neighbourhoods.
"I don't think we should just tear down all the old HDB areas," said discussion moderator and Singapore Institute of Planners council member Tan Shee Tiong.