At what stage should a population stop growing because it makes life worse, not better?

Do more people improve the quality of life?

It needs a certain number of people to have quality of life, with trade, culture, specialisation of work, and for many benefits of civilisation to be economically possible.

When do too many people reduce quality of life?

Across the world megaslums of over 10 million people are growing. The number of rich remains about the same but their wealth increases. The number of poor increases, and while quality of life and health has been improving to date, now these are reducing, with more crowding, more disease, more malaise.

'Too many' depends upon where. A city like Melbourne with only 3.74 million people in a State of five million, may become overcrowded with the official goal to push for another million by 2030. This growth has been promoted as a benefit - Australia's largest port, sporting and cosmopolitan cultural capital, and with many of Australia's largest companies.

Further growth has downsides.

Water is the most serious problem. Restrictions already reduce quality of life, with constant advertising campaigns to save water, and reduction of Melbourne?s famous gardens. The major proposed solutions are an ecologically damaging desalination plant, taking water from northern farmers via pipeline, at a cost to Victorian food supplies, and recycling water from sewage. Time was, Melbourne had the purest, best-tasting drinking water to be found anywhere.

Escalating prices of real estate benefit some, but harm most. Housing is beyond the reach of most young people, and mortgages can be lifelong.

Countryside and fertile local farmland is constantly whittled away.

Timber is being supplied by logging in catchments - a sure way to reduce quality of water and silt up storages with sediments and polluted runoff.

Traffic congestion reduces quality of life and proposed solutions are tunnels and ever more freeways. Pollution increases, with measurable effects. Yet the sprawling outer areas of Melbourne suffer from too little public transport.

To reduce sprawl and costs of supplying its infrastructure, pressures are to redevelop existing suburbs for denser housing, destroying liveable homes, and crowding families with insufficient outdoor play-space and recreation. The 'Australian dream' of the quarter-acre block has to be ridiculed as impractical.

With greater population size comes the crime and social problems common to big cities. More anonymity, more alienation and loneliness. More noise, now documented as a serious stress problem. Local councils of excessive size administer their business like small states. Overlarge schools in small grounds prepare children for crowded lives without community.

It becomes harder to holiday locally in uncrowded beach or country resorts.

The Victorian government relies heavily on gambling rising property values and the building industry as other industries disappear. Business also profits from mass markets.

There has been research on the ideal size of cities according to their available resources. Melbourne has gone beyond that. History also shows that size does not ensure innovative cities with the richest cultures and contributions to civilisation. Sure, London, New York, Paris. But classical Athens, Renaissance Florence and 18th century Edinburgh show how wonderful small can be.