If a new tax were introduced to collect $1.16 billion a year, would you rather see the money used to clean up the harbour, reduce class sizes at primary schools, lower rail fares or trim fees at public hospitals? Our government is not asking this question. In fact, it has never asked the public to evaluate policy options this way. Rather, it has tended to seek consent to raise new taxes on specific grounds, as Secretary for Environment, Transport and Works Sarah Liao Sau-tung did this week. Consulting on the second stage of the harbour-area water treatment scheme, Dr Liao put the following question to the public: 'Do you agree that protecting the water quality of Victoria Harbour is essential, and that it is worth you paying higher sewage charges in line with the polluter-pays principle?' To woo the public to say yes, Dr Liao held out the prospect of turning Victoria Harbour back into a fragrant harbour - as Hong Kong is known in Chinese - in which the annual cross-harbour swimming race can be held again. It has not been held since 1978. That goal can be achieved, she said, if we spend $8.4 billion in the first stage to extend a deep tunnel network to collect more sewage, expand the chemical treatment capacity of the sewage processing plant at Stonecutters Island and provide for disinfection. The new facilities would cost about $440 million to operate every year. Further ahead, depending on population growth and the build-up of sewage, another $11.1 billion may be needed for a second-stage upgrade to the facilities. The recurrent costs of running these enhanced facilities would be $720 million a year. So, the total additional recurrent cost of keeping the harbour clean would be $1.16 billion a year. Hong Kong has been discharging untreated sewage into the harbour for years. That is disgusting and should be stopped as soon as possible. Yet, if we accept the need to pay a new tax to reduce pollution, can we not argue for the introduction of new levies to achieve other desirable social goals? In practice, the community does not have an unlimited capacity to pay ever more taxes to accomplish all those goals. So difficult choices will have to be made. Much as we want the return of pristine waters, the deplorable discharge of untreated sewage has not had a major impact on the health of the population, as the sewage is flushed away by the strong harbour currents. Given a choice between spending $1.16 billion on sewage treatment and other competing social goals, it is far from clear if the majority would opt for cleaning up the harbour. For example, primary school teachers faced with being sacked because of falling enrolment are calling for a reduction of class sizes to raise the quality of education. It is estimated that if each primary class had 25 students instead of the current 35, the cost for staff would increase by about $3.6 billion a year. Presumably, if $1.16 billion in new taxes could be directed to schools every year, then the class size could be reduced to perhaps 31 or 32. Given a chance, Secretary for Education and Manpower Arthur Li Kwok-cheung probably would want us to agree that the quality of education is essential, and worth paying higher taxes for. No doubt other ministers also have their pet questions. Perhaps battles had already been fought behind closed doors before Dr Liao won the right to put her question to the public. But the community would be in a better position to make an informed decision if they were first consulted on what their priorities were, before being presented with a one-issue question that offers no competing choices. C.K. Lau is the Post's executive editor, policy