Saving the planet is one issue that has yet to surface in the election

One thing elections are not good for is respecting or calibrating the extent to which we, the people, hold complex and contradictory views.

One thing elections are not good for is respecting or calibrating the extent to which we, the people, hold complex and contradictory views. I contain multitudes, said Walt Whitman, and at least one of most people's multitude is a strong environmentalist. We are worried, some of the time, about the plastic, throwaway society we have created, fuelled by non-renewable oil and gas. Or about the sheer weight of human numbers on this planet squeezing out other animal and plant species, starting with the larger mammals and working down to wetland ferns. Or about the fact that we tend to measure our wellbeing as nations and as individuals in ways which take no account of the amount of damage we are doing to the environment or the sustainability of our life styles over the long term. We may worry about such things when hovering over the "organic" label in the supermarket, but we tend not to worry about them much when deciding how to cast our vote.

That is because we tend also to contain other personalities, including a multitude of car drivers, consumers of manufactured gizmos, users of central heating and air conditioning and lovers of intensively-farmed, air-freighted, packaged and refrigerated food. The question is how and where to strike the balance between our contradictory priorities. Elections are crude mechanisms for deciding that balance, and especially those held under the first-past-the-post system. One of the virtues of proportional representation is that it can make explicit, as in Germany today, the trade-offs between green and other priorities in a coalition government.

Even under the present electoral system in this country, however, it is possible to bring green pressures to bear on the three main "grey" parties. Voters with a green tendency can cast "symbolic" votes for the Green Party, which have no realistic prospect of electing a Green MP, but which help, as did the 15 per cent of the vote cast for the Greens in the 1989 Euro-elections, shift the centre of gravity of public policy debate. Alternatively, they can discriminate between the policies of the main parties, and weigh the green factor in their choice. Today The Independent provides readers with a guide to that process, to try to keep the long-termist, environmental side of the electorate's split personality to the fore.

Generally, we conclude that the Liberal Democrats are the greenest of the three large parties and the Conservatives the least green. The awkward fact for the green voter is that Labour says so little about environmental issues that, if it were returned to government, it could make either modest progress or none at all. For that reason it must be suspected that more people than last time will vote for the Green Party, which has run a buoyant and attractive campaign. When subjected to hard-headed analysis, of course, large parts of the party's programme are risibly impractical. The party's approach is backward-looking, often based on a nostalgia for a simpler, more communitarian past constructed entirely in renewable wood, a past which never existed. It is simply not possible to save the planet by abolishing the profit motive and turning the clock back on science.

The realistic route to environmental sustainability must lie in harnessing the power both of the market and of science in order to reduce energy consumption in future and preserve as much biodiversity as possible. That means using the tax system to put a price on pollution, in order to encourage us as consumers to minimise the damage we do to the environment; and it means pushing forward the frontiers of science, confident that genetics, for example, is more likely to help solve environmental problems than contribute to them.

This kind of pragmatic green programme is not on offer from any party at this election. It is most likely to be obtained through larger representation for the Liberal Democrats or ­ paradoxically ­ a big vote for the anti-free-market, anti-science Green Party. That is not an easy choice, especially when most multiple-personality voters will be weighing other important factors in their mind next Thursday. But green issues ought to be accorded a much higher priority than either Her Majesty's Government or Her Loyal Opposition seem so far willing to grant.