Tony Abbott's call for a national plebiscite on a carbon tax is understandable as a political tactic. It is a means of focusing public attention on what polls have suggested is a lack of majority support for the reform. It also reinforces his argument that the Gillard government lacks a mandate to introduce the tax.

Whatever its political merits, the plebiscite is a bad idea. A popular vote makes sense when a government needs an extra tick of approval to proceed with policies such as on daylight saving. It does not work when forced on a government by an opposition.

If nothing else, plebiscites are non-binding, and so the government would be free to ignore the outcome. Indeed, the Prime Minister could announce before the vote that she will proceed with a carbon tax whatever the result.

Julia Gillard could base her position on the representative traditions of our system of government. She could state that her government was elected to make decisions on behalf of the people, and that she would be abdicating her responsibility by acceding to an opinion poll.

Plebiscites are rare in Australia. They go against the grain of a system in which we elect parliamentarians to make decisions on our behalf. By contrast, referendums and plebiscites introduce an element of direct democracy that allows people to have a say.