It’s not surprising that Tony Abbott’s plan for a carbon tax plebiscite has aroused little enthusiasm. As many have pointed out, our system just doesn’t work like that — and Abbott himself undercut the argument by equivocating on the question of whether a future Coalition government would be bound by a plebiscite result it disagreed with.

Even if the legislation were able to get through parliament, it’s unclear how a plebiscite could be funded, since laws cannot appropriate public money without the prior approval of the government (Constitution, section 56).

But it’s interesting to contrast the latest opposition tactic with last week’s moves on the so-called “Malaysian solution” for processing asylum seekers. There, instead of asserting the rights of the people against parliament, the opposition pursued, and won, a vote in both houses of parliament condemning the government’s policy.

Unfortunately for Abbott, he seems to lose both ways. Popular sovereignty via plebiscite won’t get a run, but parliamentary sovereignty doesn’t seem in great shape either, since the government made it clear that it would ignore the parliamentary vote and proceed with the Malaysian solution anyway.

So although George Williams, for example, is correct to point out that we have “a system in which we elect parliamentarians to make decisions on our behalf”, Julia Gillard is hardly in a position to say that too loudly, having just shown the impotence of a parliamentary majority.

The truth is that while we think of ourselves as a democracy where power originates from the people, our parliamentary system reflects that only imperfectly. It still bears the hallmarks of its origins in a time when the ministers were the servants of the monarch and parliament functioned as a check on their power, rather than as its source.

Parliament has effective means of checking the executive: it can impose conditions on funding or refuse it altogether, it can reject legislation it disapproves of, and as a last resort it can expel or even impeach ministers. But its powers are basically negative; they are not designed for it to take the initiative in policy making.

If you were starting from scratch to design a system of responsible government, you might well provide that a resolution of both houses of parliament would be binding on the executive. But that’s never been the case in the Westminster system; to be effective, parliament’s will has to be expressed in legislation (which in this case the Greens and the Coalition are unlikely to be able to agree on).

There is one important exception: a direct resolution of the lower house is enough to remove a government (or an individual minister) from office. Even that is a relatively modern development; it can be dated to 1742, when the house of commons forced Robert Walpole to resign, and it remained contested territory for another hundred years.

But these days that is the real basis of parliament’s power. Its supremacy is complete, provided it is willing to push an issue to a change of government if need be.

If a parliamentary majority isn’t willing to take that final step — and the current house of representatives clearly isn’t — then the government doesn’t have to worry too much about its approval. It can call the parliament’s bluff and proceed with its policies regardless, at least up until the point where they require legislation.

So when Abbott last week said that “what the Greens need to do is force the government to scrap” the Malaysian solution, what he means is that the Greens or other crossbenchers need to threaten to bring down the government in order to force a change of policy. But since the Greens and the Coalition come to the issue from opposite directions, such a threat would lack credibility.

Responsible government as we know it doesn’t mean that parliament gets to decide every issue. It decides which of the alternatives should form government, and it can change its mind about that, but until it does it has to allow that government to have its way.