Should everybody have a right to drive? Most of you would say not. Some people are incompetent, reckless or drunk drivers who endanger others. They should be kept off the road for everyone's safety.

Jason Brennan's argument in Against Democracy is that what's true of driving is also true of voting. Some voters are so irrational and ill-informed that their preferences endanger the rest of us. Just as we have a right to be protected from bad drivers, so we should be protected from bad voters. He favours epistocracy - rule of the knowledgeable - over democracy.

I find his argument only half-convincing. He's strong at showing just how badly informed voters are. He's also good at undermining the conventional arguments for a right to vote. For example, because your vote almost certainly won't affect the outcome of an election, you lose no power by being denied a vote. Nor are your rights of self-expression limited: you can express yourselves in countless other ways.

What's more, he says, political expression often brings out the worst in us. He cites Shanto Iyengar and Sean Westwood's research (pdf) which shows extreme polarization between Democrats and Republicans, but a moment spent watching Question Time would also vindicate him.

Nor, he says, would unequal voting rights undermine equality of status. For example, I might know more about economic policy than my plumber. But this doesn't and shouldn't mean I'm a better person than him, any more than his superior knowledge of plumbing makes him my superior. Brennan says:

We should stop viewing the right to vote as a badge of equal status and instead regard it as having no more symbolic power than a hunting or plumbing licence.

Brennan is also unworried by the possibility that an unequal franchise would give more votes to (say) richer white men than to black women. For one thing, he says, if this is the case it's the product of past injustices and is an argument for rectifying those.

I'm unsure of this. Certainly, the fact that gender, class and racial injustices have persisted for decades after women, workers and blacks have had the vote suggests that universal suffrage isn't sufficient to achieve justice. But might it be necessary? Brennan thinks not. He argues that people don't vote in their self-interest, so under-represented groups would be protected by others. I'd prefer stronger safeguards.

Where Brennan is persuasive, I think, is in arguing that our right to competent government is stronger than a right to vote. As he says:

Just as it would be wrong to force me to go under the knife of an incompetent surgeon or sail with an incompetent ship captain, it seems wrong to force me to submit to the decisions of incompetent voters.

However, I have two big gripes with his theory.

One is that he seems vague about the form of epistocracy.

One possibility he suggests is that voters should set ends and informed politicians should choose means, as a man might tell a ship's captain his destination but allow him to choose how to get there. For me, this doesn't work. What if the ends are unattainable? And is there a distinction between ends and means? For example, is Brexit an end in itself or is it a means?

Another possibility is that bad candidates whom the voters choose can be vetoed by an "epistocratic council." This seems impractical. Can you imagine what would happen if Trump were to be elected president but an "elite" were to prevent him taking office?

Merely raising this question highlights a virtue of democracy which Brennan under-rates: it is a way of keeping the peace by placating the mob.

We might, however, read Brennan in a different way. Our actually-existing democracies have in fact always had epistocratic elements. In a parliamentary democracy our elected representatives should exercise superior judgment on our behalf. (And if they don't, that's because epistocracy doesn't go far enough). And independent institutions - such as central banks and the judiciary - help to prevent bad choices. One can read Brennan as a defence of these epistocratic institutions against referenda and populist sentiments. And this makes his book so very valuable now.