Recently I made a startling discovery. Somewhere in the middle on most policy issues, I’m also firmly committed to values like political equality (one person, one vote) and the freedom of speech. But how, I wondered, could I take a Goldilocks approach to taxation (the tax burden shouldn’t be too big or too small, but just right), and at the same time go all-in on referenda and the freedom of speech? Then, all at once, the truth hit me: I am a fundamentalist – a fundamentalist liberal democrat.

What does it mean to be a fundamentalist liberal democrat? I’m actually still working that one through, but here’s what I’ve got so far. Liberal democratic fundamentalists believe that liberal democratic values are (or should be) the fundamental principles that underlie our constitutional arrangements. We also believe that these principles are the best principles to run on a political system on, and maybe even the only really legitimate ones. And, if my experience is anything to go by, we’ve probably become radicalized into our fundamentalism by a sense that our society is starting to lose sight of these basic principles.

What are these basic principles? No two liberal democrats would come up with exactly the same ones, but there are a few key values that everyone would espouse. Equality under the law (what the Greeks called isonomia), the right to a fair trial, the secret ballot – all of these would make everyone’s list. But perhaps the central liberal democratic value is the freedom of speech: a key freedom in its own right (and hence a liberal value), it’s also what allows citizens to express their views on where society is headed (and is thus a core democratic value as well).

But why should these principles get to be the ground rules of our society? Aren’t they just like any other set of ideas, like Marxism, Christianity – or, for that matter, Scientology? The answer to this is, ‘No.’ The basic principles we’ve just glanced at are distinguished by a certain neutrality: the freedom of speech, for example, doesn’t take stand on what you say; it simply insists on your right to say it. That’s different to Christianity, Marxism, or any other ideology, which have more content to them. Christianity and Marxism aren’t neutral with regard to the nature of human history; like them or loathe them, that’s part of their point.

At this point, a relativist might ask, ‘But if the point is to be neutral, why isn’t liberalism neutral about is own values, like the freedom of speech?’ The answer is that this wouldn’t make any sense, and, like a lot of things that don’t make any sense, it wouldn’t work out very well in practice. It doesn’t make sense to say that you can express whatever view you want, but that if anyone tries to stop you then we won’t take any action. This is a version of what Karl Popper called ‘the paradox of freedom’ – that freedom without any sort of rules simply leads to some people dominating others. Popper also identified a paradox of democracy, in which a democracy is allowed to take a vote on whether democracy itself is a good idea, and promptly votes itself out of existence.

The fact that this has actually happened on a couple of occasions – in Athens in 411 BC, and in Germany in 1933 – should be enough for us to be wary of such paradoxes. In the end, there’s no solution but to treat the basic principles of liberalism and democracy as special and untouchable. Democracies shouldn’t be allowed to vote themselves out of existence but should have measures in place to ensure that elections take place regularly. Liberal societies shouldn’t allow people to use their freedoms to deny others theirs – including their freedom of expression.

All this means that we can be more forthright in defending liberal democratic ideas. Disastrous wars have resulted from the idea that we should spread liberal democracy by the sword, it’s true – but that doesn’t mean that liberal democracy shouldn’t be defended, only that we should think very hard before seeking to expand it using military force.

Currently, there’s a debate about what we should do about the failure of universities to uphold the freedom of speech. To some, the idea of government intervention to guarantee these principles goes too far. It raises worries about governments telling people how to think. Except, of course, that the right to free speech doesn’t tell people how to think, or even what to say. On the contrary, it makes sure they’ll be exposed to a range of different viewpoints, and that they’ll be able to put their own views forward themselves.

That’s just one example of how we might defend the basic principles of liberal democracy. But we should also work to extend them. Direct popular decision-making – the original meaning of ‘democracy’ – through referenda is still an exceptional occurrence. And there are still important restrictions on freedom where there needn’t be, from prostitution to drugs.

But though core liberal and democratic principles can point the way on some polity issues, they won’t solve all of them for us. There are a lot of public issues that have very little to do with liberalism and democracy. There are others where it’s unclear which side liberalism and democracy are really on. Is high taxation something that supports freedom (especially for the poor), or something that impinges on our freedom to get and spend without state interference?

This is why – as I’ve just realized – I’m a moderate on most policy issues, but a fervent radical on others. Basic liberal democratic principles need to be defended and extended – and that means standing up for free speech at universities and advocating for further liberal democratic reforms in society as a whole. But it also means remembering that the actual work of liberal democratic policymaking is a complicated one, and that the best solution will often be somewhere in the middle. You see, I’m not trying to be unreasonable. It’s just that, as I’ve recently discovered, I am a fundamentalist. And I want you to be one too.

James Kierstead is senior lecturer in classics at Victoria University of Wellington in New Zealand, where his research focuses on ancient Greek democracy. He tweets at @Kleisthenes2.

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