Now that the UK’s vaccination programme is beginning to offer an escape route out of lockdown restrictions, despite some hitches, attention is focusing on so-called domestic vaccine passports. Important details remain uncertain but the idea has already been criticised as potentially “divisive and discriminatory”, as well as going against “British instinct” – presumably because Covid passports are reminiscent of compulsory ID cards, the absence of which many regard as a hallmark of British liberty. The desire for freedom is, of course, pretty universal – but there are many, and incompatible, ideas of freedom.

The British philosopher Isaiah Berlin famously distinguished two from more than 200 senses of the word he claimed had been recorded by historians of ideas: “negative liberty”, or freedom from interference; and “positive liberty”, or freedom understood as self-mastery and self-determination. The former ensures that others don’t hinder your choices, while the latter aims to create conditions that give you options and make your choices truly yours and genuinely free.

Although they may seem like two sides of a coin, Berlin was suspicious of the idea of positive liberty, especially as a social or political aim. He argued that, historically, it had tended to spawn oppressive institutions and regimes: through twisted reasoning, these regimes ended up justifying not merely the suppression of most negative liberties but even arbitrary incarceration, killings and torture as lesser evils needed to bring about true individual or collective liberation.

Berlin was right about the dangers of distorted ideas of positive liberty. But it would be a mistake to conclude, as some libertarians do, that we could or should think about political freedom without it. The value of negative liberty, of freedom from interference is, at least partly, that it allows me to choose for myself the projects, relationships and pursuits that will shape my life. But if lack of access to education, healthcare and so on means that I don’t really have any worthwhile alternatives to pursue, negative liberty alone surely isn’t worth having.

Negative liberty is freedom from the kinds of interference that – by whatever means – prevent or compel action. Having it doesn’t mean that you are free to do whatever you want, however unimpeachable. Your lack of talent may prevent you from becoming a great singer. But when others coerce you to do things or not to do things, then they curtail your negative liberty. And that is precisely what governments everywhere, and in many cases to an extraordinary degree, have done during the current pandemic.

Often using emergency legislation, they have imposed curfews and lockdowns of varying stringency that interfere with freedom of movement and of association in every aspect of life: from family and friendship to work and religious practices. They have impeded or restricted access to trade and commerce, as well as entertainment, culture and sports. They have mandated the use of face coverings.

Lockdown and related measures haven’t taken away our ability to do all the things that constitute ordinary life but have deprived us of the opportunities to do them, whether by the threat of sanctions or by active prevention. Some people have questioned whether this massive curtailment of negative liberty is justified.

More than 160 years ago John Stuart Mill argued that in a “civilised community”, the only justification for government coercion is the prevention of harm to others. In the UK, and many other countries, long before Covid, coercive state measures, from taxes to car seatbelts, were pervasive and accepted on grounds that go beyond Mill’s justification, or at least involve a very broad interpretation of his harm principle.

The extensions include harm to oneself, justified possibly on the grounds that where there is a welfare state, certain harms to yourself indirectly harm others – and the idea that harm can be caused by omission as well as by commission. And freedom from interference is often sacrificed for the sake of other values, such as equality, prosperity, fairness and security – which may in turn enhance positive liberty.

But coercive lockdown and related Covid measures can be justified on Mill’s terms – the prevention of harm to others – without much stretching. Of course, in some countries, the situation has been opportunistically exploited to concentrate unchecked power in the government, and for the long term. But in most, including the UK, measures are confined to reducing the spread of the virus, thus preventing many more deaths and acute cases, and the ensuing collapse of health services.

Some have questioned whether the restrictions have been proportionate, given the demographic of actual and potential deaths, the long-term costs to the economy, which will affect the young disproportionately, and to the physical and mental health of the whole population – to say nothing of future burdens building up for health services. Those are important considerations but it matters that the Covid threat is, by the consensus of experts, grave, credible and imminent.

No doubt there have been mistakes, inconsistencies and exaggerations in the details in different places, some due to unavoidable ignorance or uncertainty, others to ineptitude, political expedience and opportunism. The proper assessment of these will take time, and the assembly and analysis of much complex information.

It is currently far from clear how Covid domestic passports could help achieve significant protective aims. If it turns out that they can, measures to mitigate risks of unfairness or invasions of privacy will be needed. Are they, in themselves, a threat to freedom? It is hard to see why – but perhaps it depends on which of those 200 concepts one has in mind.