I was at the Concurrences Digital Conference in Paris on Monday, which was a great event – in the auspicious venue of the French National Assembly – spiritual home of Liberté.

It started to focus the lens more squarely on the issue of competition policy versus regulation – and the conflicting desires to both open access to data for competition, and close down access to data for privacy. What struck me is that some elements of this debate are not new – in fact they are old. Very old.

As a wide-eyed comprehensive school kid from Leeds, I arrived under Oxford’s dreaming spires just as the new century got underway. Humanity had just survived the now forgotten “millennium bug” – something that was supposed to wreak digital havoc just as we had all finished partying – in the words of the Artist Formerly Known as Prince – like it was 1999. I guess sometimes prophecies of digital apocalypse turn out to be wrong.

Anyway, the digital era was just starting. Oxford, very unusually at that time, already had superfast internet. I vividly remember my first Google search, made from my 15th century undergraduate rooms. What it did for our education, not sure, but our digital music collections were vast (R.I.P. Napster).

The curriculum was hardly digital. My education started with a term of ethics, delivered in the old-fashioned tutorial system – debating the issues in the dusty book filled room of a venerable professor of philosophy. The subject was John Stuart Mill versus Immanuel Kant. As profitable as the undergraduate economics later turned out to be, it was this philosophical discussion that was one of the more relevant for the debates we’re now having about modernising competition policy.

Here’s what JS Mill had to say: things are right or wrong according to whether they have good or bad consequences. We should be utilitarian: seek to maximise the total sum of human happiness. He kicked off an intellectual tradition from which one can draw a straight line to modern competition policy and the principle of the consumer welfare standard. Economics has a natural allegiance to, and an intellectual inheritance from, utilitarian ethics. Economists – the outgoing chief economist at DG Comp in particular – have a utilitarian tendency to want to tear up the rulebook if they think the consumer will be better off as a result.

Kantian ethics take quite the opposite view: conduct is right or wrong not at all because of its effects, but rather because of the nature of the conduct itself. We can use rules of reason to determine whether certain behaviour is bad or not. It lends itself naturally to the idea that individuals have certain rights that can’t easily be overridden. The intellectual heritage of modern law concepts is clear. Not least the idea of a by object infringement in competition law. But also concepts of property and freedom to contract, and the right to privacy.

In fact, I think when we talk about the conflict between the economists versus the lawyers in competition policy we are actually talking about Mill versus Kant.

The debate on competition enforcement in digital markets keeps coming back to this fundamental divide. The utilitarians out there call for a dramatic change in the rules, more rapid intervention to make sure we improve outcomes for consumers. They are naturally attracted to the idea that the tech giants should be opened up to competition – grant access to their data, allow it to flow freely to rival services. But at the expense of whose rights? If these companies have done nothing wrong and have created significant intellectual property in these data, they have a right to the benefits. At the same time privacy law seeks to protect the rights of individuals – can a regulator really mandate the terms on which their data is made available to rivals for the sake of competition?

The same fundamental tension opens up when people talk casually about shifting where the burden of proof should lie in merger proceedings for digital giants. Tearing up decades (or more) of legal precedent in pursuit of an increase in the sum of human happiness (aka the supposed explosion in consumer welfare we could access if only we stopped nasty tech giants hoovering up every talented digital start-up). Moving to a balance of harms test is one recommendation of the Furman review the UK CMA was wise to reject.

Don’t get me wrong, I’m an economist. JS Mill has a lot to teach the world (especially about the tyranny of the majority – but Brexit’s another story). But we can’t pretend that the ultimate goal of consumer welfare doesn’t exist within a fundamentally rights based legal system – a system which is more than capable of making costly errors if left unchecked. This is something which Mill himself recognised as essential – even if he was a couple of hundred years too early to stop Brexit.