LISTENING to a debate on assisted dying a couple of weeks ago, I realised that there is an important division that runs within the two sides rather than between them. In fact, it runs through every discussion of public policy or of management today. You might call it the argument between the spreadsheet and the essay.

In the spreadsheet view, what matters is what can be measured; if we have the measurements right, the answers to our problems will appear. There is a code of law which will provide for all eventualities, and our difficulty is simply to find it and see that it is applied.

This view is importantly right, and all complex societies depend on it. Reliable bureaucracies that deliver what they promise do make societies better and stronger. Well-drilled armies reliably defeat the other sort, and so bureaucratic states have come to dominate the world.

Even in strictly pacifist terms, there are many things that we want to run like clockwork, and many ways in which objective measurement is our only guard against self-deception. The mirror lies to us, but the tape measure cannot do so. In a church context, simple clear rules about safeguarding, enforced by third parties, would have cleaned up the diocese of Chichester, and stopped the founder of the Nine O’Clock Service, in Sheffield, Chris Brain.

In the context of assisted dying, and of policy more generally, this mindset concentrates on getting the model right, and takes for granted that the world will behave as it is supposed to do, if only we can get the supposition right.

Spreadsheet thought seems entirely rational to its believers. As the political scientist Henry Farrell puts it, in a context of AI: “Those who are embroiled most closely with the rationalist project have a hard time understanding its limits because those limits shape their own world view. The one weird trick of rationalism is to recompose complex problems in terms that can readily be rationalized. When that is good, it is very, very good, but when it is bad, it is horrid.”

St Paul, in this sense the original essayist, put it more succinctly: “The letter killeth, but the spirit giveth life.” Life is too various to be contained in rules, and we can make sense of it only in fragments, which may never cohere into a satisfying whole. No possible regulation can substitute for judgement, whether that judgement be human or divine.

Again, this view has obvious and indispensable strengths. When it comes to medicine, we really need the personal element. Doctors are not interchangeable elements in a spreadsheet cell, any more than care workers are. If you rely only on properly conducted experiments, you will never know that you need to wear a parachute when jumping out of a plane, since no one has ever conducted a properly randomised double blind trial in which half the participants jump without a parachute. Sometimes — often enough in contemporary life — we reach some absurd or terrible conclusions because everyone involved followed the rules, no matter how absurd the consequences.

This is the mindset that leads to English common law rather than Napoleonic codes — and so, also, to some horrific miscarriages of justice. Even in the field of medicine, the introduction of boring rule-based disciplines like checklists for surgeons and randomised control trial for drugs have saved many lives. When decisions to end life are left entirely in the hands of doctors, you can end up with Harold Shipman. Then again, the rules brought in to prevent another Shipman from embarking on a career of unchecked murder have almost certainly caused future patients a great deal of avoidable suffering.

The other strong point of an order based on judgement, not on rules, is that there are aspects to any trade or profession which can only be learned by practice, and cannot be communicated outside them. This is true even for computers playing rule-bound games: Deep Mind learned chess better than any human, or any of its predecessors, by playing uncountable millions of games against itself rather than by working to a preconceived algorithm.

The most important distinction is that a spreadsheet cannot tell you where judgement is needed. It can only demand more rules and better measurements. An essayist can sometimes see where spreadsheets are needed — but to do so requires moral qualities, such as humility. They do not come bundled with the method.