In some societies, in some epochs, a combination of political will, technical infrastructure and social consensus has greatly lengthened the radius of predictability and ratified expectations of stability and reliability. These are the ecosystems in which thin rules can work, at least most of the time. We associate these islands of orderliness with modernization, with gleaming, state-of-the-art airports, high-speed internet connections, efficient governments and all the other preconditions for filling our calendars with events planned months or even years in advance.

The Islands Of Orderliness

Ideally, thin rules can be executed mechanically, whether by actual machines or humans expected to perform as routinely as machines. Thin rules can be qualitative as well as quantitative, long and detailed or short and lapidary: the rules for finding the square root of a given number, for crossing streets only at intersections, and for paying train fares are all thin rules.

(Thin) Rules For Machines

A thick rule requires discretion to follow; the ability to discern among cases that may, at first glance, seem alike but, in fact, differ in significant respects.Discretion is not the whole of judgment, but it is an essential part. Judgment is the ability to bring together universals and particulars, a two-fold task. First, we must decide: which universal – which law or rule or maxim or principle – applies to this particular case at hand?

Thick Rules And Discretion, Universals And Particulars

These are all cases in which the unambiguously apt universal – the law forbidding theft, the recipe for this kind of cake, the calculation of escape velocity – must be tailored to fit the particulars at hand. Casuistry pits one universal against another in the case at hand; discretion tweaks the apposite universal to the particulars of that case. Both casuistry and discretion are feats of judgment, but not the same feat.

Casuistry Pits; Discretion Tweaks

Thin rules are transparent, clear-cut, unelaborated. In contrast to the woolly thick rules, thin rules are shorn of all mention of examples, exceptions and experience. They do not anticipate the unforeseen. Nor do they allow any latitude for discretion; indeed, they are often expressly designed to minimise discretion: for example, the rules that dictate stopping at a red light, or paying for an item in a store before pocketing it, or limiting the amount of carry-on luggage for airplane passengers.

Enter The Thin Rules

Thick rules announce a directive about how or how not to behave, clearly and succinctly, but then they go on to fatten that precept with examples, exceptions and appeals to experience (call them the three exes).Thick rules are learned by EXample and from EXperience, and they are constantly being stretched by EXceptions – the three exes (and perhaps a fourth ex, for EXtenuating circumstances). These are part and parcel of the rule itself, the woolly coat that cushions the rule against unforeseen circumstances.

Thick Rules And The 3 Exes

Executive discretion – that sovereign prerogative to decide without further justification – has lost much of its legitimacy. Just as liberal political theorists of the Enlightenment contrasted the rule of law with the rule of persons, so today’s liberal polities contrast the allegedly ‘subjective’ exercise of discretion to the ‘objective’ application of hard-and-fast rules – for example, leaving the sentencing of a convicted criminal up to the judge, versus specifying mandatory sentences for crimes. Injustices can and do result in both scenarios.

The Rule Of Law Vs. The Rule Of Persons

But, in fact, discretion straddles the line between the subjective and objective: it is subjective in that it depends on personal acuity and experience; it is objective in that it can be upheld by reasons and arguments accessible to all. The more the cognitive side of discretion is denied, the less pressure to appeal to public reason and the greater the risk of unbridled caprice: a self-fulfilling prophecy.

What Is Objective Application Without Subjective Exercise?  

For example, an early 18th-century treatise on siege warfare contains what sounds like a self-evident rule: “Always attack the enemy’s stronghold at its weakest point.” But exceptions immediately follow: if a good paved road that made the transport of heavy cannons and munitions easier led to a stronger part of the fortifications, then the attack should begin there instead.

Example: The Weakest Point

The power to exercise discretion, whether in the court, the classroom or a government office, invites gimlet-eyed scrutiny for the least sign of abuse – or simple error. Distrust shadows discretion like a private eye shadowing a suspect, just waiting to catch the culprit red-handed. As a result, discretion has been driven underground, still in constant but now clandestine operation. It’s become the indispensable faculty that dare not speak its name.

Discretion = Abuse And Error

For example, in the case of a married couple who disagree whether their child should be vaccinated, we are likely to want to know more specifics about both the marriage and the risks run by the child, in order to temper the application of whichever principle we have decided should trump in this case. Either marital trust or the child’s welfare may suffer, depending on the decision, but there is a further duty to try to minimise the harm.

The Further Duty

Thin rules and thick rules have both existed since antiquity, and they can both flourish under different kinds of polities, albeit for different reasons: a democracy may favour thin rules in the name of equality, while a dictatorship may use them to curtail freedom. Wherever thin rules emerge, they presuppose a world without surprises.

(Thin) Rules For A World Without Surprises

But although our world is less variable and more predictable today, it is not yet a frozen world. And as long as universals can be ambushed by unforeseen particulars, discretion will have to come to the rescue. The only question is whether it does so furtively and secretly or openly, once again recognised and respected as a form of public reason.

Discretion As A Form Of Public Reason

Discretion is the faculty of it-all-depends. When a general rule collides with recalcitrant particulars, it is discretion that sorts out the resulting muddle. No rule can encompass all the situations to which it may have to be applied, and the shuffle of human affairs is constantly dealing us wild cards. Not for nothing does St Benedict call discretion ‘the mother of all virtues’. When universal rule and particular situation don’t align, it’s discretion that leaps into the breach. We couldn’t live without it.

Discretion: The Faculty Of It-All- Depends

What kind of harm depends on the kind of general rule. In a court of law, injustice might result from, for example, applying the full rigour of the law against theft to a poor, hungry person who stole food. In the kitchen, following the cake recipe’s instructions about the amount of baking powder may result in an oven explosion if you’re cooking at high altitude. In a spaceship launch, not taking into account how far the launchpad is from the equator when calculating the amount of fuel needed for a rocket to reach escape velocity can crash the rocket and its payload.

The Harm And The Rule

But such islands have also existed in the past, albeit on a smaller scale, and all are precarious, whenever and wherever they emerge. Modernization may be irreversible, but ruliness is not. No one who survived the pandemic years of 2020-21 needs to be reminded that life is uncertain. Everything was normal, running smoothly along the tracks laid down by modern life, until suddenly it wasn’t. Life-as-we-knew-it, a life of predictable routines, reliable expectations and planning that stretched months and years into the future – all that ended abruptly in the early months of 2020.

Modernization May Be Irreversible, But Ruliness Is Not

Judgment, especially that form of judgment known as discretion, was made to deal with situations of high variability and unpredictability. Historically, discretion was rule-governed, but by thick rules rather than thin ones. Thick rules anticipated the mismatch between universals and particulars in ways that thin rules, crafted for a world of punctual trains and just-in-time supply chains, do not.

Discretion As A Form Of Judgement

So discretion is the second form of judgment, mustered after that first decision about universals and particulars has been made: this is indeed the right universal for these particulars, but its rigid application without some adjustment to these particular particulars would cause some unintended harm.

The Particular Particulars

Discretion, therefore, combines intellectual and moral cognition. But discretion goes beyond cognition. Discernment would count for naught if one could not act upon those meaningful distinctions. The executive side of discretion implies the freedom and power to enforce the insights of the cognitive side of discretion. Discretion is a matter of the will as well as the mind.

Executive Discretion 

A hypertrophy of hair-splitting is the besetting sin of scholasticism, and a mind that makes too many distinctions risks pulverising all categories into the individuals that compose them, ultimately requiring as many rules as there are cases.In contrast, discretion preserves the classificatory scheme implied by rules, but draws meaningful distinctions within those categories. What makes these distinctions meaningful is a combination of experience, which positions discretion in the neighbourhood of prudence and other forms of practical wisdom, and certain guiding values.

Cognitive Discretion

The suspicion that dogs discretion in many modern societies is aimed at both its cognitive and executive aspects. On the cognitive side, discretion seems opaque, akin to darkling intuition and therefore irredeemably subjective. We exercise discretion all the time, but we can’t give rules for how we do it – at least, not the kind of rules now generally recognised to be such.

Discretion, The Opaque

And yet we’re uncomfortable living with it. We like our rules clearcut and unambiguous, and above all consistently applied. We equate rules applied the same way to all people in all situations with equality and predictability, two cardinal virtues of the rule of law. Exceptions immediately trigger suspicions of special pleading, unfair treatment or wanton caprice.

Rules = Equality And Predictability

The judge who arraigns a suspect must figure out what charge to book; the doctor must decide the diagnosis and treatment for the individual patient. Because this kind of judgment is all about cases, it is sometimes called casuistry. Here, judgment must decide which moral principle takes precedence. In other words, casuistry tries to figure out which rule or principle should dominate in each specific case.

Casuistry

Take another obvious-sounding rule from a 17th-century handbook on how to play various games: in chess, don’t sacrifice a piece worth more for one worth less. Yet in the next breath comes an exception: should your adversary seem to have a penchant for playing a particular piece – say, a knight – then you should do your utmost to put the knight out of commission, including sacrificing a piece of higher value (say, your bishop), in order to discombobulate your opponent and gain a psychological advantage.

Example: The Favourite Piece

How did this happen? The decline in the fortunes of discretion is part of the history of rules. That history is long and labyrinthine, and rules have always meant many things: the rules of arithmetic calculation, of games, of warfare, of cookbooks, of parliamentary procedure, of traffic, of musical composition, of spelling, and on and on. There is no known human culture without rules, and almost no human activity that slips through the tightly woven mesh of rules. But amid this dazzling diversity and ubiquity, we can make out two broad categories: thick rules and thin ones.

The Decline In The Fortunes Of Discretion

On the executive side, egalitarian democratic polities are wary of all authority that might privilege one individual or group above another and therefore restrict authority by rules – notably laws and bureaucratic procedures. Once again, discretion seems unruly by these standards, and therefore no better than a personal whim. What all reservations about discretion share is the equation of public reason and public right with rules.

Discretion, The Ruleless And Unruly

As a practical tool, discretion has two sides, one cognitive and the other executive. To be able to distinguish between cases that differ from one another in small but crucial details is the essence of the cognitive aspect of discretion, an ability that exceeds mere analytical acuity. Discretion draws additionally upon the wisdom of experience, which teaches which distinctions make a difference in practice, not just in principle.

The Two Sides Of Discretion

The choice, then, is not between thick and thin rules: we need both the resilience of thick rules and the predictability of thin ones. The challenge is to map out the territories where each works best, identifying patches of high and low variability, and designing rules accordingly. Where stability and reliability reign, rules can be as thin and unforgiving as a designer dress; where there is considerable fluctuation and variability, thick rules build in room for discretion, like elasticised sweatpants.

Couture And Sweatpants

Discretion: Hard To Live With; Even Harder To Live Without. 

When the rules break down, you must judge what to do on your own. Discretion is necessary for navigating the muddle of life