Do Exceptions Make a Rule Arbitrary?

Rules must usually be stated in general terms if they are to guide many people. Real situations, however, are more varied than any rule can list in advance. Applying the words without exception is therefore not always the most faithful way to apply the rule.

In Book V of the Nicomachean Ethics, Aristotle discusses equity. A law speaks generally but may misfire in an exceptional case; equity corrects the gap created by that generality. It does not simply declare the law mistaken. It asks how the lawmaker would have qualified the rule if present and aware of the particular circumstances.

Suppose a museum asks visitors to follow a route marked by ropes, to protect objects and maintain order. If a corner is too narrow for a wheelchair, a staff member may briefly open another section so the visitor can pass safely. That departure from the usual route preserves the rule’s purpose. Opening it merely to give a friend a shortcut would instead be favouritism.

My view is that an exception is not arbitrary merely because it departs from the wording. The reason must be public, relevant to the rule’s purpose, consistently available in comparable cases and open to review. A rule without exceptions can become rigid; exceptions without these constraints can dissolve the rule. Equity is not unrestricted discretion but responsibility for explaining how a general rule should meet a particular case.

https://classics.mit.edu/Aristotle/nicomachaen.5.v.html
https://plato.stanford.edu/entries/rule-of-law/