The first objective of this paper is to emphasize the impossibility of enumerating before the fact a perfectly exhaustive set of specific rules to cover any kind of behavior. That objective is initially advanced in Parts I and II by comparing rules to two concepts: the familiar mathematical number line, and the less familiar “fractal,” a geometric construct denoting a shape whose boundaries are infinitely complex. Part III summarizes historical thinking about rule specificity, and remarks among other things the length of time that has passed since philosophers first recognized the impossibility of exhaustive advance rule construction. Part IV explores and places in jurisprudential context the relationship between two spectra of rules: the spectrum running from the particular to the general, and that running from the objective to the subjective. Part V points out that many current rule-writers and their audiences act today as though they are unaware of the long-settled impossibility of perfect advance precision, and that attempts to achieve perfect enumeration – in areas like American income tax and employee benefits law – have imposed huge, under-recognized costs on regulated populations.