Fuzzy Logic and the Sliding Scale Theorem

Abstract

Law operates principally in the context of ordinary transactions and relationships. Consequently it is important to develop insights into how it operates in the everyday world. To resolve recurring legal issues in everyday affairs, judges and other decision-makers sometimes use formulas. When a legal formula contains two elements, as several do, a process of fuzzy logic produces a result that is a function of a sliding scale between the elements. Thus, if physical presence in a new state + intent to remain = change of domicile, there will be degrees of each element, such that the degree of physical presence (which could be treated as a fraction between zero and one or as a point on a diagram where each of two axes runs from zero to one) combines with the degree of intent to remain, to produce a result - either acquisition of a new domicile or retention of the old one. The process and the result can best be illustrated by a diagram that, in most instances, resembles an economist's demand curve. The placement and slope of the curve will depend on the particular formula, and the curve may shift depending on what is at stake. The process is at work in several fields of law, including (at least) contracts, civil procedure and conflict of laws.