UC Irvine

This dissertation defends the use of nonmonotonic logic to represent rule-based legal reasoning, as exemplified by a particular, complex statute: the Internal Revenue Code. The dissertation motivates and provides a theoretical basis for formalizing the United States tax code (and perhaps other statutes). Formalization of statutory language will make statutes more precise. Formalized statutory language that tracks the actual structure of the tax law will make it easier for theoretical work to converge with the law, and may lay the groundwork to apply artificial intelligence to tax compliance and avoidance.

To this end, the dissertation investigates and refines John Horty’s work, especially Reasons as Defaults, with particular focus on examples in that book of inappropriate equilibria—scenarios that Horty’s approach endorses that Horty finds problematic or unintuitive. The dissertation looks at Horty’s work in service of applying Horty’s work, and default logic more generally, to legal reasoning, and in particular rule-based legal reasoning.