Attempts to analyze controversial issues in the investment treaty system often result in participants drawing comparisons with and analogies from other legal disciplines, most notably public international law, international commercial arbitration, public law, trade law and human rights law. But how do these comparisons shape our thinking about the investment treaty system, why do different comparisons often support different answers to concrete problems, and which participants tend to support which paradigms and why? This Article critiques the role that the five most common interpretive paradigms are playing in attempts to understand the nature of the investment treaty system. It provides a schema for analyzing what these approaches reveal and obscure about the system and why they often support conflicting outcomes on controversial issues. It also explores why different actors - including states, investors, NGOs, arbitrators and academics - are likely to argue for, or default to, different paradigms based on their divergent interests and/or backgrounds.