Thinking Quantum: A New Perspective on Decisionmaking in Law

Abstract

Behavioral law and economics (BLE) is built on the observation that human decisionmaking is often incompatible with rational choice theory. But if our decisions do not follow the rules of rational choice theory, is there a general set of rules they do follow? Can BLE offer a coherent alternative to rational choice?

To the extent it has addressed these questions, BLE has struggled with them. But an emerging psychological theory called “quantum decisionmaking” may offer answers. Quantum decisionmaking offers a new perspective on how people think about probabilities — one that challenges core assumptions of rational choice theory. Specifically, quantum decisionmaking assumes that probabilistic judgments are prone to systematic path dependencies. Your next judgment is apt to be influenced by your last judgment, which was likely influenced by the one before that. By incorporating such dependencies, quantum models of decisionmaking can account for classically “rational” decisions and a variety of the heuristics and biases that animate BLE.

Quantum decisionmaking has theoretical and practical implications for law. On a theoretical level, quantum decisionmaking conceptually unifies what has sometimes been characterized as BLE’s ad hoc list of heuristics and biases. More practically, quantum decisionmaking highlights the important role that sequence plays in law’s choice architecture, and generates new, testable predictions about a variety of important law-related decisions. We identify and explore eight such predictions, which concern issues ranging from juror decisionmaking to witness lineups to policing.

Keywords: law and psychology, behavioral law and economics, law and economics, legal decisionmaking, quantum decisionmaking, heuristics and biases, cognitive biases, rational choice theory, harmless error, claim joinder, jurors, juror decisionmaking, evidence, order effects, cognitive models

JEL Classification: K00, K10, K19, K40, K49