AVIEZER TUCKER UNIQUE EVENTS: THE UNDERDETERMINATION OF EXPLANATION ABSTRACT. The paper explicates ‘unique events’ and investigates their epistemology. Explications of ‘unique events’ as individuated, different, and emergent are philosophically uninteresting. Unique events are topics of why-questions that radically underdetermine all their potential explanations. Uniqueness that is relative to a level of scientific develop- ment is differentiated from absolute uniqueness. Science eliminates relative uniqueness by discovery of recurrence of events and properties, falsification of assumptions of why-questions, and methodological simplification e.g. by explanatory methodological re- duction. Finally, an overview of contemporary philosophical disputes that hinge on issues of uniqueness emphasizes its philosophical significance. KEY WORDS: Events, Explanation, Unique, Underdetermination. 0. UNIQUE EVENTS: THE UNDERDETERMINATION OF EXPLANATION Unique events raise five philosophical issues: 1. A philosophical explication of ‘unique events’. 2. The epistemology of unique events. 3. How can unique events be identified as such? 4. Which events are unique? 5. How can we know what can be known about unique events? Previously philosophers debated whether unique events are in some sense beyond the purview of science. Most philosophers skipped over is- sues 1–4 to answer 5, offering or rejecting alternative methods to what philosophers considered to be the scientific method, e.g. ideographic methodologies, empathic understanding, colligation, narrative understand- ing & etc. This essay concentrates on the neglected 1–4 issues, postponing a discussion of 5. First, previous attempts to explicate ‘unique events’ as individuated, different, and emergent events are rejected as philosophically uninteresting: They do not raise issues that are of concern to philoso- phers such as the nature and limits of knowledge, the constitution of the universe, the content and limits of the scientific method etc. Second, Erkenntnis 48: 59–80, 1998. © 1998 Kluwer Academic Publishers. Printed in the Netherlands.