Does the mind consist only of conscious experiences, or do mental states extend beyond awareness to unconscious brain states with genuine representational content? This second volume in Jerome C. Wakefield’s trilogy immerses readers in one of the most enduring debates in intellectual history—the multi-century dispute over unconscious mental states. Beginning with Descartes’ consciousness criterion and Leibniz’s divisibility argument, Wakefield reconstructs successive rounds of argument through Locke, Mill, and others, culminating in a dialectical confrontation between Freud and William James and a novel argument for the importance of dreams in the debate.

Building on Volume 1’s analysis of Freud’s conceptual and theoretical arguments, this book examines the empirical dimension: whether phenomena such as memory, unnoticed mental states, gaps in reasoning, post-hypnotic suggestion, and dreams demonstrate unconscious mentation. Wakefield situates Freud’s position within the philosophy-of-mind tradition and shows how Freud’s synthesis helped pivot psychology from Cartesianism to a representational view of mind that underpins modern cognitive science.

Combining historical depth with analytic rigor, this volume clarifies what was at stake, what was established, and what remains unresolved—namely, the missing criterion for unconscious representation. Essential reading for scholars and advanced students in philosophy of mind, psychoanalysis, and the history of psychology, it also sets the stage for Volume 3’s engagement with post-Freudian analytic philosophy.

Jerome C. Wakefield is Professor of Social Work, Associate Faculty in Philosophy and in the Center for Bioethics, School of Global Public Health, and Honorary Faculty at the Institute for Psychoanalytic Education, New York University, USA. Author of over 300 publications across psychology, philosophy, and psychiatry, his books include The Loss of Sadness (2007) and Foucault versus Freud (2025).