Bertrand Russell addresses the traditional gulf between mind and matter by proposing a revolutionary reconciliation. Influenced by modern physics and the new realists, he argues that the fundamental stuff of the world is neither mental nor material, but a neutral medium from which both are constructed. This perspective dissolves traditional dualisms and reframes the core problems of psychology.
The inquiry begins with a radical critique of consciousness, rejecting the doctrine that intentional direction towards an object is the essence of every mental phenomenon. Russell examines standard views from conventional psychology and demonstrates how concepts like introspection and the unified subject are theoretically problematic. Instead, he treats mental phenomena through the lens of behavior and causal relations.
A central component of the argument is the detailed examination of instinct and habit. Russell traces the continuity of behavior from protozoa to man, showing that learning and habit-formation depend upon instinctive drives without requiring foresight or preternatural wisdom. Behavior-cycles are initiated by discomfort and terminated by pleasure, providing a purely causal foundation for desires, including unconscious ones.
In exploring memory and mnemic phenomena, Russell examines how past history influences present responses. He analyzes the nature of memory-images, the feeling of familiarity, and recognition, distinguishing true memory from habit-memory. The continuity of an organism depends upon engrams and mnemic causation, bridging the gap between psychology and physiology.
The work culminates in a rigorous distinction between psychological and physical causal laws. Russell reframes physical objects as systems of correlated particulars, treating sensations as the intersection of mind and matter. By analyzing images and showing how they differ from sensations only in their causation, he lays the groundwork for a unified scientific understanding of knowledge and the world.
Ultimately, the book challenges readers to abandon traditional assumptions about consciousness and the soul. While leaving many precise technical questions open, it provides a vital framework for studying human behavior and thought through empirical observation rather than metaphysical dogmas.
