The recent sociobiology debate has raised fundamental and previously unresolved conceptual problems. Evolutionary Instability - Logical and Material Aspects of a Unified Theory of Biosocial Evolution - offers ap- proaches for their solution. The scientific applications comprise the dynamics and evolutionary instability of hierarchically organized systems, especially systems of interacting behavioural phenotypes in animals and man. The technical apparatus is thoroughly explained in intuitive terms within the text, and illustrated by numerous familiar examples and graphical representations, supplemented by an informal (...) summary and discussion. The analyses offer new theoretical perspectives to such diverse fields as philosophy of science, evolutionary biology, general system theory and sociology. (shrink)