The concept of "fitness" is a notion of central importance to evolutionary theory. Yet the interpretation of this concept and its role in explanations of evolutionary phenomena have remained obscure. We provide a propensity interpretation of fitness, which we argue captures the intended reference of this term as it is used by evolutionary theorists. Using the propensity interpretation of fitness, we provide a Hempelian reconstruction of explanations of evolutionary phenomena, and we show why charges of circularity which have been levelled (...) against explanations in evolutionary theory are mistaken. Finally, we provide a definition of natural selection which follows from the propensity interpretation of fitness, and which handles all the types of selection discussed by biologists, thus improving on extant definitions. (shrink)

The present edition provides a detailed and accessible discussion ofhis theories and adds an account of the immediate responses to the book on publication.

In recent years Sir Karl Popper has been turning his attention more and more towards philosophical problems arising from biology, particularly evolutionary biology. Popper suggests that perhaps neo-Darwinian evolutionary theory is better categorized as a metaphysical research program than as a scientific theory. In this paper it is argued that Popper can draw his conclusions only because he is abysmally ignorant of the current status of biological thought and that Popper's criticisms of biology are without force and his suggestions for (...) its improvement are without need. Also it is suggested that Popper's desire to see scientific theory growth as being in some sense evolutionary may have led him astray about biology. And conversely it is suggested that since his claims about biology are not well taken his analysis of theory growth may well bear reexamination. (shrink)

Known as 'Darwin's Bulldog', the biologist Thomas Henry Huxley was a tireless supporter of the evolutionary theories of his friend Charles Darwin. Huxley also made his own significant scientific contributions, and he was influential in the development of science education despite having had only two years of formal schooling. He established his scientific reputation through experiments on aquatic life carried out during a voyage to Australia while working as an assistant surgeon in the Royal Navy; ultimately he became President of (...) the Royal Society. Throughout his life Huxley struggled with issues of faith, and he coined the term 'agnostic' to describe his beliefs. This nine-volume collection of Huxley's essays, which he edited and published in 1893–4, demonstrates the wide range of his intellectual interests. Volume 1 begins with a brief autobiography, and examines the development and progress of scientific practice and knowledge. (shrink)