Robert E. Butts (1928-1997) was a philosopher and historian of science whose central concerns were the distinction between the rational and the irrational. He viewed scientific rationality as our major defence against the various conditions that encourage witch hunts and similar outbursts of irrationality, with all their attendant pain and terror. Butts saw himself as a pragmatic realist, combining what he took to be the best aspects of logical empiricism with a historically informed pragmatism, deeply appreciative of the methods of science, trying to describe a kind of rationality essential in the struggle to preserve human values.
This volume gathers previously unpublished essays and lectures with some previously published, thematically related essays. It includes essays and lectures on philosophical aspects of the European witch hunt, on scientific rationality and methodology, and on the relationships between science and philosophy exhibited in the writings of such historically significant figures as Leibniz, D'Alembert, Hume, Kant, Carnap and Kuhn.

I: Witches and Witch-Hunters.- 1. Two Stories About Evil: Christianity and the Creation of Witches.- 2. The Tamblyn Lectures: DE PRAESTIGIIS DAEMONUM: Early Modern Witchcraft: Some Philosophical Reflections.- II: Philosophy and Science From Leibniz to Kant.- 3. Leibniz' Monads: A Heritage of Gnosticism and a Source of Rational Science.- 4. Rationalism in Modern Science: d'Alembert and the "esprit simpliste".- 5. Hume's Scepticism.- 6. Husserl's Critique of Hume's Notion of Distinctions of Reason.- 7. The Role of Arational Factors in Interpretive History: The Case of Kant and ESP.- 8. Kant's Theory of Musical Sound: An Early Exercise in Cognitive Science.- 9. Kant's Dialectic and the Logic of Illusion.- III: Twentieth Century Philosophy of Science.- 10. The Hypothetico-Deductive Model of Scientific Theories: A Sympathetic Disclaimer.- 11. Methodology and the Functional Identity of Science and Philosophy.- 12. Sciences and Pseudosciences: An Attempt at a New Form of Demarcation.- 13. The Reception of German Scientific Philosophy in North America: 1930-1962.