This book masterfully combines history of philosophy and history of ideas. It portrays Joseph Petzoldt (1862–1929) who creatively combined elements of thought of his teacher Richard Avenarius (1843–1896) and of the physicist-physiologist and philosopher Ernst Mach (1838–1916). Petzoldt developed a philosophy of “relativistic positivism” and became an influential interpreter of Einstein's theory of relativity. In her richly contextualized account, Chiara Russo Krauss discusses strengths and weaknesses of Petzoldt's thought.

Klaus Hentschel, Professor for History of Science and Technology, University of Stuttgart, Germany

Russo Krauss offers a rich and fascinating picture of Petzholt's positivism, including his accounts of the unity of science, the determinacy of law, and Einstein's theory of relativity. She shows him to be a significant bridge from nineteenth-century German philosophy to early analytic philosophy of science.

Scott Edgar, Associate Professor of Philosophy, Saint Mary's University, Canada

Chiara Russo Krauss's book on Petzoldt should be obligatory reading for anyone interested in German intellectual history from the 1890s to the 1920s. Russo Krauss situates Petzoldt in the philosophical debates of his time, illuminating not only Petzoldt's own wide-randing oeuvre, but also the work of those authors who influenced him, or who responded to him. The book is chock-a-block with intriguing historical and systematic insights. Russo Krauss' study sets a model of how best to discuss an allegedly 'minor' figure.

Martin Kusch, Professor of Philosophy, University of Vienna, Austria