Rocco Gangle is Professor of Philosophy at Endicott College. He is the author of several books, including Diagrammatic Immanence: Category Theory and Philosophy (EUP), François Laruelle’s Philosophies of Difference: A Critical Introduction and Guide and, with Gianluca Caterina, Iconicity and Abduction (Springer), as well as dozens of journal articles and chapters in the areas of logic, phenomenology, semiotics, and philosophy of science. He is also a scholar and translator of the work of François Laruelle and co-director of the Center for Diagrammatic and Computational Philosophy.

Do I believe that category theory and diagrams can be useful to philosophy? Certainly. Does Gangle's book provide an illustration and a useful entry point for philosophers who might want to learn how to use category theory in their own research and thinking? It will depend on their sensitivity to the philosophical issues chosen by Gangle. His presentation of category theory and categorical notational systems are clear and instructive. That will certainly be useful and could be a starting point to non-mathematicians. As to whether, in the end, philosophers will be convinced and will find ways of using these concepts and notational systems in their own philosophical work, I will leave that to readers to decide.

• Acknowledgements; Introduction; 1 Spinoza and Relational Immanence; 2 Diagrams of Structure: Categories and Functors; 3 Peirce and Semiotic Immanence; 4 Diagrams of Variation: Functor Categories and Presheaves; 5 Deleuze and Expressive Immanence; 6 Diagrams of Difference: Adjunctions and Topoi; Conclusion; Bibliography.

Rocco Gangle is Professor of Philosophy at Endicott College. He is the author of several books, including Diagrammatic Immanence: Category Theory and Philosophy (EUP), François Laruelle’s Philosophies of Difference: A Critical Introduction and Guide and, with Gianluca Caterina, Iconicity and Abduction (Springer), as well as dozens of journal articles and chapters in the areas of logic, phenomenology, semiotics, and philosophy of science. He is also a scholar and translator of the work of François Laruelle and co-director of the Center for Diagrammatic and Computational Philosophy.

Do I believe that category theory and diagrams can be useful to philosophy? Certainly. Does Gangle's book provide an illustration and a useful entry point for philosophers who might want to learn how to use category theory in their own research and thinking? It will depend on their sensitivity to the philosophical issues chosen by Gangle. His presentation of category theory and categorical notational systems are clear and instructive. That will certainly be useful and could be a starting point to non-mathematicians. As to whether, in the end, philosophers will be convinced and will find ways of using these concepts and notational systems in their own philosophical work, I will leave that to readers to decide.

• Acknowledgements; Introduction; 1 Spinoza and Relational Immanence; 2 Diagrams of Structure: Categories and Functors; 3 Peirce and Semiotic Immanence; 4 Diagrams of Variation: Functor Categories and Presheaves; 5 Deleuze and Expressive Immanence; 6 Diagrams of Difference: Adjunctions and Topoi; Conclusion; Bibliography.