The transformation of the science of the soul between 1260 and 1360.
Aristotle’s highly influential work on the soul, entitled De anima, formed part of the core curriculum of medieval universities and was discussed intensively. It covers a range of topics in philosophical psychology, such as the relationship between mind and body and the nature of abstract thought. However, there is a key difference in scope between the socalled ‘science of the soul’, based on Aristotle, and modern philosophical psychology. This book starts from a basic premise accepted by all medieval commentators, namely that the science of the soul studies not just human beings but all living beings. As such, its methodology and approach must also apply to plants and animals. The Science of the Soul discusses how philosophers, from Thomas Aquinas to Pierre d’Ailly, dealt with the difficult task of giving a unified account of life and traces the various stages in the transformation of the science of the soul between 1260 and 1360. The emerging picture is that of a gradual disruption of the unified approach to the soul, which will ultimately lead to the emergence of psychology as a separate discipline.
This publication is GPRC-labeled (Guaranteed Peer-Reviewed Content).
Acknowledgements
Abbreviations
Chapter 1: Introduction
1.1 Subject matter
1.2 Status quaestionis
1.3 Periodisation and sources
1.3.1 A chronological list of consulted commentaries
1.4 Orthography, punctuation and translations
Chapter 2: Overview
2.1 The introduction of the De anima into the Latin West
2.2 The soul as perfectio
2.2.1 Avicenna’s influence
2.3 The soul as forma
2.3.1 Immortal but not personal: radical Aristotelianism
2.3.2 Formality and subsistence combined: Thomas Aquinas
2.3.3 A substance, but also a form
2.4 Unicity versus plurality of substantial form
Chapter 3: Methodologic al discussions
3.1 The scientific status of the scientia de anima
3.1.1 Imperceptibility
3.1.2 Simplicity
3.1.3 Potentiality
3.1.4 The study of the soul within natural philosophy
3.1.5 Radulphus Brito against John of Jandun
3.1.6 An increasing focus on the intellect
3.2 The subject matter of the scientia de anima
3.2.1 The soul as subject matter
3.2.2 The ensouled body sub ratione animae as subject matter
3.2.3 Leaving the subject matter undecided
3.2.4 Summary
3.3 The epistemic status of the scientia de anima
3.3.1 Unproblematic beginnings: Thomas Aquinas
3.3.2 Certitude and nobility combined: Anonymus Van Steenberghen and Walter Burley
3.3.3 Increasing difficulties: Anonymus Bazan, Radulphus Brito and John of Jandun
3.3.4 The final stages: John Buridan and Nicole Oresme
3.4 Conclusions
Chapter 4: The Aristotelian definition of the soul
4.1 Aristotle’s definition of the soul
4.1.1 Thomas Aquinas’s views on the matter of the soul
4.1.2 The Anonymi
4.2 Fourteenth-century interpretations
4.2.1 The substantiality of the soul
4.2.2 The actuality of the body
4.3 Can we perceive the identity of accidents?
4.3.1 Thomas Aquinas
4.3.2 Radulphus Brito
4.3.3 John of Jandun
4.3.4 John Buridan
4.4 Excursus: condemnations and polemics
4.5 Conclusions
Chapter 5: Substance, powers and acts
5.1 A curious fourteenth-century thought experiment
5.2 One soul or multiple souls?
5.2.1 John Buridan’s arguments against a plurality of souls
5.2.2 Nicole Oresme’s hesitation
5.2.3 Summary
5.3 The relation between the soul and its powers
5.3.1 Arguments against a real distinction
5.3.2 Arguments in favor of a real distinction
5.3.3 Some preliminary conclusions
5.3.4 The identification of the soul with its powers
5.4 The soul’s presence in the body
5.4.1 From annulose to perfect animals
5.4.2 Is the soul extended or not?
5.4.3 The discussion of the soul’s presence after Ockham
5.4.4 Is the power of sight really present in the foot?
5.4.5 From annulose animals to perfect animals
5.5 From animal soul to human soul
5.5.1 The intellective soul: material or immaterial?
5.6 Epilogue and conclusions
5.6.1 The fragile unity of the science of the soul
Chapter 6: Final conclusions
Bibliography
Manuscripts
Published sources
Secondary literature
Index Codicum Manuscriptorum
Index Nominum
Leaving aside these historiographical differences, one must say that Sander de Boer's study is a readable, solid and well-argued study. De Boer studies new material beyond beaten paths - concerning authors (e.g. the several Anonymi, Oresme and Jandun), as well as places (e.g. Ockham's reception not only in Oxford but also in Paris). He acutely judges the arguments of the different positions, and always offers a clear statement on them. The author surveys the existing literature and discusses it at the relevant places. In the end, one must explicitly highlight that De Boer discloses the systematic status of the relationship between soul and body in this particular period. Future scholars and students of philosophical psychology in the Middle Ages should take a look at De Boer's study in order to be able to better judge a certain position concerning philosophical psychology in a systematic way.
Thomas Jeschke, Tijdschrift voor Filosofie, 76 (2014), 2
This is a technically impressive study of an ongoing philosophical debate, to which Thomas Aquinas made a major contribution but which continued to provoke discussion. Constant J. Mews, Parergon 32.2 (2015)
Malgrado questi limiti, il libro di de Boer rappresenta un contributo importante alla storia della dottrina dell’anima, e più in generale alla storia della tradizione aristotelica. Scritto in modo chiaro, ben documentato, capace di analizzare gli sviluppi interni alla tradizione aristotelica ma anche di valutare l’impatto che su di essa ebbero esigenze teologiche e interventi delle autorità ecclesiastiche (cfr. in particolare le pp. 197-206), questo libro mostra come la scientia de anima sia nel medioevo «as much about animals and even plants as it is about human beings» (p. 4); ma al tempo stesso chiarisce come, fra XIII e XIV secolo, si sia creata una sempre più ampia divaricazione fra l’analisi delle anime non umane e quella dell’anima umana, quindi sia emersa una crescente sfiducia nella possibilità di comprendere appieno la natura di quest’ultima tramite strumenti esclusivamente razionali. Luca Bianchi, Rivista di storia della filosofia, n. 1, 2017
Frequently Asked Questions
What is "The Science of the Soul" about?
The transformation of the science of the soul between 1260 and 1360.
Aristotle's highly influential work on the soul, entitled De anima, formed part of the core curriculum of medieval universities and was discussed intensively. It covers a range of topics in philosophical psychology, such as the relationship between mind and body and the nature of abstract thought. However, there is a key difference in scope between the socalled ‘science of the soul', based on Aristotle, and modern philosophical psychology. This book starts from a basic premise accepted by all medieval commentators, namely that the science of the soul studies not just human beings but all living beings. As such, its methodology and approach must also apply to plants and animals. The Science of the Soul discusses how philosophers, from Thomas Aquinas to Pierre d'Ailly, dealt with the difficult task of giving a unified account of life and traces the various stages in the transformation of the science of the soul between 1260 and 1360. The emerging picture is that of a gradual disruption of the unified approach to the soul, which will ultimately lead to the emergence of psychology as a separate discipline.
This publication is GPRC-labeled (Guaranteed Peer-Reviewed Content).
Who wrote "The Science of the Soul"?
"The Science of the Soul" was written by Sander De Boer.
Sander de Boer is Postdoctoral Researcher at the University of Groningen (Faculty of Philosophy). He works mainly on the history of philosophical psychology.
Is "The Science of the Soul" part of a series?
Yes, "The Science of the Soul" is part of the "Ancient and Medieval Philosophy - Series 1" series. It's book 46 in the series.
Ancient and Medieval Philosophy - Series 1 presents state-of-the-art research on the history of Western thought from its origins to the beginnings of modernity.
In association with The De Wulf-Mansion Centre.

![]()
About the Series
The series' focus lies primarily on the continuity and thematic transitions between ancient, medieval and renaissance thought, but also includes volumes on specific topics related to any of those periods. ‘Philosophy' is understood broadly to include metaphysics, ethics, natural philosophy, epistemology and philosophy of mind, and philosophical theology. Since the series is particularly devoted to making available Latin and Greek source texts, we welcome critical text editions as well as contributions that are based on philological scrutiny of those texts, without losing sight of their philosophical importance.
Ancient and Medieval Philosophy - Series 1 aims to publish at least two volumes a year and accepts monographs as well as thematically coherent edited volumes in English (without excluding the possibility of French, German, or Italian contributions to edited volumes). Manuscripts should be 80.000 to 120.000 words in length.
Readership
Researchers and graduate students in ancient, medieval and renaissance philosophy, in classics and in history.
Editorial Coordinator
Russell Friedman, KU Leuven, Belgium
Editorial Board
Pieter Beullens, KU Leuven, Belgium
Lisa Devriese, KU Leuven, Belgium
Pieter d'Hoine, KU Leuven, Belgium
Jan Opsomer, KU Leuven, Belgium
Jenny Pelletier, KU Leuven, Belgium
Andrea Robiglio, KU Leuven, Belgium
Carlos Steel, KU Leuven, Belgium
Gerd Van Riel, KU Leuven, Belgium
Advisory Board
Brad Inwood, Yale Universityo, USA
Jill Kraye, The Warburg Institute, London, United Kingdom
John Marenbon, University of Cambridge, United Kingdom
Lodi Nauta, University of Groningen, The Netherlands
Timothy Noone (†) , The Catholic University of America, USA
Robert Pasnau, University of Colorado at Boulder, USA
Martin Pickavé, University of Toronto, Canada,
Pasquale Porro, Università degli Studi di Milano, Italy
Geert Roskam, KU Leuven, Belgium
Proposals
Proposals and enquiries can be sent to editorial coordinator Russell L. Friedman. Please send a preliminary abstract (3-4 pp.) and a short bio. Upon approval of this abstract, the full manuscript will be submitted to international peer review.
Please make use of the submission form to present the full manuscript to our board.
Authors interested in Open Access can consult the available funding options.
Links & Resources
What is the Table of Contents for "The Science of the Soul"?
Acknowledgements
Abbreviations
Chapter 1: Introduction
1.1 Subject matter
1.2 Status quaestionis
1.3 Periodisation and sources
1.3.1 A chronological list of consulted commentaries
1.4 Orthography, punctuation and translations
Chapter 2: Overview
2.1 The introduction of the De anima into the Latin West
2.2 The soul as perfectio
2.2.1 Avicenna's influence
2.3 The soul as forma
2.3.1 Immortal but not personal: radical Aristotelianism
2.3.2 Formality and subsistence combined: Thomas Aquinas
2.3.3 A substance, but also a form
2.4 Unicity versus plurality of substantial form
Chapter 3: Methodologic al discussions
3.1 The scientific status of the scientia de anima
3.1.1 Imperceptibility
3.1.2 Simplicity
3.1.3 Potentiality
3.1.4 The study of the soul within natural philosophy
3.1.5 Radulphus Brito against John of Jandun
3.1.6 An increasing focus on the intellect
3.2 The subject matter of the scientia de anima
3.2.1 The soul as subject matter
3.2.2 The ensouled body sub ratione animae as subject matter
3.2.3 Leaving the subject matter undecided
3.2.4 Summary
3.3 The epistemic status of the scientia de anima
3.3.1 Unproblematic beginnings: Thomas Aquinas
3.3.2 Certitude and nobility combined: Anonymus Van Steenberghen and Walter Burley
3.3.3 Increasing difficulties: Anonymus Bazan, Radulphus Brito and John of Jandun
3.3.4 The final stages: John Buridan and Nicole Oresme
3.4 Conclusions
Chapter 4: The Aristotelian definition of the soul
4.1 Aristotle's definition of the soul
4.1.1 Thomas Aquinas's views on the matter of the soul
4.1.2 The Anonymi
4.2 Fourteenth-century interpretations
4.2.1 The substantiality of the soul
4.2.2 The actuality of the body
4.3 Can we perceive the identity of accidents?
4.3.1 Thomas Aquinas
4.3.2 Radulphus Brito
4.3.3 John of Jandun
4.3.4 John Buridan
4.4 Excursus: condemnations and polemics
4.5 Conclusions
Chapter 5: Substance, powers and acts
5.1 A curious fourteenth-century thought experiment
5.2 One soul or multiple souls?
5.2.1 John Buridan's arguments against a plurality of souls
5.2.2 Nicole Oresme's hesitation
5.2.3 Summary
5.3 The relation between the soul and its powers
5.3.1 Arguments against a real distinction
5.3.2 Arguments in favor of a real distinction
5.3.3 Some preliminary conclusions
5.3.4 The identification of the soul with its powers
5.4 The soul's presence in the body
5.4.1 From annulose to perfect animals
5.4.2 Is the soul extended or not?
5.4.3 The discussion of the soul's presence after Ockham
5.4.4 Is the power of sight really present in the foot?
5.4.5 From annulose animals to perfect animals
5.5 From animal soul to human soul
5.5.1 The intellective soul: material or immaterial?
5.6 Epilogue and conclusions
5.6.1 The fragile unity of the science of the soul
Chapter 6: Final conclusions
Bibliography
Manuscripts
Published sources
Secondary literature
Index Codicum Manuscriptorum
Index Nominum
Related titles
Orality and Scribal Culture in the High Middle Ages
Timothy B. Noone (Author), Mark J. Clark (Author),
October 2026
Petri Thomae Quaestiones de formis
Petrus Thomae (Author), Garrett R. Smith (Editor),
September 2026
Summa (Quaestiones ordinariae) art. LXXIII – LXXV
Henry of Ghent (Author), Gordon Wilson (Editor), Juan Carlos Flores (Editor),
August 2026
The Medieval Aristotle
Nena Bobovnik (Editor), Clelia V. Crialesi (Editor), Lisa Devriese (Editor),
August 2026
Thomas Aquinas and Hervaeus Natalis on Concepts and Intentional Objects
Fabrizio Amerini (Author),
February 2026
Epicureanism and Scientific Debates. Epicurean Tradition and its Ancient Reception
Francesca Masi (Editor), Pierre-Marie Morel (Editor), Francesco Verde (Editor),
November 2024
Quaestiones de divinis praedicamentis XXVIII-XXXII
James of Viterbo (Author), Mark D. Gossiaux (Editor), Christopher D. Schabel (Editor),
June 2024
Summa (Quaestiones ordinariae) art. LXIII-LXVII
Henry of Ghent (Author), Gordon Wilson (Editor), Girard Etzkorn (Editor), Bernd Goehring (Editor), Linda N. Etzkorn (Assisted by),
February 2024
Epicureanism and Scientific Debates. Antiquity and Late Reception
Francesca Masi (Editor), Pierre-Marie Morel (Editor), Francesco Verde (Editor),
August 2023
Questiones super I-VII libros Politicorum
Peter of Auvergne (Author), Marco Toste (Editor),
December 2022
Neo-Thomism in Action
Wim Decock (Editor), Bart Raymaekers (Editor), Peter Heyrman (Editor),
December 2021
