The Diversity of individuatio and principium individuationis
an aspect of Thomas Aquinas’s thought on individuals
2016 Volume 2016 Issue 67 Pages 153-163
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2016 Volume 2016 Issue 67 Pages 153-163
This paper examines diverse meanings of the term individuatio (individuation) in Thomas Aquinas’s writings. The paper is divided into two sections. The first section focuses on the extent to which diverse meanings of individuatio can be found. In On the Book of Causes (Super librum de causis), Lecture 9, Aquinas presents two kinds of individuatio. One is the case where something (i.e. forma) is received in subiectum and becomes individual. The other is the case where something does not need to be received in subiectum, but is already individual. Similarly, Aquinas posits individuatio through matter (materia), and individuatio by itself separately in A Disputed Question on Spiritual Creatures (Quaestio disputata de spiritualibus creaturis), Article 5. Moreover, in Summa of Theology (Summa theologiae), Part I, Question 3, Article 3, Aquinas indicates that the latter individuatio is the individuatio of form (forma) by itself. From these writings, it is obvious that there are a variety of individuationes in Aquinas’s thought.
The second section proposes the possibility of formulating diverse principles of individuation (principium individuationis) according to the diverse meanings of individuatio. The proposal is as follows: the principle of individuation can be formulated as matter in material substances, as form (strictly speaking, a separated form different from being) in angels, and as being (esse) in God. This section mainly discusses some related and important texts from On Aristotle’s Metaphysics (Super libros Aristotelis metaphysicae), Book VII, Lecture 11, and Summa against Gentiles (Summa contra gentiles), Book IV, Chapters 10 and 14. The former discussion examines a difficulty in understanding form as the principium individuationis in angels, and seeks to defend that concept. The latter discussion shows how the concept of principium individuationis is applied to God. From these discussions, we can infer that there are also a variety of principia individuationis.
