Iamblichus: the two-fold nature of the soul and the causes of Human Agency

Iamblichus’ doctrine of the soul poses a problem of internal consistency. Based on the fragments of De anima preserved in Joannes Stobaeus’ writings, the evidence provided by Priscian of Lydia and the commentary on De anima attributed to Simplicius in the manuscript tradition, the very core of Iamblichus' doctrine would appear to coincide with the notion that once the human soul has descended into the world of becoming and joined the body, it changes in substance while preserving its identity. As important studies have emphasised, this thesis was developed and formulated by the philosopher in opposition to Plotinus' doctrine that the soul possess an immutable and unchanging nature. Usually referred to as the doctrine of the “undescended soul”, the latter view rests on a strict ontological distinction between the level of the soul and those of realities superior to it. An examination of other fragments from De anima and of evidence from Damascius and Hermias of Alexandria would nonetheless appear to challenge the above reconstruction of Iamblichus' doctrine. Based on these sources, Iamblichus would seem to be drawing a hierarchical distinction among individual souls according to their relation to change. What he would be arguing is that the superior class of souls undergoes no change in substance (see in particular Damascius, Commentary on Plato’s Parmenides IV p. 24. 1-23 W.-C.). Iamblichus would thus appear to be granting certain categories of souls the same status that Plotinus confers to all souls – something Iamblichus criticises in other passages of his writing. I will be discussing this problem in the light of two passages on the two-fold nature of the human soul: the fragment of a epistle addressed to Macedonius, On Fate, preserved in Joannes Stobaeus, Anthologion II 8. 45 p. 174. 9-27; and De mysteriis VIII 6-7. Both texts link the individual soul to two principles: one included within the order of fate, the other superior to nature and free from the order of fate. The latter principle does not make the soul – each soul – belong to the intelligible realm; nor does it infuse the soul with the intelligible. Rather, it reflects the metaphysical view of participation that Iamblichus adopts to describe the one-sided relation between inferior and superior.