<p>This work aims to shed new light on Augustine of Hippo’s mature dualistic view of the world, the master argument he advanced in support of it, and how it was different from the competing physicalist model that was both prevalent during his time and of which he had earlier been a proponent. Specifically, it aims to understand these topics in light of Augustine’s position on the relation of <i>nonphysical</i> (or <i>incorporeal</i>) objects to space. This topic has yet to be extensively discussed and the secondary claims one finds regarding the matter differ: for some authors claim that Augustine did take nonphysical objects to be located in space and others claim that he did not. I hold that part of the reason for the lack of consensus on this topic is the reliance by each group of authors on limited and distinct sets of direct quotations from Augustine’s writings. In contrast to previous treatments, I approach Augustine’s position by way of his account of <i>spatial location</i> and his account of <i>incorporeal</i> objects. On these grounds, in addition to a more comprehensive set of direct textual data, <i>Chapter 1</i> argues for <i>Modal~SLI</i> or the thesis that <i>pace</i> the affirmative position and <i>beyond</i> the negative one, Augustine was committed to the view that incorporeal objects generally, and God and human souls in particular, not only <i>lack</i> spatial location – they <i>cannot</i> be so located.<i> Chapter 2</i> argues from <i>Modal~SLI</i> in conjunction with further forms of evidence, against <i>spatial readings</i> of Augustine’s notion of <i>presence</i> and for a ca<i>usal account</i> (or <i>CP</i>). The causal account holds that Augustine took presence <i>per se</i> to be a kind of causal relation which does not require or entail spatially located <i>relata</i>. On the basis of <i>CP</i> and <i>Modal~SLI</i> and additional forms of evidence, <i>Chapter 3</i> argues against spatial readings and for a causal analysis of Augustine’s argument from presence to the incorporeality of human souls. <i>Chapter 4</i> argues on these same bases against the spatial reading and for a causal analysis of Augustine’s argument from omnipresence to God’s incorporeality. Additionally, <i>Chapters 3</i> and <i>4</i> contain extensive discussions of the support that Augustine’s provides for the premises in each of the arguments that is their focus. <i>Chapter 5</i>, which is the capstone of this project, draws out the implications of earlier chapters to advance new and more complete models of Augustine’s mature dualistic view of the world, the rational basis upon which he endorsed the dualistic model and rejected the competing physicalist one, and the comparative relations between his mature model and the physicalist one. Among the conclusions it advances are the following: (i) in including both physical and nonphysical objects Augustine’s mature view includes objects that are and must be located in space and objects that are not and cannot be located it space; (ii) in including God and human souls as nonphysical objects it includes them as objects that are not and cannot be located in space; (iii) causal claims (i.e., claims expressing causal relations) were central drivers of Augustine’s personal transition from a physicalist to a dualistic view of the world and were central elements of his impersonal or public case against physicalism and for dualism; and (iv) the dualist and physicalist models were similar in that each included physical objects, objects with spatial location, and God and human souls; but they differed in that unlike the physicalist model, the dualist model also included nonphysical objects, objects without spatial location, and numbered God and human souls as nonphysical objects and hence objects without spatial locations. </p> <br> <p> </p>