Friday, July 25, 2014


Thomas Kjeller Johansen, The Powers of Aristotle's Soul. Oxford Aristotle studies. Oxford; New York: Oxford University Press, 2012. Pp. ix, 302. ISBN 9780199658435. $85.00.

Reviewed by Peter D. Larsen, Trinity College Dublin (

Version at BMCR home site


This recent contribution to the Oxford Aristotle Series is a thoroughgoing, systematic analysis of Aristotle's De Anima, his treatise on the soul. Johansen's book is a welcome addition to the literature on this important Aristotelian text. Ronald Polansky's expansive and excellent commentary of 2007 notwithstanding, there have been few recent single-author studies that tackle the De Anima as a whole and in all of its aspects. Johansen does this in fourteen chapters that broadly follow the thematic and investigative program of Aristotle's original work. The book begins with an examination of Aristotle's definition of the soul. It then proceeds through a discussion of the three types of soul – nutritive, perceptive and rational – and the defining capacities distinctive of each. After a brief, but interesting, discussion of locomotion, it provides some concluding thoughts on how the definition of soul developed in the De Anima relates to subsequent works like the De Sensu in which Aristotle discusses the role of psychical capacities in the activities of living beings. This, however, somewhat oversimplifies the scope of Johansen's project, for there are a number of important additional topics that he considers along the way, such as how Aristotle's psychology fits into his broader philosophy of nature, and how the capacities of the soul can be understood to fit the classic Aristotelian model of causation.

The book aims to frame Aristotle's investigation into the nature of soul in terms of his status as a faculty psychologist.1 Johansen clearly articulates this framework early in the book's Introduction: "He [Aristotle] rightly stands not just as the father of psychology, but also as the progenitor of faculty psychology" (1). This seems to be a reasonable approach to Aristotle's discussion of the soul, but I wonder if Johansen does not overstate both the significance of the claim that Aristotle was the first faculty psychologist, and the influence and import of faculty psychology today.2 Within this context, Johansen sets out to show both that the capacities that Aristotle ascribes to the soul are definitionally and operationally independent of one another and that, together, they form an integrated whole which can account for and explain the disparate activities of living beings both human and non-human. A parallel aim of the study is to place Aristotle's account of the soul within the context of his wider natural philosophy. Thus Johansen, rightly I think, considers the De Anima to be continuous with other Aristotelian works – especially the Physics and Metaphysics.

The first chapters of the book (1-4) explore Aristotle's definition of the soul as the "first fulfilment3 (entelecheia) of a natural instrumental body" (11-12). Johansen begins by examining what, for Aristotle, is the relation between a natural instrumental body and its soul. He argues that it is best to understand this relationship in terms of teleology. A natural body is designed to fulfil a particular function or functions, but on its own it possesses only the potential to achieve those ends. The soul, then, is the formal and final cause of the body – it is that which properly constitutes the essence of the body, and which allows it to carry out its peculiar functions. Thus, the body, understood as the matter of a living being, is properly speaking nothing independent of the matter-form compound that comprises the living being.

Johansen then considers the methodology that Aristotle employs in searching for the definition of soul. As he does with many topics, Aristotle begins with a nominal definition of the soul, one that is common to the views of his predecessors (the endoxa), as that which causes life. Johansen argues that Aristotle then moves from this conception, using the method of demonstrative syllogism recommended in the Posterior Analytics, to a more robust definition that has the resources to explain the nominal starting point. Thus, on Johansen's view, Aristotle's investigation treats the essential elements of the soul as middle terms in demonstrations that aim to elucidate the behaviours characteristic of living beings.

Once he has examined Aristotle's general account of the soul and the procedure by which he arrives at it, Johansen begins to look at the capacities of the soul and, in particular, how they fit into this general definition. In Chapter 3 he considers how a soul that is comprised of distinct capacities can be unitary. Johansen argues that the capacities of soul are like the letters of the alphabet; just as the letters are distinct from one another but can combine to form different words, so too can the distinct psychical capacities combine to constitute different kinds of souls. These soul-types are each defined by reference to the capacities that comprise them. But what is a capacity of the soul? Johansen places Aristotle's treatment of capacities within his theory of nature by linking it up with the Physics.4 Psychical capacities, Johansen argues, are, for Aristotle, inner principles for change that explain the activities characteristic of living things. However, this understanding gives rise to an apparent tension. For Aristotle argues in Metaphysics Theta that change requires a distinction between agent and patient; but if the capacities of soul are internal principles of change and rest then it appears that, in the case of living beings, the agent and patient of change are the same – namely, the living thing. Johansen argues that we can resolve this apparent tension if we remember that, for Aristotle, a living thing is a form-matter compound, and that the agent in the sort of change that is characteristic of the activities of living beings is the soul (the formal element) while the patient is the body (the material element).

In the central chapters of the book (5-12), Johansen looks at the individual psychical capacities – the differentia of the specific soul-types. In what might be considered a bridge chapter, Johansen examines Aristotle's claim in De Anima II.4 that in order to understand the capacities of the soul we must first understand the objects specific to each. Critics have typically interpreted the objects of the psychical capacities as efficient causes of the activities with which they are associated, following the model of perception, but Johansen argues that we ought rather to think of these objects as formal causes. For the analysis of these objects as efficient causes does not fit well with the activities of the nutritive capacity.

In the chapters that Johansen dedicates to the individual capacities of the soul (6, 9, 10, 11 and 12) he addresses some of the controversies that have arisen in the vast critical literature about these capacities. Unfortunately I do not have the space to discuss these in great detail, but I will highlight them here. In his discussion of nutrition, Johansen argues that, for Aristotle, the nutritive capacity is primary in the explanation of soul not because it is primary definitionally nor because all of the other capacities can be reduced to it, or are subsidiary to it, but rather because nutrition, and reproduction in particular, is a paradigmatic example of a living being fulfilling its end. Johansen further argues that each of the capacities of the soul is an efficient, formal and final cause of the body – the soul's material.

Next Johansen considers perception. He begins by giving an analysis of Aristotle's general account of perception, focusing largely on the different categories of perceptual objects – special, common and incidental – and the function of the medium in perception. He then turns to Aristotle's controversial claim that we perceive that we perceive. In De Anima III.2 Aristotle tells us that it is by the individual senses – sight, hearing etc. – themselves that we perceive that we see, hear and so on; but in De Somno 2 Aristotle appears explicitly to deny this. Johansen attempts to resolve this tension by arguing that it is with the common sense that the soul is able to carry out this second-order perception. This reading, he argues, squares with the De Somno passage because it is not the individual senses themselves that do the second-order perceiving, it is the common sense. It is also consistent with the De Anima because, as he argues, the common sense is not a distinct capacity, but is comprised of all the individual senses. Thus, if one's common sense perceives that one sees, then sight, to the extent that it is partially constitutive of the common sense, is involved in that awareness.

In his chapter on Phantasia (imagination), Johansen argues that it is not a distinct capacity, but is entirely dependent upon perception, which stands as its formal, final and efficient cause. Johansen then turns his attention to Aristotle's discussion of intellect. The question here is whether intellect can fit the model of soul as an inner principle of change, especially given that Aristotle himself casts doubt on this early in the De Anima. Johansen argues that it can. For despite there being no specific bodily organ associated with the intellect, there may be necessary bodily affections that accompany thinking. Intellect, Johansen argues, is dependent upon phantasia and because phantasia is dependent upon perception the intellect is, in some sense, dependent upon the bodily affections that go along with perceiving. However, the agent intellect, because it is immaterial and completely separate from body, appears to fall outside the study of nature and is rather part of first philosophy. Johansen claims that we need not think of Aristotle's discussion of agent intellect as contrary to his position that the De Anima is a work of natural philosophy; for nature, as he says, is not causally autonomous: it depends crucially on the unmoved mover – a cause of nature that is not in nature (245) and thus will enter into an explanation of nature and natural phenomena.

One of the distinctive strengths of this study is that Johansen makes frequent reference to the views of Plato in explicating Aristotle's positions. It is undeniable, not least because Aristotle tells us so in Book I, that in the De Anima he is in conversation with his predecessors and, in particular, with Plato, adopting those elements of their views that seem to him to be compelling and rejecting those he finds objectionable. Johansen, throughout the book, considers how Plato's views on a number of issues inform the direction that Aristotle's discussion takes. So, for example, when Aristotle claims that in order to understand the capacities of the soul we must first consider the objects of those capacities, he is echoing Plato's thoughts on the individuation of powers articulated at Republic 5, 477a-478a. Furthermore, when, in his discussion of the perceptual capacity, Aristotle divides the objects of sense into three categories – special, common and incidental – he is responding to Plato's argument at Theaetetus 184b-187a that perception cannot apprehend common objects. Making the reader aware of these passages in Plato adds a crucial dialectical dimension to Aristotle's project in the De Anima that is easily overlooked.

In closing, I note that this book has, on average, one typographical error in each chapter -which in my estimation is poor for a publisher of this quality.


1.   Faculty psychology aims to explain the various activities of the soul or mind in terms of a few basic capacities.
2.   Apart from Jerry Fodor's 1983 book The Modularity of Mind, Johansen marshals little evidence in support of the claim that faculty psychology is a dominant and/or influential view in psychology or philosophy. Because this appears to be such a central claim of the book, it would perhaps be worth mentioning the significance of modularity in contemporary evolutionary psychology.
3.   Johansen argues persuasively that we should translate entelecheia as "fulfilment" rather than "actuality" because the latter rendering runs the risk of being confused with energeia and the former captures the teleological sense of entelecheia (16).
4.   In Physics II.1 Aristotle gives an account of nature as an "inner principle of change and rest" (85).

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