Unlike more widely read, fully formed, straightforward books by Aristotle, such as Politics and Ethics, De Anima asserts cryptic ideas and advances viewpoints that seem quite strange today. The editor's Introduction addresses such potential impediments for the Aristotelean neophyte and amplifies problematic issues of interest to philosophers of any acquaintance. Aristotle's subject is a general "principle of life" intrinsic to all plants and animals, not any contemporary notion about the soul (psyche) suggested by its English title, On The Soul. Aristotle's soul includes his psychology and topics such as sensation and thought. Lawson-Tancred argues that Aristotle is indifferent to the issue preoccupying epistomologists and psychologists during recent centuries, Descartes's division of subjectivity into the body and mind. He claims that Aristotle is concerned with general features of life, not with purely human issues like consciousness. In discounting consciousness, Aristotle concurs with anti-Cartesian positivists, but Lawson-Tancred argues that when Aristotle says the soul is substance, he really means it, contradicting physicalist contentions that it is an epiphenomenon or a list of special attributes. Aristotle's soul is substance, but Aristotle rejects reducing the soul's properties to the body's material.
Teleology is explanation implicating final causes, e.g., things fulfill purposes for which they were created. Scientists reject creation and ultimate purpose, and censure Aristotle for his teleological explanations. Regarding the soul, however, Aristotle suggests that to understand biological phenomena, the arrangement of material and its relationship to functions it performs is key. Recent rethinking about Aristotle's functionalism has reinvigorated his status in modern biology. Theologians generally view Aristotle's work favorably, especially his emphasis on built-in purpose and final causes. Lawson-Tancred recounts Aristotle's powerful influence on intellectual history from his immediate successors, to assimilation in the neo-Platonic West, through incorporation by Islamic and Christian theologians, connections that made De Anima so important for over 2000 years.
Lawson-Tancred also discusses Aristotle's personal history and intellectual development; his mentor, Plato, and their mutual influence; ideas of other philosophers that Aristotle encountered, and De Anima in context of his other works. He concludes by criticizing the interpretations of
Aristotle by the philosophers Brentano and Wilkes. Lawson-Tancred helps the reader to understand many ideas, but two essential concepts Aristotle developed elsewhere are prerequisite to understanding De Anima: entelechy (entelecheia) and substance (ousia). Substance or essence is the fundamental reality of existence. Form, Matter, and their composite are types of substances. Matter is the inanimate, elemental substrate of which things are composed, e.g., earth made into a statue. Form is the structure and function outlined by a formula (logos), e.g., a statue artfully shaped to resemble a woman. Things exist either in actuality (putting to use) or potentiality (unexploited capacity). Form is actuality; Matter is potentiality. Aristotle's theory is that Form combines with Matter following the the Form's plan to actualize potential. Entelechy is the possession of this intrinsic goal that is realized when Form and Matter combine. Thus, Aristotle's teleological approach is called "Entelechism." Aristotle uses entelechy repeatedly to describe the soul, as the following summary of De Anima shows.
In Book I, Aristotle describes his subject: the soul, "the first principle of living things," and considers its relation to intellect, emotion, etc. He comments on other philosophers's works: whether the soul is material, and what kind; its characteristic features (it moves, senses, and lacks body); how it produces bodily movement; etc. He criticizes theories that the soul is quantity or harmony or participates in the whole universe. He concludes that the soul lacks motion and is not material nor made of elements. Instead, the soul comprises several faculties: e.g., cognition, appetite.
Book II begins with an important formulation: the soul is the "form of the living body which potentially has life" (the organism's first actuality). Having a soul distinguishes living from inanimate objects. The soul's nutritive faculty is essential for all organisms, but animals have the faculty of sensation, separating them from plants. Thus begins a hierarchy of faculties from nutrition to intellect. In sensation, the sense organ and sense-object, like the soul and body, participate in the Form/Matter relationship. The sense organ receives the object's Form, not its matter, in Aristotle's words, "as the wax takes the sign from the ring without the iron and gold." He discusses each of the five senses, and makes a famous distinction among perceptual elements (special, common, incidental).
Aristotle concludes discussing sensation in Book III by proposing functions of the perceptive faculty that integrate individual senses. Imagination, a faculty producing imagery, mediates between sensation and intellect. Aristotle's remarks about intellect are among his most renowned, fecund, and difficult. He describes the intellectual faculty, which includes thinking
and supposition, with the same physiological approach of his sensory theory. The organ of thought receives the Form of the thought-object to realize thinking. He calls the intellect a repository of Forms and distinguishes the active from the passive intellect, providing inspiration for Thomas Aquinas's psychology. Aristotle concludes with a discussion of motivation, i.e., what puts the organism into action.
No other work contains a psychological theory like that presented in De Anima, excepting Aquinas's derivative. Its resemblance to attribute (behaviorist) theories of the mind cannot obscure Aristotle's radically different foundation. His Form-Matter and Actuality-Potentiality concepts are not explanatory, only a framework for inquiry. Its relevance, as Lawson-Tancred notes, to modern psychology depends upon identifying an empirical approach to Aristotle's Form. Aristotle's proposal that life has, or is, a principle provides an alternative point of departure for scientists who find contemporary materialist dogma lacking direction. De Anima, one of the most important books ever written, and long neglected by scientific psychology, still puts life in an eternal debate.