Peter of John Olivi on the Psychology of Animal Action

1. Introduction

Peter of John Olivi (ca. 1248–98) is one of the most significant thirteenth-century authors. Recent studies have shown that his revolutionary conception of the freedom of the will is a turning point in medieval philosophical psychology and that his theory of cognition is original and philosophically highly interesting.¹ Olivi is sometimes depicted as a spiritualist theologian, who is interested in philosophical questions only when they bear theological relevance, and whose philosophical discussions are mainly aimed at showing that philosophy cannot arrive at definite truths.² Although there is certainly some truth in this view, a larger perspective on Olivi’s philosophical psychology shows that he was interested in psychological issues for their own sake.

The ultimate aim of this essay is to clarify Olivi’s remarks concerning the appetitive powers of the sensitive soul. In order to achieve that goal, I will have to expound on his views on all the psychological capacities that are necessary for animal action. It needs to be emphasized that by discussing nonhuman animals I am not excluding human beings; rather, I examine the capacities that Olivi conceives of as belonging to both human beings and nonhuman animals. He is not original in his interest in animal psychology. Virtually all the medieval authors who wrote on psychological questions—even those with primarily theological motivations— discussed also the powers of the animal soul, and usually they saw only minor differences between human beings and nonhuman animals with respect to them.³ Although Olivi does not value animals highly, he thinks that human beings are psychologically similar to nonhuman animals in many respects. In a famous passage, Olivi says that without the freedom of the will, human beings would be mere “intellectual beasts.”⁴ Yet his conceptions of the psychological functions that are common to human and nonhuman animals have not been studied hitherto.

An examination of Olivi’s understanding of the psychology of animal action shows that he is interested in psychological issues even when they are not relevant for theology. He deviates from certain influential ideas of Avicennian-Aristotelian psychology for philosophical reasons,⁵ and although his approach to animal psychology is partly inspired by Augustine’s fragmentary remarks, he develops his views in the general framework of medieval faculty psychology and discusses ideas that are not received from Augustine. One of the most interesting ideas that Olivi discusses is related to appetitive powers, which are connected to the external senses. Even though his discussion remains sketchy, it seems that these powers are meant to account for the bodily nature of our needs and desires, and to explain how the emergence of action is related to the bodily state of the subject.

In order to make Olivi’s view concerning the appetitive powers of the soul intelligible, I will have to cover a wide range of his ideas concerning animal psychology. Section 2 gives a broad outline of the elements that are necessary for nonrational action, namely, perception, estimative evaluation, emotion, and an appropriate bodily state of the subject. After this general outline, I will consider first the cognitive side of the psychological process behind action. In section 3, I will discuss certain important aspects of Olivi’s theory of perception, and section 4 is devoted to the evaluative aspect of perception.

The rest of the essay analyzes Olivi’s view on appetitive aspects of animal psychology. In section 5, I will take up the idea that every cognitive power of the soul includes also an appetitive power, and section 6 shows that Olivi argues for this view because he thinks that otherwise certain psychological phenomena—such as pain and pleasure—cannot be accounted for. The role of the appetitive powers of the soul is discussed further in section 7, where Olivi’s idea of the relation between changing bodily states, desires, and needs is analyzed. Finally, section 8 arrives at an interpretation in which various aspects of Olivi’s view on the psychology of animal action are brought together.

2. Psychological Processes Behind Action

The most complex psychological operations that...