In this text, James deals with the question of whether the will moves itself. In order to examine this question, he thinks it necessary to first develop a theory of the soul’s powers in general. At the heart of this general theory is a (then) unorthodox view about the granularity of the powers of the soul. James thinks that there are, in addition to our generic powers to think and see, a myriad of fine-grained powers in the soul, such as the power to think about cathood or the power to see red. James does not venture to say just how fine-grained these powers are, claiming that only God knows this. Drawing on terminology due to Simplicius, he calls a generic or coarse-grained power of the soul a “general aptitude” (idoneitas generalis), while he calls a fine-grained power a “special aptitude” (idoneitas specialis). James also argues in this text that an aptitude, whether general or special, is an “incomplete act”. By characterizing a power as an incomplete act, James is claiming that it is an incomplete version of the operation that it can bring about. So, for example, Socrates’ aptitude to think about cathood is an imperfect version of his act of thinking about cathood.

The rodent somatic sensory system is characterized by a prominent representation of the mystacial vibrissae, which form an orderly array of low-threshold mechanoreceptors. Centrally, the arrangement of the vibrissal pad is maintained in arrays of cellular aggregates referred to as barrelettes (brainstem), barreloids (thalamus), and barrels (primary sensory cortex). Trigeminal brainstem nuclei that receive vibrissal primary afferents give rise to two main streams of information, the lemniscal and paralemniscal pathways. The lemniscal pathway arises from the trigeminal nucleus principalis, transits through the ventral posterior medial nucleus of the thalamus, and projects to the primary somatosensory cortex. The paralemniscal pathway arises from the rostral part of trigeminal spinal nucleus interpolaris, transits through the posterior group of the thalamus, and projects to the somatosensory cortical areas and the vibrissa motor cortex. In this chapter, we review the anatomical organization of these pathways and propose that whereas the lemniscal pathway encodes both touch and whisking kinematics, the paralemniscal pathway signals the valence of orofacial inputs. Lastly, we call attention to the importance of understanding sensory processing in the brainstem trigeminal nuclei to understand their role in regulating behavior. These nuclei are richly interconnected and contain inhibitory circuits that operate both pre- and postsynaptically.

Aquinas thinks that not all instances of efficient causation are equivalent. Certain instances of efficient causation, namely per se cases, are the most fundamental and proper. Other instances of efficient causation happen in virtue of these cases. The chapter reconstructs Aquinas’s views on per se efficient causation. The chapter next examines Aquinas’s views on the temporal and modal relationship that obtains between per se natural efficient causes and their effects. The chapter shows that Aquinas thought that per se causes are simultaneous with their effects. Contemporary scholars debate whether Aquinas thought that natural efficient causes necessitate their effects. The chapter brings greater clarity to Aquinas’s views by examining his distinctions between different types of natural efficient causes and different types of necessity. Finally, the chapter considers Aquinas’s views on important relational conditions for efficient causation: the agent and the patient must be distinct and they must be in contact with each other. The chapter analyzes Aquinas’s arguments against self-motion and action at a distance.

In DA I.2–5, Aristotle offers a series of critical discussions of earlier Greek definitions of the soul. The status of these discussions and the role they play in the justification of Aristotle’s theory of soul in DA II–III is controversial. In contrast to a common view, I argue that these discussions are not dialectical but philosophical. I also contend that Aristotle does not consider earlier philosophical definitions of soul to be endoxa, but rather contradoxa – beliefs about which the many and the wise disagree among themselves. Through an analysis of Plato’s and Empedocles’s definitions of soul, I show that these definitions are nevertheless treated by Aristotle as potential scientific principles for explaining two of the soul’s per se attributes: causing motion and cognition in animate bodies. The main role of the critical discussions in DA I.2–5 is to show that all such earlier definitions of soul fail this explanatory task. Nevertheless, I show that these chapters are not wholly aporetic. Aristotle makes progress by solving two scientific puzzles within them: whether the soul has spatial parts, and whether ‘soul’ refers to a uniform entity across biological species.

This chapter sets out to explore the thesis that Plato, at least in his later years, in his efforts to identify the nature of his First Principle, was inclined to settle on the concept of a rational World Soul, with demiurgic functions, and that this was a doctrine that his faithful amanuensis in his last years, Philip of Opus, advanced on his own account, in the belief that in this he was developing the latest theories of his Master.

The chapter offers a brief discussion of Aristotle’s theory of animal self-motion and the conception of animal agency this theory implies. I start with a description of the philosophical problem Aristotle faces in accounting for animal self-motion. His solution to that problem, I argue, lies in a biological conception of the soul as the unmoved mover of the animal’s self-motions. His theory, I further argue, includes a biological account of desire as a process that may be described as a homeostatic mechanism of self-preservation on the level of perceivers. I then turn to the resulting conception of animal agency. Here I argue that Aristotle regards animals as self-movers insofar as they appropriate, and redirect, the energy they receive from the environment for their own purposes and in accordance with how they perceive things in the world. An Aristotelian account of the causation of an episode of animal self-motion will thus have to include reference to how things appear to the animal. I end the chapter with a brief discussion of the relation of Aristotle’s biological account of animal self-motion to his account of (rational) human self-motion.