This chapter turns to Aquinas’s view that the human act is a hylomorphic composite. To discuss the human act’s hylomorphic structure, it first considers three power-exercises crucial to the execution of the human act once the choice has been made, namely, “command,” “use,” and the “commanded act.” It contends that the act of command is an act of reason that specifies the power by which a choice is to be executed. Use is a volitional act that activates, and sustains the exercise, of the power determined by command, and the commanded act is the exercise of this power. It then argues that use (rather than command) functions as the form of the commanded act by virtue of directing the latter to an end. The chapter draws on an insight from Chapter 4, arguing that formal and final causation coincide here, because what it is for a human act to be of a certain kind (and so to have a certain form) is for it to be directed to a certain end. The last section of this chapter discusses Aquinas’s account of how choice explains the hylomorphically organized human act, which relies on the notion of “virtual existence.”

The introductory chapter of this book offers a brief account of the relation between action theory and moral philosophy in Aquinas. It argues that Aquinas has a descriptive, metaphysical account of the human act, one that investigates the human act’s ontology as well as its aetiology, that is, respectively, what the human act is and how it is explained. This account brackets normative considerations about what acts are morally good or bad. The introduction specifies that the book deals with this descriptive theory, and it also motivates the book’s main textual focus, which is on one aspect of Aquinas’s Prima secundae discussion of the human act, namely, the phase leading from choice (electio) to the actual performance of the human act. Finally, the introduction states the main thesis of the book, which is that both choice and the human act that it explains are hylomorphically structured, for Aquinas. Choice is a composite of a volition and a preferential intentional structure inherited from a previous judgment, and the human act is a composite of a volition and a power-exercise caused by volition, such as a bodily movement.

This chapter turns to an examination of choice and its hylomorphic structure. To spell out this structure, it further investigates the formal-causal dependence relation between volition and judgment already considered in Chapter 4. It argues that Aquinas draws a distinction between two types of forms, a form extrinsic to the volition, which is the preceding practical judgment, and a form intrinsic to volition, which is the intentional structure that volition inherits from the preceding judgment. It furthermore suggests that the intentional structure of volition involves two components analogous to those present in judgment. There is an attitudinal component analogous to assent in judgment, which Aquinas refers to as “adherence,” and there is also a content adhered to, namely, a means as related to an end. The final section applies this general picture to choice to explain its hylomorphic structure. It argues that choice is a volition whose intrinsic form consists of an attitude of preferential adherence attaching to one means rather than another, where this form is an intentional structure derived from the previous judgment of choice.

This chapter applies the general hylomorphic theory of the human act to one of the two kinds of human acts that Aquinas countenances, namely, bodily human acts. In keeping with the general hylomorphic framework, it argues that a bodily human act is a composite of a volitional act of use and a bodily commanded act. This chapter investigates each of these two components and considers how they form one unified human act. It argues that while use is an immanent act, any bodily commanded is traunseunt. That is to say, use remains in the agent, while the bodily commanded act, which is an exercise of the “motive power” (vis motiva), comes to inhere in a patient external to the human body. What is more, it argues that use is an intrinsically instantaneous act, whereas any bodily commanded act takes time to be completed. On this basis, it concludes that use and the bodily commanded act are inherentially as well as durationally heterogeneous. The last section of the chapter examines whether this dual heterogeneity prevents use and the bodily commanded act from constituting a unified hylomorphic whole. It argue that this is not the case.

Having examined the judgment crucial to the hylomorphically structured act of choice, this chapter turns to the act of choice itself, which is a volition. It does not yet offer an account of choice’s hylomorphic structure but lays important groundwork for doing so in Chapter 5 by shedding light on Aquinas’s general account of volition and its dependence on judgment. It first argues that a volition differs from judgment because it involves a world-to-mind rather than mind-to-world direction of fit. It then examines how volition depends on judgment. Aquinas himself characterizes judgment as the formal as well as the final cause of volition. The chapter suggests that these are two descriptions of one and the same dependence relation: judgment orders volition to an end, which makes it a final cause, and in so doing it also determines the volition’s kind, which makes it a formal cause. The last two sections deal with Aquinas’s view that the will “moves itself.” They argue that this does not imply any freedom of the will to operate independently of reason. In short, the chapter advocates a strongly intellectualist account of the will’s freedom.

This chapter discusses Aquinas’s account of the freedom of the judgment of choice. It claims that, on his view, this judgment is free because it is up to us whether or not we assent to its propositional content, which Aquinas takes to be a means-end-relating precept. It examines what explains our ability to freely assent to a precept. It argues that this is explained by the logical structure of the precept that the agent assents to. In particular, the precept in question must fail to establish a necessary relation between a given means and the ultimate end. A precept fails to do this if it (1) relates an expedient, but non-necessary means to a non-ultimate end, or (2) a necessary means to a non-ultimate end, or (3) an expedient, but non-necessary means to the ultimate end. It also argues that the logical structure of the precept alone is not enough to guarantee our freedom of assent. An agent must also understand that a precept fails to establish a necessary relation between a means and the ultimate end in order to freely assent to it. To grasp this structure, the agent has to engage in a kind of higher-order judgment.

This chapter analyzes the key notion of the “human act” (actus humanus) around which Aquinas’s action theory revolves. It argues that, for Aquinas, the general term ‘act’ is used broadly to denote any power-exercise in nature, whether in the animate or the inanimate domain. Given this broad scope of the term ‘act,’ the chapter considers, in a next step, what sets human acts apart from other power-exercises. It argues that, according to Aquinas, one differentiating feature is that a human act is a hylomophically organized composite of two power-exercises, where a volition that he refers to as “use” is the formal component and a power-exercise caused by volition that he refers to as the “commanded act” is the material component. However, as the chapter also shows, Aquinas chiefly relies on an aetiological criterion to differentiate human acts from other power-exercises, arguing that a human act is explained by a preceding act of free choice. It then shows that choice likewise displays a hylomorphic structure, for Aquinas. It is a volition materially speaking, and its form is the preferential character that this volition inherits from a preceding judgment that Aquinas refers to as the “judgment of choice.”

This chapter applies the hylomorphic framework to the second general type of human act that Aquinas countenances, namely, mental human acts. In keeping with the general hylomorphic account, it argues that a mental human act is a composite of a volitional act of use and a mental commanded act. There are various mental powers that we can exercise at will, Aquinas thinks, including memory and the intellect. Aquinas’s most detailed account of a mental act performed at will concerns the act of “reminiscing,” by which Aquinas understands the deliberate attempt to retrieve a piece of information that has fallen from memory. The chapter argues that, in this human act, the component of use and the commanded component, which is an exercise of the power of memory, are both immanent. However, like the components of the bodily human act, they differ in their temporal unfolding. Use is intrinsically instantaneous, whereas the act of memory that it causes is temporally extended. The last section of this chapter considers Aquinas’s view that mental agency can be impeded by obstacles internal to the agent, such as mental illness.