Chapter seven addresses the difficulty of the theological interpretation of evolutionary biology in delineating a precise account of the concurrence of divine and contingent causes engaged in speciation. Invoking Aquinas’s famous distinction between God’s primary and principal causation and the secondary and instrumental causation of creatures, a constructive model of the concurrence of divine and natural causes in evolutionary transformations is offered.

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.”