Francis Beckwith writes the following description of the substance view of persons in his book, Defending Life: A Moral and Legal Case Against Abortion Choice:
According to the substance view, a human being is intrinsically valuable because of the sort of thing it is and the human being remains that sort of thing as long as it exists. What sort of thing is it? The human being is a particular type of substance - a rational moral agent - that remains identical to itself as long as it exists, even if it is not presently exhibiting the functions, behaving in ways, or currently able to immediately exercise these activities that we typically attribute to active and mature rational moral agents.1
He goes on:
Another way to put it is to say that organisms, including human beings, are ontologically prior to their parts, which means that the organism as a whole maintains absolute identity through time while it grows, develops, and undergoes numerous changes, largely as a result of the organism's nature that directs and informs these changes and their limits. The organs and parts of the organism, and their role in actualizing the intrinsic, basic capcities of the whole, acquire their purpose and function because of their roles in maintaining, sustaining, and perfecting the being as a whole. This is in contrast to a thing that is not ontologically prior to it parts, like an automobile, cruise ship, or computer. Just as a sporting event (e.g., a basketball game, a golf match) does not subsist through time as a unified whole, an automobile, ship, or computer does not as well. It is, rather, in the words of Moreland, "a sum of each temporal (and spatial) part." Called mereological essentialism (from the Greek "meros" for "part"), it "means that the parts of a thing are essential to it as a whole; if the object gains or loses parts, it is a different object." Organisms, however, are different, for they may lose and gain parts, and yet remain the same thing over time.2
Do you hold to this view of persons? If so, why or why not? Feel free to weigh in in the comments below.
Stand firm in Christ,
1. Page 132
2. Page 133