Winter 2005

Agere sequitur esse: What Does It Mean? A Reply to Father Austriaco

David L. Schindler

"Austriaco defines being not by what it is, but by what is its first (ontological) effect."

Father Nicanor Austriaco concludes his article, “Are Teratomas Embryos or Non-Embryos? A Criterion for Oocyte-Assisted Reprogramming,”1 with a strong criticism of “A Response to the Joint Statement, ‘Production of Pluripotent Stem Cells by Oocyte Assisted Reprogramming’”2 for reasons similar to those advanced by E. Christian Brugger in the present number of Communio. An examination of Austriaco’s criticism will help clarify further the fundamental question raised by ANT-OAR: what properly defines an organism (embryo), and by what criteria do we distinguish an organism from a non-organism? Of crucial significance here is the Aristotelian-Thomistic axiom, agere sequitur esse, and indeed the Aristotelian-Thomistic notion of substance (hylomorphism). Austriaco invokes this axiom as the foundation for the central claim of the OAR proposal: “we can reasonably and with certitude conclude that an OAR-generated entity that becomes a tumor is ontologically different from an embryo, because its different organization and behavior shows that it has a different nature. Again, agere sequitur esse” (706; emphasis added). In other words, radical disorganization (absence of coordinated interaction of parts) in an OAR-generated entity leads reasonably and with certitude to the conclusion that this entity is not and was not in its original constitution an embryo, but only a tumor. “This is not an argument derived from a flawed mechanistic philosophy. This is an argument grounded in the Aristotelian- Thomistic axiom, agere sequitur esse” (706).

We will evaluate Austriaco’s claim of certitude regarding the product generated by ANT-OAR, and his criticism of the “Response to the Joint Statement,” relative to his reading of this Thomistic axiom which, by his own express acknowledgment, undergirds both the certitude and the criticism.


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1. Nicanor Pier Giorgio Austriaco, O.P., “Are Teratomas Embryos or Nonembryos?” National Catholic Bioethics Quarterly 5 (Winter 2005): 697–706.

2. David L. Schindler, “A Response to the Joint Statement, ‘Production of Pluripotent Stem Cells by Oocyte Assisted Reprogramming,’” Communio 32, no. 2 (Summer 2005): 369–380.