Thomas Aquinas and the Generation of the Embryo

200 Pages·2015·0.6 MB·English

Thomas Aquinas and the Generation of
the Embryo: Being Human before the
Rational Soul
Author: Melissa Rovig Vanden Bout
Persistent link: http://hdl.handle.net/2345/bc-ir:104090
This work is posted on eScholarship@BC,
Boston College University Libraries.
Boston College Electronic Thesis or Dissertation, 2013
Copyright is held by the author, with all rights reserved, unless otherwise noted.
Boston College
The Graduate School of Arts and Sciences
Department of Philosophy
THOMAS AQUINAS AND THE GENERATION OF THE EMBRYO
BEING HUMAN BEFORE THE RATIONAL SOUL
a dissertation
by MELISSA ROVIG VANDEN BOUT
submitted in partial fulfillment of the requirements
for the degree of
Doctor of Philosophy
December 2013
© copyright by MELISSA ROVIG VANDEN BOUT
2013
Abstract: “Thomas Aquinas and the Generation of the Embryo: Being Human before the
Rational Soul”
By Melissa Rovig Vanden Bout
Peter Kreeft, Adviser
Thomas Aquinas is generally viewed as the chief proponent of the theory of
delayed animation, the view that the human embryo does not at first have the rational
soul proper to human beings. Thomas follows Aristotle’s embryology, in which an
embryo is animated by a succession of souls. The first is a nutritive soul, having the
powers of growth, nutrition, and generation. The second is a sensitive soul, having the
additional powers of locomotion and sensing. The third and final soul is the human, or
rational soul, which virtually includes the nutritive and sensitive souls. Because Thomas
holds that there is only one substantial form of a composite, none of these forms overlap
to provide continuity. It is therefore exceedingly difficult to speak of the embryo as one
enduring subject through the succession of souls. Moreover, because of the way that the
nutritive soul is associated with plants, and the sensitive soul is associated with animals,
interpreters generally hold that for Thomas the embryo is first a plant, then an animal,
and with the advent of the rational soul, finally a human being.
Those who write about the ontological status of the embryo assume that delayed
animation necessarily entails delayed hominization, that is, that the embryo only becomes
human at a later stage of its development, when it receives the rational soul. Those who
hold a delayed animation view of the embryo often invoke Thomas’ schedule of
successive souls in the embryo as a model for viewing it as not yet human in early stages
of development, linking hominization to the ability to perform intellectual operations.
That Thomas specifies that a body must be sufficiently organized before the advent of the
rational soul seems to them to solidify their view of the embryo as not sufficiently
organized to be truly human. Additionally, even outside of an explicitly Thomist
framework, Thomist metaphysical principles are often invoked in arguments that center
on twinning and totipotency of blastomeres in the early embryo, and whether that early
embryo is one individual if it is potentially many. Those who hold immediate animation
views (i.e., the embryo receives the rational soul at once, with no mediate states) often
adopt the strategy of importing modern data on the internal organization and self-directed
development of the embryo, and argue that if only Thomas had known that the zygote
was not unformed and undifferentiated, that it has within itself all it needs to become a
mature adult human, he would have held that the embryo is immediately suited to receive
the rational soul, and thus is human from conception. In this way they attempt to employ
a change in scientific data to negate the need for a succession of forms in the embryo.
The author identifies the being of the human embryo as a prior metaphysical
problem within Thomas’ work, and advances a different interpretation of his views: that
the embryo, even before the advent of the rational soul, is human. To establish this claim,
she traces the problems which emerge in the current debate about when the embryo
becomes human, and argues that contrary to expectation, it is not necessary to equate
immediate rational animation with immediate hominization, demonstrating that all other
approaches yield results entirely untenable for Thomas. A survey of texts reveals that
Thomas did in fact view the embryo as human before the rational soul, though he does
not methodically work out the implications of that view in a number of areas. Moreover,
a distinction based on a passage in Aristotle’s Generation of Animals with regard to an
additional meaning of generation may resolve the ambivalence in Thomas’ account of the
embryo as passive under the formative power of the father’s semen. Finally, a third
meaning of generation is offered to show that Thomas recognized and wished to resolve
the difficulty of explaining the continuity and identify of the embryo in the succession of
souls. What results is an immediate hominization view of the embryo that, because it
accommodates Thomas’ succession of souls and does not depend upon importing modern
biological data on the embryo, is consistent with Thomas’ account, and is thoroughly
cognizant of the way Thomas viewed human nature and the final end of human being.
for all my babies,
from Joy and Luke to Jenna and Samantha
TABLE OF CONTENTS
CHAPTER 1: THE HUMAN EMBRYO AS A PHILOSOPHICAL PROBLEM......1
INTRODUCTION...........................................................................................................................................1
THOMAS AND THE DEBATE:THESOUL OF THE EMBRYO............................................................................4
CONTEXT FOR THOMAS’TREATMENT OF THE EMBRYO............................................................................11
CHAPTER 2: SILLY SCIENCE AND FAULTY PHILOSOPHY............................17
ROOTS OF MODERN DELAYED ANIMATION POSITION..............................................................................17
SILLY SCIENCE:THEEMBRYO AS HOMUNCULUS.....................................................................................18
THOMAS AQUINAS AS THE MODEL FOR DELAYED ANIMATION................................................................20
FAULTY PHILOSOPHY:MAN AS TWO SUBSTANCES V.MAN AS A HYLOMORPHIC UNITY.........................24
RECAPITULATION AND FURTHER DEVELOPMENTS OF THE MODERN DELAYED ANIMATION POSITION....27
ANTICIPATION OF LATER ARGUMENTS.....................................................................................................33
ACRITIQUE OF DELAYED ANIMATION, ON FAMILIAR GROUNDS.............................................................38
AFURTHERPROBLEM:MISTAKING ‘LOOK’ FOR BEING............................................................................41
CHAPTER 3: INDIVIDUALITY OF THE EMBRYO AND OTHER TECHNICAL
DISPUTES.......................................................................................................................48
OVERVIEW................................................................................................................................................48
TWINNING................................................................................................................................................50
TOTIPOTENCY...........................................................................................................................................52
WHENDIDIBEGIN?.................................................................................................................................58
OTHERVOICES IN THE DEBATE................................................................................................................61
TOTIPOTENCY REVISITED.........................................................................................................................63
TWINNING,AGAIN....................................................................................................................................70
WEIGHING THE OPTIONS..........................................................................................................................75
CHAPTER 4: IMMEDIATE ANIMATION, EFFICIENT CAUSALITY, AND
POTENTIALITY............................................................................................................77
ORGANIZATION IN THE EMBRYO..............................................................................................................80
THEN AND NOW, THE SCIENCE OF EFFICIENT CAUSE...............................................................................88
POTENTIALITY..........................................................................................................................................93
SPERM AS A POTENTIAL PERSON..............................................................................................................97
POTENCY V.POSSIBILITY V.PROBABILITY.............................................................................................100
MEDIATE CONCLUSIONS........................................................................................................................102
CHAPTER 5: “X” MARKS THE SPOT....................................................................106
CHAPTER 6: “SUMMA” KIND OF ARGUMENT, WITH A DIFFERENT
QUESTION...................................................................................................................119
FIRSTARTICLE.......................................................................................................................................121
WHETHER THE EMBRYO IS A BEING AT ALL?..........................................................................................121
SECONDARTICLE...................................................................................................................................123
WHETHER THE EMBRYO BELONGS TO A GENUS BUT NOT A SPECIES?......................................................123
THIRDARTICLE......................................................................................................................................125
WHETHER THE EMBRYO IS BECOMING HUMAN?......................................................................................125
FOURTHARTICLE...................................................................................................................................127
WHETHER THE EMBRYO IS HUMAN BEFORE THE ADVENT OF THE RATIONAL SOUL?................................127
CHAPTER 7: BACK TO THE BEGINNING WITH THOMAS............................130
THESEMINAL POWER.............................................................................................................................132
GENERATION AND CORRUPTION.............................................................................................................137
THE‘INFANT’ IN THE WOMB..................................................................................................................141
EXCEPTIONAL CONCEPTIONS.................................................................................................................142
THE‘IMPERFECTION’NATURAL TO INFANTS AND YOUNGCHILDREN....................................................147
MAN AS GENERATED, NOT CREATED.....................................................................................................150
CHAPTER 8: FINAL END, NATURE, AND THE MEANINGS OF GENERATION
.........................................................................................................................................153
NATURE AS INTERNAL............................................................................................................................157
THE“HEART” OF THE MATTER...............................................................................................................159
DISTINGUISHING BETWEEN DIFFERENT MEANINGS OF GENERATION......................................................171
CHAPTER 9: A THOMIST ACCOUNT OF THE EMBRYO................................173
THERATIONAL SOUL.............................................................................................................................178
GOD AND PARENTS COOPERATING IN GENERATION...............................................................................179
SPARROWS:EMBRYOSBEFORE RATIONAL ENSOULMENT......................................................................182
PERSONHOOD:THEEMBRYO AND THE SEPARATED SOUL......................................................................184
1
“Until the fetus has a human soul, it is not a human being…”
-Robert Pasnau1
Chapter 1: The Human Embryo as a Philosophical Problem
Introduction
At one point or another, we have all wondered about the beginnings of human
life. It seems almost magical: a male releases semen in a fertile female, and if all goes
well, mere weeks later she notices that her body is changing in a thousand subtle (and not
so subtle) ways. In another few months she can feel movement in her body that is not of
her body but of another. A few more months, and she gives birth to an infant. We now
know considerably more than we used to about what occurs between coitus and birth, but
even with all of our high powered microscopes, with IVF and cloning and 3-D
ultrasounds which reveal whether baby has inherited the family nose, we are no closer to
a consensus about when human life begins. In fact, it seems that the more we understand
the minutia of the mechanisms of conception and embryonic development, the more we
contest the what and when of that which has been conceived. As Norman Ford puts it in
the title of his book, “When did I begin?”2
1Thomas Aquinas on Human Nature: A Philosophical Study Of Summa Theologiae 1a, 75-89, (Cambridge,
U.K. : Cambridge University Press, 2002), 109.
2 Norman M. Ford, When Did I Begin? Conception of the human individual in history, philosophy and
science, (Cambridge: Cambridge University Press, 1988). Our overwhelming concern, of course, has not
generally been to find out when each of us began, but at what point we must treat the new, growing
organism as a person in moral and legal contexts. We have sometimes asked about what it means to be
human, but usually only with regard to embryonic states or perhaps the existence of those near death or not
manifesting certain ‘human’ attributes such as sentiency. It seems to me a very strange thing to limit a
discussion about beginnings and endings and human nature to the very extremes, as if the bulk of human
living were indifferent to the meaning of human existence, and as if human life, whenever it begins and
wherever it ends, were not all “of a piece.”