Theoretical Medicine and Bioethics (2005) 26: 105–110
DOI: 10.1007/s11017-005-1235-9
Ó Springer 2005
ALFONSO GÓMEZ-LOBO
ON POTENTIALITY AND RESPECT FOR EMBRYOS:
A REPLY TO MARY MAHOWALD
ABSTRACT. In order to understand the nature of human embryos I first distinguish between active and passive potentiality, and then argue that the former is
found in human gametes and embryos (even in embryos in vitro that may fail to be
implanted) because they all have an indwelling power or capacity to initiate certain
changes. Implantation provides necessary conditions for the actualization of that
prior, active potentiality. This does not imply that embryos are potential persons that
do not deserve the same respect as actual persons. To claim that embryos ‘‘become
persons’’ is to understand the predicate ‘‘person’’ as a phase sortal, roughly equivalent to ‘‘adult person.’’ This entails that we would not be essentially persons. In
order to explain the traditional understanding of ‘‘person’’ as a proper sortal rather
than a phase sortal, the author distinguishes between proximate and remote
potentiality, and shows that, unlike feline embryos, human embryos, by their genetic
constitution, possess the remote potentiality to later exercise the typically human
activities. It follows that they are already persons essentially.
KEY WORDS: actual persons, embryo, gametes, phase sortal, potential persons,
potentiality, power, proper sortal
Professor Mary B. Mahowald has been kind enough to publish
extensive comments on a paper of mine that appeared in a recent
issue of this journal.1 I am both honored and grateful for her
remarks. In what follows I would like to offer some clarifications and
replies. Instead of quoting specific claims and addressing them
directly, I shall attempt to present an over-all treatment of the major
issues.
In trying to understand the beginnings of a human life, it is crucial
to distinguish between a sperm and an egg, the so-called ‘‘gametes,’’
on the one hand, and the organism that results from their fusion, i.e.
an embryo, on the other. One way to mark this distinction is by
focusing on their respective powers, i.e. on what they can and cannot
achieve given their nature.
It is clear that a sperm (or an egg), by itself, cannot develop into a
human adult. A single gamete simply does not have this power, even
if sustained by proper nutrients and conditions. An embryo, on the
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other hand, if given the proper conditions, certainly can reach
adulthood in the normal course of events.
One way of accounting for this difference is to say that a gamete
and an embryo have different potentiality. Since ‘‘power’’ and
‘‘potentiality’’ translate the same Greek word (dunamis) this is not to
say much, unless we explain what we mean by these terms. In a
rigorous philosophical sense, potentiality is a principle or source or
‘‘initiator’’ or ‘‘starter’’ (arche´ ) of change. We say that fire has the
power to burn a piece of wood and that a builder has the power or
capacity to build a house. This is usually referred to as ‘‘active
potentiality.’’ The wood and the bricks can be changed or set in
motion by the fire and the builder, respectively, and hence we say that
they are endowed with ‘‘passive potentiality.’’ The source of the
motion of the log and the brick is not within themselves. They do not
initiate their own metabolé or change.
What is typical of all forms of life, including gametes and embryos,
is that they are not primarily passive. Why not? Because what defines
passive potentiality is that the ‘‘activator’’ or principle of movement
is external to the thing. No external cause leads, say, a sperm to try to
force its way through the cumulus mass to reach the zona pellucida of
an oocyte. Nor is the oocyte in turn passive. This can be seen, inter
alia, in the spontaneous release of ‘‘degradative enzymes that allow
the sperm to penetrate the zona pellucida.’’2 All living things have
within themselves an active potentiality that scientists today view as
encoded in their genome.
It is true that a host of further external and internal conditions are
required for the activation of both active and passive potentialities,
but those conditions are not ‘‘activators.’’ They come close to what
we would call ‘‘necessary conditions.’’ In order for the fire to burn the
log, oxygen is required, but oxygen does not initiate the combustion.
As I have suggested, human embryos have an internal power or
potentiality that governs the morphogenesis and allows them to
develop into the complex organisms that we are at a later stage.
There cannot be any doubt that an embryo in vivo possesses the
specific potentiality encoded in the human genome, but an embryo in
vitro also has it. In fact, in vitro fertilization works on the assumption
that the active potentiality is present in the embryos that are selected
for implantation. If not, the procedure would not work. It is expected
that these embryos will initiate a host of ‘‘motions’’ or processes once
they are given the natural conditions found in a uterus. Of course,
embryos in vitro may be denied the normal external conditions for
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them to grow and develop, but this does not entail that their
potentiality is passive. The crucial external intervention of implanting
them does not make them live embryos of a given species. This is
something they already are.
Implantation, then, provides the vital conditions for an embryo to
develop, but it does not contribute to the potentiality in the strict
sense. The potentiality has to have been already present in the embryo for the embryo to implant. This can also be made clear by
pointing to the fact that no genetic material penetrates the embryo
after the initial zygote stage. This is not to minimize the enormous
importance of the interaction between mother and child, but to
clarify exactly what it consists in. The connection between a woman
and an embryo is literally of ‘‘vital’’ importance, so that if the latter is
deprived of the natural environment provided by the mother either
due to a miscarriage, to abortion, or through failure to implant, it
cannot continue to live. The possibility of the embryo reaching full
maturity and birth, then, depends on the mother, but her enormous
and generous contribution should not be confused with the indwelling active potentiality of the child.
Let us return for a moment to the gametes and emphasize that
they do not have passive potentiality like the log or the bricks. As
we saw, they are ‘‘initiators’’ of various processes when they meet,
but what is the ultimate outcome of those ‘‘motions’’? They are
steps toward the generation of a zygote, a point of arrival that
entails the demise of the gametes themselves. In metaphysics this
would be called a ‘‘substantial change.’’ By contrast the internal
division of the zygote into two cells, the formation of the morula,
the compaction of the blastomeres, etc. are all instances of alteration of the same substance.
The process that the gametes initiate when they meet and the
process that the embryo initiates on its own are thus quite different.
We are therefore entitled to conclude that the potentiality that causes
those changes is also different. In my original article this conclusion
was meant to show that there is no valid logical step from the
potentiality of an embryo to the potentiality of the gametes.
What do these metaphysical considerations imply for ethics? First
that gametes are so different from embryos that respect for embryos
in no way requires respect for gametes. By ‘‘respect’’ I meant in the
original article something very basic: that it would be morally wrong
intentionally to destroy them. I did not pretend to include attenuated
forms of respect, such as the respect with which one should treat
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one’s parents or one’s elders. Respect in my paper was meant to be
understood as the correlate of strict inviolability.
As a matter of care, I agree ‘‘that embryos should be treated as
embryos and not, for example, as newborns or adults.’’3 Proper care
of embryos probably entails that they should be implanted, just as
newborns should be fed, and adults, when sick, should be taken to the
doctor. But as a matter of respect, it would be discrimination on the
basis of age to claim that a human being at any of these stages is
devoid of inviolability, and may be used as resource material for
other ends.
Shouldn’t we say, however, that adults are ‘‘actual persons’’
whereas embryos and newborns, and young children are ‘‘potential
persons’’ and as such not ‘‘deserving of the same respect we tender to
actual persons?’’ If this is the case, wouldn’t they be at our disposal if
we think that ‘‘their destruction is necessary to save the life of an
actual person?’’
I would like to address these questions by revisiting the issue whether
personhood is a phase sortal or a proper sortal. As the reader of my
original paper might recall, the former stands for a concept under which
an object falls during a stage of its existence, the latter a concept such
that if an object ceases to fall under it, that object ceases to exist.
What follows if personhood is a phase sortal? First, it follows that
just as we go through the teenage stage, we would go through the
person stage. The latter may be longer, but equally accidental (in the
metaphysical sense of the term). Just as we are not essentially teenagers, we would not be essentially persons. Since this entails the
apparent absurdity that we are not essentially conscious and
self-conscious rational beings (for these are among the defining features of persons), some critics shift their ground at this point and hold
that personhood does indeed stand for a proper sortal, that we are
essentially persons. It then follows that we started to exist only when
our decisive substantial change into conscious beings occurred. It is
notorious, however, that there is no empirical evidence during pregnancy or child growth that would allow us to identify the point at
which the drastic change that would mark the beginning of our
existence took place. The features that are taken to be characteristic
of persons emerge gradually in a child that already exists and continues to exist. She does not undergo ‘‘generation’’ (starting to exist),
but rather ‘‘alteration’’ (a change in properties). This justifies the
apparent plausibility of referring to children as ‘‘potential persons.’’
But talk of embryos or children ‘‘becoming persons’’ requires that
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‘‘person’’ be understood once again as a phase sortal, that is, as
denoting what these individuals that already exist are going to be
during later stages of their lives. It seems clear that we are going
around in circles.
I will try to explain how the aforementioned conundrum arises.
Any concept of personhood presupposes the notion of potentiality.
No one can think and act uninterruptedly. We sleep (and we are
sometimes under anesthesia) without ceasing to be persons. So a
person is a being that has the capacity to reason, to engage in selfmotivated activity, to communicate, to act as a moral agent, etc. This
capacity is a proximate potentiality to engage in those types of
activity, and in normal adults it can be activated at will. In most
people’s usage ‘‘person’’ really means ‘‘adult person.’’
Any proximate potentiality, however, is an activation of a more
remote potentiality. The capacity to speak Spanish that some people
can activate at will is in turn an activation of the more remote
capacity to learn a language. A child (who was before that a baby,
and before that a fetus, and before that a human embryo) has the
remote potentiality to learn languages. This is part of what it means
to be human. A feline or canine embryo does not have this potentiality. It is not part of its essence.
There is doubtless a decisive difference between human embryos
and embryos of other natural kinds, and the best way to express that
difference is by reference to their respective remote potentialities.
Human embryos already have the remote potentiality to learn languages, to think, to act, etc. Normal development will later lead to
the activation of those capacities and hence to the establishment of
proximate capacities.
In the Western philosophical and theological tradition personhood has always been associated with remote or essential potentiality, not with proximate capacity. Thus, an existing organism
cannot ‘‘become a person.’’ It is either a person already or it is not,
and this is determined by its very nature. The different capacities
that a person possesses may not yet be susceptible of activation on
demand, and in this sense there is much that is present only
potentially in a person at the early stages. Accordingly, no human
being is ‘‘a potential person.’’ A human being of any age is actually
a person who has a host of remote and proximate potentialities.
They are grounded in his or her essence. And this holds for an in
vitro embryo as well.
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NOTES
1
Alfonso Gómez-Lobo, ‘‘Does Respect for Embryos Entail Respect for Gametes?’’
Theoretical Medicine and Bioethics 25 (2004): 199–208; Mary B. Mahowald,
‘‘Respect for Embryos and the Potentiality Argument,’’ Theoretical Medicine and
Bioethics 25 (2004): 209–214.
2
W.J. Larsen, Essentials of Human Embryology (New York: Churchill Livingstone,
1998), pp. 12–14.
3
cf. Mahowald, cited in n.1, above: 211.
Department of Philosophy
Georgetown University
37th and O Streets, N.W.
215 New North
Washington DC. 20057
U.S.A.
E-mail: [email protected]