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Introduction to Philosophy
Part III. Thomas Aquinas, "The Argument from Necessity"
Abstract: Thomas' Argument from Necessity
is outlined and explained. He argues that since all existent
things depend upon other things for their existence, there must
exist at least one thing that is a Necessary Being. Some standard
objections to that argument are also briefly
discussed.
- Thomas' Argument from Necessity begins with a number of empirical
observations including the premise that contingent objects in
the world come into existence and pass away. The argument is an
à posteriori argument, and the conclusion is not
claimed to follow with certainty.
- The Argument from Necessity:
- Since objects in the universe come into being and pass
away, it is possible for those objects to exist or for those
objects not to exist at any given time.
- Since objects are countable, the objects in the universe
are finite in number.
- If, for all existent objects, they do not exist at some
time, then, given infinite time, there would be nothing in
existence. (Nothing can come from nothing—there is no
creation
ex nihilo)
for individual existent objects.
- But, in fact, many objects exist in the universe.
- Therefore, a Necessary Being (i.e., a Being of which
it is impossible that it should not exist) exists.
- The concepts of necessary and contingent are essential
concepts in the history of philosophy. Some examples
illustrating a few of the difficulties of these concepts
are as follows.
- One way to think about Thomas' argument is to consider
a straight line extending without bound representing time.
If one takes a finite number of line segments of
a specific length representing the time of existence of
objects in the world and places them on that line, then most
of the unbounded time-line would be unoccupied. That is,
very little of the time would objects exist. Thus, there
must be something necessary upon which these existent
objects depend since at the present time it would so
improbable that objects should exist.
- Although the Argument from Necessity is empirical, the
concepts of necessary and contingent are logical. The crucial
question is in Hume's words, whether matters of fact are being
confused with relations of ideas in the argument.
- If objects in the world are being constantly generated,
does this fact imply that God is necessary for their individual
existence? Would it then follow that the sequence of time
is a sequence of miracles, since the occurrence of events
would no longer be subject to the laws of nature? Is God
"necessary" for all existent things individually or
for all existent things in toto or for just the first
existent thing? With God as necessary existence, how can we
rule out Russell's Five Minute
World Hypothesis using the principle of simplicity?
- Summary list of common objections to Thomas' Argument from Necessity:
- The fact that many things exist when, if the argument were
correct, the probability of objects existing is
self-refuting since being must exist at the same time
as these arguments in order to evaluate such arguments.
- If God is an existent object in the universe, then by
premise (1), it is possible for God not to exist. If God
is a different kind of existent thing, then the
argument commits the fallacy of petitio
principii or the circularity of assuming in
the premises what is to be proved.
- The premise "If, for all existent objects, they do
not exist at some time, then, given infinite time, there would
be nothing in existence" commits the fallacy of
composition. Simply because the parts of a group are
limited, it does not follow that the group as a whole is
limited. The properties of whole do not necessarily exhibit
the properties of the parts. Simply because all human beings
have a finite life-span, it does not follow logically that
someday the human race will come to an end— unless,
of course, additional assumptions are made. Moreover, in
Aristotelian philosophy, the corruption of one being is the
generation of another—nothing ceases to exist without
the generation of something else.
- Necessity is a property of statements not of objects.
It doesn't make sense to claim that an existent thing is logically
necessary. Existent things just are, that's all. We have no
examples of necessary existence; we just have examples of
necessary inferences or judgments. There can be no empirical
necessities.
- As Kant notes, existence is not a real predicate or
property; existence is not a characteristic which can be
added to the concept of the subject. Thus, the concept
of necessary existence is not meaningful. (Q.v.,
the notes Existence Is Not
a Predicate)
- The idea of necessary being is unintelligible. As
Hume point out, any statement concerning existence can be
denied. Hume writes, "The words, therefore "necessary
existence," have no meaning, or which is the same thing,
none of which is consistent." Whatever we can conceive
as existent, we can also conceive as nonexistent.
- Nevertheless, Charles Hartshorne claims that the predicate
"necessary existence" does add something the
concept of God and so is a real predicate or property. E.
g., "necessary existence" is distinguished from
contingent existence in that necessary existence cannot
not exist.
- Problem with Creation ex nihilo. Thomas'
statement of our premiss (3) that nothing can come from nothing
is expressed by him this way: "…that which does
not exist begins to exist only through something
already existing." This premise implies that the newly
existent thing is only a transformation of the already existing
thing; otherwise, there would be no way to account for the newly
existing thing given the truth of the principle of the
conservation of matter and energy. If Aquinas were to deny
the principle of the conservation of matter and energy, then
he would be tacitly denying the principle of creation ex
nihilo for contingent things.
- Thomas' does seem to presuppose the principle of the
conservation of matter (and tacitly, anything equivalent
to matter) in the implicit assumption that the universe
is limited.
- As reasonable as this assumption appears to be, consider
Stephen Hawking's
explanation of creation of matter and energy:
- Where did they [i.e., 1080 particles
in the universe] all come from? The answer is that,
in quantum theory, particles can be created out
of energy in the form of particle/antiparticle pairs.
But that just raises the question of where the energy
came from. The answer is that the total energy of the
universe is exactly zero. The matter in the universe is made
out of positive energy. However, the matter is all
attracting itself by gravity. Two pieces of matter
that are close to each other have less energy
than the same two pieces a long way apart, because
you have to expend energy to separate them against the
gravitational force that is pulling them together.
Thus, in a sense, the gravitational field has negative
energy. In the case of a universe that is approximately
uniform in space, one can show that this negative gravitational
energy exactly cancels the positive energy represented by
the matter. So the total energy of the universe is zero.
- The physicist Heinz Pagels
speculates, "Maybe the universe itself sprang into
existence out of nothingness—a gigantic vacuum fluctuation
which we know today as the big bang. Remarkably, the laws
of modern physics allow for this possibility."
- Problem of Criterion of Counting. Are space and
nature continuous or discrete? Where does one object end and
another begin? Is a fist made from a closed hand something or
nothing? Where does the fist go when the hand is opened?
Where does a lap go when one stands up? In premise (2) there
is a serious problem of criterion of counting objects
and their parts. How could Thomas handle these and similar
examples?
- Problem of the Ultimate Consistent of the Universe.
Ultimately is nature continuous or discrete? Do we have
any good reasons for assuming with Thomas that nature is discrete
rather than continuous?
- As Hume points out in his Dialogues, nature, the
universe itself, or something else could qualify as just as
much a "necessary being" as God would. Why would
we suppose that there could just be one necessary being in
the universe?
Further Reading:
- “Necessity”
Stephan Kürner outlines the various conceptions of necessity in
science and philosophy, including both the notions of logical and
substantive necessity in the Dictionary
of the History of Ideas maintained by the Electronic Text
Center at the University of Virginia Library. Emphasis is placed on
early Greek philosophy, Christian theology, modern science,
rationalism, empiricism, Kant, Hegel, Marx, and twentieth-century
views.
- God
and Other Necessary
Beings An analysis of concrete and abstract entities which cannot
fail to exist by Matthew Davidson in the Stanford Encyclopedia of
Philosophy. Emphasis is placed on the seach for grounds for
truth of necessary existence.
- Necessity This
discussion of logical, philosophical, and theological necessity
including descriptions of metaphysical, physical, and moral necessity
is an entry in the Catholic Encyclopedia.
“Given the theistic view of creation ex nihilo the
theist must deny that the universe can be a metaphysically necessarily
existent being whose necessity is caused of itself. If
the universe or parts of it, do exist necessarily, then it
has its necessity from another necessary being, God who has its
necessity of itself.” Michael Philip Levine, Pantheism
(London: Routledge, 1994), 252-253.
Relay corrections, suggestions or questions to
larchie at lander.edu
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This page last updated 01/27/24
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