Thomas Aquinas, “The

II. In order to appreciate the cogency of

Thomas's five arguments for God's existence,
some of the scientific concepts upon which his
Five Ways” arguments are based are reviewed: Aristotle's
factors of scientific explanation drawn from
Introduction: The his Physics and his Metaphysics.

Aristotelian A. A complete explanation, according to Aristotle,

for some feature of natural phenomenon must

Background include the following factors, reasons, or

“causes.” What's responsible or the aitia (αἰτία)
is often translated as “causes”; hence the title
Abstract: Thomas's “Five Ways” (Quinque reference used in many sources citing these
factors is “Aristotle's Doctrine of the Four
Viae from the Summa Theologiae) or five
Causes.” In point of fact, Aristotle's four factors
proofs for the existence of God are answer why-questions about how natural
summarized together with some standard processes “come about.” Note that modern
objections. The arguments are often named science only began to progress many centuries
as follows: (1) argument from motion, (2) later when most of Aristotle's factors of
argument from efficient cause, (3) argument explanation, which proved to be too rigorous for
from necessary being, (4) argument from much (scientific) discovery, were dropped in
gradations of goodness, and (5) argument favor of the efficient factor alone, with
from design. occasional use of the final factor (especially, as
in the biological and social sciences). Francis
Bacon states in Novum Organumthat science
I. Notes for Thomas Aquinas' five arguments was unable to progress on account of Aristotle's
are available in six parts. The first part, on overly rigid restrictions on explanation—
this page, summarizes the background of especially in Aristotle's linking natural
Aristotelian science, and the other five philosophy to logic.
parts are arguments in separate Webpages
accessed with the five links listed below:
1. The material factor: the ultimate
substratum of matter consists of the
A. Aristotelian science (this page): The elements from which all particular things
Aristotelian Background arise. Matter is the possibility of form.
Matter has the potential to form. A baby is
B. Part I. The Argument from Motion. (Thomas the matter of the form of a child; a child is
argues that since everything that moves is the matter of the form of an adult.
moved by another, there must thereby exist
an Unmoved Mover.) 2. The efficient factor: the source of the
movement of particular things accounts for
C. Part II. The Argument from Efficient the generation or the coming to be and the
Cause. (The sequence of causes which make passing away of those particular things.
up this universe must have a First Cause.) The efficient factor is what is ordinarily
meant by the contemporary use of the
D. Part III. The Argument to Necessary term “cause.” Although change is the
Being. (Since all existent things depend upon actualization of potential, actuality
other things for their existence, there must precedes potentiality in that something
exist at least one thing that is not dependent actual “causes” potentiality to reach
and so is a Necessary Being.) another form.

E. Part IV. The Argument from Gradation. (Since 3. The formal factor: the essence or the
all existent things can be compared to such form or pattern of particular things. Form
qualities as degrees of goodness, there must is the actuality of matter—not just the
exist something that is an Absolutely Good shape, but the factor or formation of the
Being.) potential or the capacity of matter. The
ultimate fulfilment of a sequence of forms
F. Part V. The Argument from Design. (Also is the final form or final factor.
named “The Teleological Argument”— The
intricate design and order of existent things 4. The final factor: The purpose of a thing
and natural processes imply that a Great accounts for the end or the good of a thing
Designer exists.) —i.e., what it's for. The development of
 natural processes move to completion— Aristotle's “scientific” characterization of
what a thing is designed to achieve or do. the natural world because it is a
The internal design of things is part of the manufactured object.)
ordinary action of natural factors.
1. The material factor includes steel, wood,
and paint. From this factor alone, we have
not, of course, explained the object.

2. The formal factor is displayed by the

picture in its two-dimensional aspect. The
form may be described as an open cage
set upon a pole. From this factor in
addition to the material factor, we have not
given enough of an account to say that we
have definite knowledge concerning the
object at hand.

3. The efficient factor is how the form came

to be from the material factor or matter.
Here, the cause is provided by wood-
B. As an example of the use of
working tools and metal fashioning tools
Aristotle's four factors of explanation,
together with the energy and forces from
consider the object in the picture to the
such factors as electricity, gasoline, and
right. To explain what this object is, we
human chemical energy sources like
would include all four factors in our
adenosine tri-phosphate. Yet, these three
explication. (The manufactured object in
general factors are still insufficient for
the picture was chosen for brevity of
understanding completely the object under
explanation with the recognition that this
inspection.
object is not in accordance with of

4. Thus, it is only when we come to know the purpose of the particular object that enough becomes
known so as to constitute knowledge of the phenomenon—we come to know the final or teleological
factor: what it's for. The proper function of this object is its use as a fruit-picker.

Part I: Thomas
argument cannot be criticized on the grounds
that the conclusion does not follow with absolute
necessity.
Aquinas, "The B. Also, note that the concept of motion involves
Argument from dependency, not necessarily temporal
succession. In other words, the argument
Motion" from motion relies on the concepts of
potentiality and actuality rather than that of
causal sequence.
Abstract: Thomas' argument that since
everything that moves is moved by another, C. The Argument from Motion:
there must thereby exist an Unmoved Mover
is outlined and explained. Objections to that 1. Evident to our senses in motion—the
argument are also briefly examined. movement from actuality to potentiality.
Things are acted on. (Again, note that the
argument proceeds from empirical
I. Aquinas' Argument from Motion begins evidence; hence it is an à posteriori or an
with the empirical observation of motion in inductive argument.)
the world. Hence, this argument is an à
posteriori argument, and the conclusion is 2. Whatever is moved is moved by something
not claimed to follow with certainty. else. Potentiality is only moved by
actuality. (An actual oak tree is what
A. Thus, if Aquinas' argument is correct, the produces the potentitality of an acorn.)
degree of the truth of the conclusion would be
comparable to the conclusions of the findings of
modern science. It is important to see that since
no claim is made as to the certainty of the
conclusion but only as to its probability, the
 3. Unless there is a First Mover, there can be C. By the principle of simplicity, isn't more
no motions. To take away the actual is to reasonable to suppose that the universe of
take away the potential. (Hence, which objects in motion has always existed than to
came first for Aristotle, the chicken or the suppose that we have to account for how
egg?) things came from nothing? Such a
supposition would be in accordance with
a. (E.g., the reason a student has the Newton's first law of motion, the so-called law
potential to be awake is that he had of inertia:
(actual) toast for breakfast. Toast has the  An object at rest tends to stay at rest and an
potential to keep the student awake. But object in motion tends to stay in motion with the
(actual) bread has the potential to become same speed and in the same direction unless acted
toast, and actual grain has the potential to upon by an outside force.
become bread. Actual water, dirt, and air Therefore, neither movement nor rest is
have the potential to become grain. To necessarily the default state of the universe.
take away any of these actualities is Hence, the Big Bang theory of the origin of
ultimately to take away the potential for the universe and the Big Rip Theory are
the student to be alert.) Thomas Aquinas, "The
initially
Argument from Efficient Cause"
b. (Aquinas is not rejecting an indefinite or
an infinite series as such, the idea is
that a lower element depends on a Abstract: Thomas' First Cause Argument for
higher element as in a hierarchy, not a the existence of God is outlined and briefly
temporal series.) clarified. Some standard objections to that
argument are listed.
4. Thus, a First Mover exists.
I. Thomas' Argument from Efficient Cause
II. Summary list of common objections to the begins with the empirical observation of
Argument from Motion: causal sequence in the world. Hence, this
argument is an à posteriori argument, and
A. There seems to be a contradiction in the the conclusion is not claimed to follow with
argument. Premise (2), "Whatever is moved is certainty.
moved by another," conflicts with the notion of
God in this argument as that of something A. The Argument from Efficient Cause:
unmoved, i.e., that of the Unmoved Mover. God,
then, is an the exception to the truth of premise 1. There is an efficient cause for everything;
(2). Nevertheless, cannot God move or act? If nothing can be the efficient cause of itself.
God is pure actuality, then it would seem to
follow that God can't do anything, for God is
2. It is not possible to regress to infinity in
already all that God could be. If, then, God is
efficient causes.
already all that God can be, there's no potential
for God to be able to act or be in any way
3. To take away the cause is to take away the
different from what God is. If God is claimed to
effect.
have a privileged status and not subject to the
firse premise, then the argument becomes
viciously circular. 4. If there be no first cause then there will be
no others.
B. There are inherent problems with the
concepts of actuality and potentiality. Why 5. Therefore, a First Cause exists (and this is
must we presuppose natural processes have a God).
beginning, middle, and end? Is such a
scheme a natual one, or is this paradigm B. The nature of causality is a difficult field of
imposed by the nature of our thought? Why study. Centuries after Thomas, David
must there be a beginning to the universe? Hume raises serious objections to cogency
of the concept of causality. Examples
illustrating a few of difficulties of the
concept of causality which are missed by
Thomas' notion of the efficient cause of
factor are as follows:

1. Problem of Accidental Correlation. How

can a distinction be maintained between a
universal accidental correlation and a
 necessary connection? Simply because of the universe (to use David Hume's
substances or events of the kind B always phrase) is not just a linear sequence. If the
follow substances or events of the sequence of causes were infinite, there
kind A does not imply that A caused B. Cf., would be no cause which was " taken
the variety of the informal fallacy of False away."
Cause called post hoc ergo propter hoc. It
is conceivable that such a sequence of a. Causality can be seen as a web of
generally occurring states of affairs is interrelated events whereby each event is
attributable to an improbable accidental or connected to each and every other event
chance series of occurrences or is directly or remotely. (Any loose end or
attributable to factors other than causality. non-connected event would count as an
event not subject to the laws of nature and
2. Problem of Simultaneous Causation If so would be a miracle.)
actual causal relations are examined
closely, any supposed causal connection b. To list all of the conditions for the
would be seen to be instantaneous. occurrence of an event would be to
include a description of the state of the
a. Immanuel Kant cites these examples: universe down to the location and
 If I view as a cause a ball which impresses a momentuum of each and every
hollow as it lies on a stuffed cushion, the elementary bit of physical substance.
cause is simultaneous with the
effect. Critique of Pure Reason (A203=B248) c. There might be different lines of webs of
… A glass [filled with water] is the cause of causality leadings to multiple first
the rising of the water above its horizontal causes.
surface, although both appearances are
simultaneous. Critique of Pure 4. Finally, of course, there is no proof that a
Reason (A204=B249). First Cause is the same entity as the
beings noted in the conclusion of the other
b. Note that if the coupling of the cars of a train Five Ways.
to the locomotive are rigid and the parts of
the train are not elastic, as soon as the II. Summary list of common objections to
engine moves, the caboose moves. There Thomas' Argument from Cause:
would be no gap in time.
A. There seems to be a contradiction in the
c. We say the vibration of a string on a argument. The first premise states, "There is an
musical instrument causes a sound, but efficient cause for everything, nothing can be
the string does not vibrate first followed the efficient cause of itself." Is, then, God
later by the sound. something or nothing? If God is something, then
we can ask the question of children, "What
d. Consider the striking of a match causes caused God?" If God is nothing, then God's
the match to light. If we look closely, existence is not proven. If God is claimed to
there are actually an indefinite number have a privileged status, then the argument
of sequences of causes as friction of the becomes viciously circular.
striking causes the rapid vibration of red
phosphorus atoms which in turn are B. Thomas oversimplifies the nature of causality
transferred individually to the sulphur in terms of a temporal sequence of causes.
compounds and then individually to the Contemporary physics (as the best
molecules of wood. The sequential epistemological result to date) has many
agitation of chemicals may be analyzed different notions of relations of events—
as moving at the speed of light among including no causality (only correlations
an indefinite number of points of ignition between events), simultaneous causation,
—which, from an Einsteinian point of backward causation, causation at a distance
view, can be seen as instantaneous. (cf., Bell's Theorem or quantum
entanglement), or merely mathematical
e. Finally, consider how old the universe description.
would be if causes are simultaneous
with their effects. Time would seem to C. By Occam's Razor, (the principle of simplicity
be an illusion. or the principle of parsimony), we cannot
assume that time has a beginning, middle,
3. Problem of Uncaused Events. Consider and end as assumed by Thomas' argument on
Thomas' sequence of causes. The cement the historical basis of Aristotle's description
 of plot in his Poetics,. If we assume that the Necessary Being, Greatest Good, or Great
universe was always existent, we do not have Designer. A separate argument would be
to account for a beginning. The early Greek necessary to show that all these "gods" are
philosophers, for example, did not assume the same God.
there was a beginning of time.As Isaac
Newton points out in his "Rules for Reasoning H. Fallacy of Composition. Simply because
in Philosophy": causality occurs within the universe, it does
 Rule I. We are to admit no more causes of natural not logically follow there must be a grand
things than such as are both true and sufficient to cause for the exisence of all of the separate
explain their appearances. To this purpose the causes in the whole universe. Moreover,
philosophers say that Nature does nothing in vain, Thomas' assertion that "To take away the
and more is in vain when less will serve; for Nature cause is to take away the effect" would not
is pleased with simplicity, and affects not the pomp hold for an infinite regress of causes since
of superfluous causes. there is no cause taken away

D. By the principle of simplicity, it is D. less plausible than the Steady State

arguable that an infinite regress in Theory, the Loop or Cyclical Theory or
causes is more reasonable than the the Pulsating Universe theory.
notion of an infinite, all powerful
God who created a world with non- E. Natural processes might be best explained without
moral evil (i.e., "acts of God" such recourse to the dependence of one part to others.
Can the notion of the independent interdependence
as flood, hurricane, earthquake, or
of parts of the universe be just as plausible a
plague). If God is perfect as a notion as some sort of sequence of relations
cause, so must be the effects of whereby we have to account for the sudden
that cause. And, as well, since existence of the beginning? For example,
causes are proportioned to the if Einstein's Theory of Relativity is correct, absolute
effect, the Deity must be as finite motion with reference to three-dimensional space
as the universe is finite. Again, as would be replaced with the idea that there is no
Isaac Newton points out in his absolute frame of reference since the motion of
anything can only be measured by comparing it
"Rules for Reasoning in
relatively with the motion of something else—
Philosophy": gravity, acceleration, and motion affect the
 Rule II. Therefore to the same natural effects we measurment of time and space.
must, as far as possible, assign the same causes. “The first mover, in [the argument from motion] is
As to respiration in a man and in a beast; the not temporally prior to the movers that depend on
descent of stones [meteorites) in Europe and in it. It is above them all and exists simultaneously
America; the light of our culinary fire and of the
with them all, somewhat the way that the sun is
sun; the reflection of light in the earth, and in the
the cause of the growth of plants that have
planets.
secondary causes that produce them successively
season after season. The first or prime mover is
E. If the first premise "There is an
efficient cause for everything; not of the same order as the things it moves, nor
nothing can be the efficient cause does it move thing in the same way as the
of itself" is true, then the secondary causes do.” Stephen F. Brown, “Thomas
occurrence of miracles is ruled out. Aquinas,” The Columbia History of Western
A miracle is a violation of a law of Philosophy, ed. Richard H. Popkin and Stephen F.
nature. Ruling out miracles is not Brown (Columbia University Press, 2005)
something Thomas would want to
do.
25

F. One can envision many possibilities. Even if

there were a first cause, it would not
necessarily follow that this first cause was
God any more than the second cause in the
sequence is God. It could be that there are
many gods as first causes. It could be that
the universe of causes circle back on itself so
that there is no first cause, but every effect
has a cause.

G. Also, it does not follow that the first cause

would be the same entity as the conclusion of
the other arguments: Unmoved Mover,