Chapter
3:
Knowing
That God Exists (1a,1,2)
Summa
Theologiae 1a,2 is titled de Deo, an Deus sit (“Does God exist?”). Consisting
of only three much-quoted articles, it gives us the start of the Sum ma’s
treatment of natural theology.1
Aquinas believes that before embarking on a “scientific” study of anything we
need to know that the thing in question exists, and this is the thought that
governs what he says in 1a,2. Aquinas distinguishes between the questions an
est (“Does it exist?”) and quid est (“What is it?”), and he will turn to the
question “What is God?” in 1a,3. In 1a,2, however, his focus is on what we
might call “the mere existence” of God. Does this mean that 1a,2 is offered by
Aquinas as a help to people with no belief in God? Not quite, given 1a,1. Even
in 1a,2, Aquinas is writing for Christians. Yet Aquinas does think that a good
philosophical case can be made in defense of the truth of the proposition “God
exists,” and in 1a,2 he aims to indicate what that case amounts to.
3.1
Per se Notum (1a,2,1)
Aquinas’s
position is that we can only know that God exists by means of causal inference
from God’s effects.2 He is, however,
aware that some people have taken “God exists” (Deus est) to be known to be
true without reference to causal reasoning. He discusses this way of thinking
in 1a,2,1, where he raises the question “Is it self-evident (per se notum) that
God exists?”
Per
se notum literally means “known through itself,” and Aquinas takes the claim
that “God exists” is per se notum to hold that the truth of “God exists” is
something we can arrive at by virtue of some understanding we have of God not
grounded in causal reasoning—that “God exists” is known by us in some basic way
just because we are thinking things that we are.3
More specifically, in 1a,2,1 he takes it to amount to three arguments: (1)
Knowledge of God is implanted in us by nature; (2) Once we understand what the
word “God” means, we can see that it would be self-contradictory to deny that
God exists; (3) Since God is Truth, and since we cannot consistently assert
that it is true that there is no truth, God evidently exists. Aquinas is partly
sympathetic to these arguments. He agrees, for example, that everyone has a
desire for God since everyone naturally desires happiness and since our
ultimate happiness is to be found only in God. He also agrees that if we could
understand what God is we would immediately see that God cannot but exist. And
he accepts that there evidently is such a thing as truth. At the same time,
however, he rejects (1) to (3) just noted. Vaguely to desire God is not, he
says, to know that God exists any more than to recognize that someone is coming
is to know who exactly it is that is coming. And there being truth in general
does not imply that there is anything to be dignified by the title “First
Truth” (i.e., God).
Argument
(2) is today, perhaps, the best known version of what Aquinas has in mind when
thinking of the claim that Deus est is per se notum. That is because, as
Aquinas presents it in 1a,2,1, it reads like a famous argument (usually
referred to as the “Ontological Argument”) first presented by St. Anselm of
Canterbury (1033–1109) in his Proslogion.4
This argument is de fended by some philosophers today, so there is a lot of
contemporary literature on it.5 As
Aquinas presents the argument (without citing Anselm as its source), it runs:
“Once we understand the meaning of the word ‘God,’ we immediately see that God
exists. For the word means ‘that than which nothing greater can be signified.’
So, since what exists in thought and fact is greater than what exists in
thought alone, and since, once we understand the word ‘God,’ God exists in
thought, God must also exist in fact.”6
Anselm
says more than this in defense of his ontological argument, but Aquinas seems
unconcerned with the details of Anselm’s argument or with Anselm’s defense of
himself to one of his contemporaries.7
Rather, he focuses on the general idea that we have an understanding of God
that leaves us being inconsistent should we go on to deny that God exists. He
writes:
Even
if someone thinks that what is signified by ‘God’ is ‘that than which nothing
greater can be thought’, it does not follow that the person in question thinks
that what is signified by ‘God’ exists in reality rather than merely as thought
about. If we do not grant that something in fact exists than which nothing
greater can be thought (and nobody denying the existence of God would grant
this), the conclusion that God in fact exists does not follow.
Critics
of versions of the Ontological Argument have often suggested that we cannot
conclude from the meaning of the word “God” that there is anything in reality
corresponding to it, and Aquinas seems to support this line of thinking, though
he does agree that a knowledge of what God actually is would leave us with an
understanding that God has to be. In 1a,3, he will argue that it is God’s
nature to exist. So Aquinas does think that God cannot but exist. In 1a,2,1,
however, he is criticizing approaches defending the truth of Deus est, which
seem to presume a knowledge concerning God that, in Aquinas’s view, we lack. He
makes a distinction between what is per se notum in itself (per se) and what is
per se notum to us (quoad nos). He thinks that Deus est is “self evident in
itself” in that it is God’s nature to exist. But, as we shall soon see, he
denies that we have a God’s-eye view of what God is.
3.2
Demonstrating That God Exists (1a,2,2–3)
Some
philosophers have said that we come to know that God exists by employing what
they call “intuition.” The idea here is that, with no reliance on inferential
argument, we know that God exists by just seeing all at once that this is so.8 Such is not Aquinas’s view, however, and in
1a,2,2 and 3 he maintains that we can demonstrate that God exists. Yet what
does Aquinas mean by “demonstrate” and “demonstration”? He takes a
demonstration to be an argument that, starting with true premises, entails its
conclusion formally or validly. Here Aquinas is drawing on Aristotle’s
Posterior Analytics.
He
takes a demonstrative argument to have the form: (1) “All X is Y” (e.g., “All
human beings are mammals”); (2) “All Y is Z” (e.g., “All mammals breathe air”);
(3) “Therefore, All X is Z” (e.g., “Therefore, all human beings breathe air”).
Given (1) and (2), (3) follows necessarily. This is not to say, as some would,
that (1) to (3) erroneously “beg the question” since (3) seems to be somehow
“contained” in (1) and (2). All valid deductive arguments beg the question
inasmuch as all of their conclusions are implied by their premises.9 But a good demonstrative argument, as Aquinas
understands it, still leads us from known truth to yet more truth. So he thinks
of it as an especially forceful kind of argument, and he holds that such
argument is avail able to those who conclude that God exists.
As
I noted in chapter 2, some theologians have resisted this conclusion of
Aquinas, a prominent example being Karl Barth. And some of their objections to
it seem to be anticipated by Aquinas in 1a,2,2.10
How,
one might ask, can it be demonstrated that God exists since it is an article of
faith that this is so? And is it not absurd to seek to demonstrate that God
exists given that God and creatures are incommensurable (God being infinite and
creatures being finite)? Also, what about the (1)–(3) pattern of argument that
I have just noted? Does it not seem to rely on an understanding of what Y
stands for (mammals in my examples)? Yet should we not accept that we do not
know what God is? If we cannot know what God is, however, how can we proceed to
a demonstration that God exists? In 1a,2,2, Aquinas raises all of these
questions while proceeding to argue that there is nothing wrong in principle
with the idea that it is possible to demonstrate that God exists.11
In
doing so, he denies that “God exists” is an article of faith (1a,2,2 ad.1).
Here he is thinking in terms of the Nicene Creed, and his point is that the
creed presupposes that God exists and does not explicitly proclaim that this is
so. Readers of 1a,2,2 will perhaps grasp what Aquinas is saying about “God
exists” not being an article of faith by noting what he observes in 2a2ae,1,8.
There he says that the articles of faith are properly formulated and that the
first article of faith is that there is but one God—not that it is true to say
that God exists. By contrast to what some philosophers have argued, Aquinas in
1a,2,2 asserts that there is “nothing to stop people from accepting on faith
some demonstrable truth that they cannot personally demonstrate.”12 He does not, however, take this thought to
imply that there cannot be a demonstration of the claim that God exists.
In
true Barthian fashion, Aquinas agrees that God and creatures are seriously different
from each other. He suggests, however, that we need to distinguish between a
comprehensive knowledge of God and some knowledge of God. We can know that God
exists even if we lack a comprehensive knowledge of what God is (1a,2,2, ad.3).
Here Aquinas is saying that a demonstration of the truth of “God exists” does
not have to be thought of as including an understanding of what God is. Yet how
does Aquinas take himself to be able to argue that it can be demonstrated that
God exists, given that we do not know what God is, while providing an argument
of the kind (1)–(3) noted above?
Anticipating
this question, Aquinas distinguishes between demonstration propter quid
(literally, “on account of the whatness”) and demonstration quia (“that”). He
says (1a,2,2): “There are two kinds of demonstration. One kind, propter quid,
argues from cause to effect and proceeds by means of what is unqualifiedly
first. The other, demonstration quia, argues from effect to cause and proceeds
by means of what is first so far as we are concerned.”13 Here Aquinas is thinking of a propter quid
demonstration as an argument that proceeds from an understanding of what
something is.
Consider
the following argument: (1) Cats are mammals; (2) Smokey is a cat; (3)
therefore, Smokey is a mammal. We get to (3) here, Aquinas thinks, on the basis
of an understanding of what cats actually are and on the basis of knowing what
some particular cat (Smokey) is. Given that we know that cats are mammals, and
given that we know that Smokey is a cat, we can readily conclude that Smokey is
a mammal.
But
now consider this scenario: We try to push a door open but encounter
resistance. We shall presumably conclude that something accounts for the door
not opening, but we might not know what the something in question is.
Nevertheless, we might do our best to say something about the cause of the door
not opening based on our knowledge that the door is meeting resistance. Here we
might argue along these lines: “Well, something is blocking the door.” And we might
then speculate about what the thing in question is based on what we are
observing. Here, Aquinas is thinking, we would be engaging in a demonstration
quia. We would be arguing from an effect we know well to a cause that we do not
know as well. Aquinas thinks that such a demonstration quia might be possible
when it comes to arguing philosophically for the truth of “God exists” even
though we do not know what God is (something on which he will say more in
1a,1,3).
Note,
however, that in taking this line Aquinas holds that we need some initial
understanding of the word “God.” I might not know what X actually is; I might
not, as Aquinas would say, know what its essence is. But in arguing that X is
the cause or explanations of something I am familiar with, I have to work with
some nominal definition of X. By “nominal definition” I mean an explanation of
what a word means as opposed to an account of what some actually existing thing
is by nature. There may be no wizards, but I can explain what the word “wizard”
means (as dictionaries do). Thus, for example, suppose I argue that E, which I
take to be an effect, is to be accounted for in terms of C, which I take to be
the cause of the effect. Suppose, for instance, I argue that a human being with
abilities X, Y, and Z accounts for there being a human corpse before me. To
prove this I shall have to proceed by working the understanding of C as “human
being with abilities X, Y, and Z” into my argument. Accepting this point,
Aquinas, in 1a,2,3 goes on to argue for the truth of “God exists” by employing
a series of nominal definitions of the word “God” and by using them in a set of
causal arguments.
3.3
Arguing for God Causally (1a,2,3)
Aquinas
uses the Latin word causa to mean more than we typically signify by “cause.”14 When we are asking what caused what, we are,
so to speak, normally looking for a culprit. Hence, for example, a doctor might
wonder what virus is causing the symptoms of a patient. However, and as is
indicated by our use of the word “because,” causes might not just be things in
the world (like viruses) that act so as to bring about changes in other things
(such as healthy human beings). Also, they might not be things in the world
that bring about the persist ence of some state of affairs. For example, a
crystal glass that I drop might shatter because it is made of crystal as
opposed to plastic. My cat might meow because of what it is by nature, and I
might be racing to the railway station because I need to catch a particular
train. Aquinas has these uses of “cause” or “because” in mind when he
distinguishes in 1a,2,2 between demonstrations propter quid and demonstrations
quia. In moving to 1a,2,3, however, he is concerned with what I am calling the
“culprit” sense of cause. Suppose that I feel a tap on my shoulder. I will
react and turn around while looking. Here I am reacting to what Aquinas would
have called an “agent cause” or “efficient cause.” I am looking for some
particular thing whose action is the tap I feel on my back. Similarly,
Aquinas’s Summa Theologiae arguments for the truth of “God exists” are all
arguments for the existence of God considered as an agent cause.15
You
may wonder why I have so far spoken of Aquinas as looking to show that “God
exists” is true. Should I not have instead said that Aquinas seeks to prove or
demonstrate the existence of God? The answer is no since, as we shall see,
Aquinas thinks that God’s existence (esse) is not to be distinguished from
God’s essence (essentia), which he thinks we cannot know. Yet Aquinas thinks
that he can show that “God exists” is a true proposition defensible with an eye
on agent causation. This is what 1a,2,3 is chiefly about.
3.4
The Five Ways
1a,2,3
presents what Aquinas calls “five ways in which one can prove that there is a
God.” These arguments are famous and have given rise to a huge amount of
literature both expository and critical.16
I cannot here offer a detailed analysis and discussion of them. I shall,
therefore, (1) make some general expository points concerning the Ways as a whole,
(2) present the text of each Way with brief explanatory notes designed to help
you to understand what Aquinas is arguing in them, and (3) briefly draw
attention to some familiar criticisms of the Ways while offering some comment
on these criticisms.
3.4.1
The Ways as a Whole
As
I have noted, Aquinas turns to the business of arguing that “God exists” is
true with an eye on certain nominal definitions of the word “God.” In the Five
Ways these are: (1) “God” means “an uncaused agent cause of change not itself
changed by anything”; (2) “God” means “an uncaused agent cause not itself
having an agent cause, that is, a first agent cause”; (3) “God” means “a source
of the existence (esse) of all things that can be thought of as necessary
beings”; (4) “God” means “the cause of the existence of things displaying
perfection to any degree”; and (5) “God” means “one who directs things lacking
awareness to their ends.” Presuming that we do not know what God is
essentially, Aquinas uses these nominal definitions in the Five Ways so as to
provide demonstrations quia of the truth of “God exists.”
This
point leads me to stress another directly related to it, one concerning what
Aquinas takes himself to have established in his Five Ways. These have sometimes
been criticized as “arguments for the existence of God” on the ground that they
do not establish that God exists as having all the “attributes” ascribed to God
by those who profess belief in God. As I have noted, however, there is a sense
in which it would be wrong to read Aquinas as taking himself to be making the
existence (esse) of God clear in the Ways, and, as we shall see, Aquinas, in a
serious sense, denies that God has any attributes. Also, though sometimes
wrongly read as such, the Ways are not Aquinas’s last word in the Summa
Theologiae when it comes to what he thinks can be known of God by reason as
opposed to revelation. That is why he follows them up with a series of separate
arguments for conclusions such as “God is perfect,” “God is good,” “God is
eternal,” “God is one,” “God knows,” “God loves,” and “God has power.” Insofar
as the Summa Theologiae can be thought of as offering a defense of “God
exists,” the defense is not over until 1a,26—actually, it is not really over
until the end of 1a,45. The Five Ways are but an attempt to get a certain ball
rolling.
A
third point worth noting when it comes to the Ways is that none of them are
arguing in what we might think of as chronological terms. Theists have
sometimes maintained that we can know that God exists since the universe must
have had a beginning and since we can reason to God as accounting for the
beginning of the universe.17 Yet
Aquinas does not think it possible to demonstrate that the universe had a
beginning (as we shall see when we come to 1a,46), and it would be wrong to
read the Ways as claiming that God must be responsible only for something
arising in the past while not being active in what is happening presently. In
1a,2,3, Aquinas denies that there can be an infinite regress of agent causes,
but his denial here presupposes a distinction that he wants to make between a
series of causes ordered per accidens and a series of causes ordered per se.
For
Aquinas, a causal series per accidens, which he thinks might proceed to infinity,
would be referenced by noting, say, that Abraham begat Isaac who begat Jacob
who begat Joseph. On this scenario, Abraham is certainly causally related to
Joseph by being his great-grandfather. Of course, though, Abraham, being dead
at the time, was doing nothing to bring about the conception of Joseph. In the
Five Ways, however, the causal series with respect to which Aquinas denies the
possibility of an infinite regress is a per se one—a series in which a first
cause’s activity runs through a series of effects all of which depend equally
on there being such a first cause.18
Consider
the flame on the cooktop of a gas stove, which is heating a pot sitting on it,
which, in turn, is heating the water it contains, which, in turn, is heating
some spaghetti placed in it. Here the temperature of the pot and the water and
the spaghetti can all be traced to the action of the flame, and Aquinas would
say that in this case we are dealing with a per se causal series. In the Five
Ways, Aquinas starts by noting certain phenomena the occurrence of which at any
time, he thinks, depends on the activity of God. He agrees that particular
instances of these phenomena might be explicable in terms of things other than
God, things that are like them as displaying what they display. He agrees, for
example, that a moving ball might cause another ball to move, and that the
second ball might cause yet another to move. His point, though, is that there
being such phenomena at all cannot be accounted for in terms of something that
displays what they exactly display as we seek to account for them. He thinks,
for example, that nothing caused to change by something can account for there
being things caused to change by other things.19
Finally,
and given what he goes on to say after 1a,2,3, Aquinas takes the Five Ways to
be arguing for what cannot be part of the scientifically observable world, the
world considered as an object of scientific research. The Ways do not present a
series of scientific hypotheses. Aquinas takes them to be suggesting that
things with which we are familiar ought to lead us to suppose that there is
something that is quite distinct from the world considered as something to be
explored scientifically.
3.4.2
The First Way
It
is certain, and clear to our senses, that some things in the world undergo
change. But anything in process of change is changed by something else. For
nothing can be undergoing change unless it is potentially whatever it ends up
being after its process of change—while something causes change insofar as it
is actual in some way. After all, to change something is simply to bring it
from potentiality to actuality, and this can only be done by something that is
somehow actual: thus fire (actually hot) causes wood (able to be hot) to become
actually hot, and thus it changes and modifies it. But something cannot be
simultaneously actually x and potentially x (something actually hot, for
instance, cannot also be potentially hot, though it can be potentially cold).
So, something in process of change cannot itself cause that same change. It
cannot change itself. Necessarily, therefore, anything in process of change is
changed by something else. And this something else, if in process of change, is
itself changed by yet another thing; and this last by another. But there has to
be an end to this regress of causes, otherwise there will be no first cause of
change, and, as a result, no subsequent causes of change. For it is only when
acted upon by a first cause that intermediate causes produce change (if a hand
does not move the stick, the stick will not move anything else). So, we are
bound to arrive at some first cause of change that is not itself changed by
anything, which is what everybody takes God to be.20
Here
note:
(a)
The second sentence quoted above reads in Aquinas’s Latin Omne autem quod
movetur ab alio movetur, which can also be translated as “Anything changed is
changed by something else.” Because of ambiguity concerning Latin usage when it
comes to the verb movere (“to move”), scholars have asked whether the First Way
is starting from the fact that some things are passively acted on as they
change (are changed) or starting from the fact that things just go through a
process of change (are changing). You might think that “everything changed is
changed by something else” is so obviously true that Aquinas cannot go on to
argue for its truth as he does in the First Way. But, of course, something can
be changed by itself, as when I cut myself. And one might well construe the
First Way as starting from the fact that things are changed (passive) and not
from the fact that things change (intransitive).
(b)
Like each of the Five Ways, the First Way begins with what we might callan
observational premise. This is that some things in the world undergo change
(motus). By motus Aquinas means real change in general.21 The First Way has often been described as an
argument for there being an unmoved mover. “Motion,” however, is commonly taken
these days to refer only to local motion, and we need to realize that Aquinas
takes motus to include not just change of place but also change of quantity, as
when I put on weight, or quality, as when I acquire a suntan.22 The First Way is arguing that instances of
change in these senses depend on something bringing the change about.
(c)
At the center of the First Way’s argument is the claim that motus occurs as
something comes to be what it is not to start with because something that is
actually able to account for this is actually doing so. In making this claim,
Aquinas distinguishes between something being potentially thus and so and
something being actually thus and so. Here he is distinguishing between (1)
something now thus and so though able to be different, and (2) something just
being real (aliquid ens actu—“some real thing”). He would say, for example,
that, though I am actually sitting at a desk I could be standing in my kitchen.
Then he would say that my coming to be standing in my kitchen is brought about
by something real.23 He would also
say that something potentially thus and so coming to be actually thus and so is
not explicable in terms of what the thing is to start with, that X coming to be
F is not explicable with reference to a description of what X is before it
comes to be F. He certainly thinks that a description of X as being F can be a
genuine description of X. But he does not think that it accounts for X coming
to be F having previously been not F. Here he looks for something distinct from
X as not F, and, we should realize, in spite of the heat example he uses in the
First Way, he does not thereby commit himself to the principle that whatever
accounts for X coming to be F must itself be F in the way X is F once it has
come to be F. He does not, for ex ample, think that if I break your arm I must
myself have a broken arm. What he thinks is that if you end up with a broken
arm, that will be because of something (or maybe more than one thing) that
actually exists and has the power to bring it about that your arm is broken.
(d)
In the First Way, Aquinas denies that there can be an infinite regress of
changers. We should remember that the infinite series that he is here denying
is a series ordered per se.
3.4.3
The Second Way
We
find that there is an order of efficient causes in the observable world. Yet we
never observe, nor ever could, something efficiently causing itself. For this
would mean that it preceded itself, which it cannot do. But an order of
efficient causes cannot go back infinitely, for an earlier member in it causes
an intermediate, and the intermediate causes a last (whether the intermediate
be one or many). If you eliminate a cause, however, you also eliminate its
effects. So, there cannot be a last cause, nor an intermediate one, unless
there is a first. If there is no end to the series of efficient causes,
therefore, and if, as a consequence, there is no first cause, there would be no
intermediate efficient causes either, and no last effect, which is clearly not
the case. So we have to posit a first cause, which everyone calls “God.”24
Here
note:
(a)
When talking about efficient causes in the Second Way, Aquinas starts from the
premise that there are agent causes in the world, causes that, just by being
so, have effects. He is alluding to the fact that, for ex ample, we can be
clearly aware that the pages of a book I am reading are being turned over by
me, or that barbers cut people’s hair. Since examples such as these evidently
involve instances of what Aquinas would call motus, the concern of the Second
Way clearly overlaps with what the First Way talks about, though, by contrast
to the First Way, the Second Way proceeds by reference to observable causality
taken itself as an effect to be explained by reference to a further cause, and
not from a non-causal effect to a cause.
(b)
Aquinas takes it to be obvious that there is agent causation in the world. You
should realize, however, that he would not take all such causation to involve
the bringing about of a change in something. You might think that a picture on
a wall stays in position because it is supported by what it is hanging on, and
you may think that what it hangs on stays there because it is supported by the
wall into which it is driven. And Aquinas would think the same. So the Second
Way is not just concerned with causes of change but also with causes of a
status quo obtaining by virtue of something else.
(c)
In the Second Way, Aquinas is arguing for a “first cause,” and it has been
suggested that he is, therefore, arguing that there has to be a cause for the
sheer existence (esse) of anything that exists, as he does in De Ente et
Essentia,4. There he argues (1) that understanding what existing things are by
nature does not come with the understanding that some particular things exist
(that, for example, understanding what cats are does not guar antee that one
understands that my cat or any particular cat exists), and (2) that we need to
account for there being things that do not exist by nature. But Aquinas is not
arguing along these lines in the Second Way, though he is evidently concerned
with things coming to be somehow, if only because he would take it that coming
to be thus and so because of an agent cause is always a matter of something
coming to a way of being or having its way of being maintained. Like all of the
Five Ways, the Second Way begins with an observational premise and is not
concerned, as is the De Ente et Essentia, with maintaining (without critical
reference to an observational premise) that the existence of things other than
God can be distinguished from their natures and that there has to be a cause of
such things existing on pain of an infinite regress of causes. What he claims
in the Second Way is that we observe agent or efficient causes to be ordered to
effects.25 In other words, thinks
Aquinas, there evidently are effects of efficient or agent causes and,
therefore, efficient causes of effects.
(d)
Given the observational nature of the start of the Second Way, and given that
Aquinas takes observable agent or efficient causation to include cases where
change in one thing comes about by virtue of something else, the Second Way can
be read as parallel to the reasoning of the First Way while concentrating
(though not exclusively) on causes of motus rather than on motus considered as
an effect.26
(e)
In the Second Way, Aquinas appears to presume that nothing can be its own
efficient cause without being prior to itself. As John Wippel observes, he
seems to be thinking that “for something to cause itself efficiently, it would
have to exist in order to cause (itself), and yet would not exist, insofar as
it was being caused.”27 The reasoning
here is comparable to or, indeed, exemplified by that of “Nothing can itself
account for the warmth it is getting from something else.” You might, perhaps,
think that something can be or can come to be while lacking what Aquinas thinks
of as an agent or efficient cause. In the Second Way, however, Aquinas is not
arguing otherwise; indeed, he is arguing that something can be while lacking an
agent cause. His point about nothing being its own efficient cause amounts to a
claim concerning what has to be the case only of what is efficiently caused (a
change in something owing to something, or the maintaining of something’s
physical position owing to something, and so on). When it comes to this, he
thinks, another is required.
(f)
In the Second Way, Aquinas denies that there can be an infinite regress of
efficient causes. We should remember, however, that the infinite series that he
is here denying is a series ordered per se.
3.4.4
The Third Way
Some
of the things we encounter are able to be or not to be, for we find them
generated and perished (and, therefore, able to be or not to be). But not
everything can be like this. For something that is capable of not being, at
some time is not. So, if everything is able not to be, at some time there was
nothing in the world. But if that were true, there would be nothing even now,
for something that does not exist is only brought into being by something that
does exist. Therefore, if nothing existed, nothing could have begun to exist,
and nothing would exist now, which is patently not the case. So, not everything
is the sort of thing that is able to be or not to be. There has got to be
something that must be. Yet a thing that must be either does or does not have a
cause of its necessity outside itself. And just as we must stop somewhere in a
series of efficient causes, so we must also stop in the series of things which
must be and owe this to something else. This means that we are forced to posit
something which is intrinsically necessary, owing its necessity to nothing
else, something which is the cause that other things must be.28
Here
note:
(a)
The observational premise in the Third Way is “Some things come to be generated
and some things perish.” Aquinas’s reference to generation and perishing here
seems to imply that he is thinking of examples such as “People come to be as
other people mate” or “People die.”
(b)
The coming to be and passing away to which Aquinas refers in his Third Way
involves what he would call “substantial change.” For him, a substantial change
occurs when a genuine substance ceases to exist because of the activity of
something other than it, as when a cat is put to sleep by a vet.29 Strictly speaking, Aquinas thinks, a
substantial change is not a change undergone by something that exists
throughout the course of the change in question—it is not an “accidental
change.” He recognizes, for instance, that, while my cat exists through the
changes it undergoes when I clip its claws, it does not exist before its
generation and after its demise. Yet he also thinks that some changes in the
world amount to a coming to be and a passing away. There are, he believes, more
changes in the world than what he would call “accidental changes.” When I have
clipped my cat’s claws, it has undergone a change, but it has survived as the
cat that it is. What if I kill it, however? It would seem that a change of some
sort has occurred, but not one of which my cat can tell the tale. And what if
my cat breeds and produces kittens? Again, it would seem that a change of some
sort has occurred, but not a change in the kittens, for this is a change
amounting to their coming to exist. It is with an eye on such examples that
Aquinas quite generally in his writings refers to “substantial change,” which
he takes to occur as genuine substances come into being and pass away in the
context of the material world.
(c)
Some readers of Aquinas have taken his Third Way to argue that God, considered
as the one and only necessary being, has to exist in view of the fact that
contingent things exist. These readers have interpreted the Third Way as
holding:
(1)
some things are contingent things;
(2)
all contingent things require a cause to account for their existence;
(3)
so there has to be a single non-contingent necessary thing accounting for the
existence of all contingent things;
(4)
so God exists.
This
argument seems dubious since each contingent thing might have a cause of its
existence without there being a single cause of the existence of all contingent
things.30 Be that as it may, the
argument I have just noted is not that of the Third Way. Aquinas does not use
the word “contingent” in the Third Way. He focuses on things able to be or not
to be in that they come to be and perish.31
And he clearly accepts that there might be more than one necessary being.
(d)
In the Third Way, Aquinas says, “Something that is capable of not being at some
time is not (quandoque non est). So if everything is able not to be, at some
time there was nothing in the world.” Interpreters of Aquinas have disagreed
about how to understand his reasoning here. Some have taken him to be arguing
that if everything is perishable, then everything would have perished by now.32 Others have read him as claiming that if
everything is a generated thing, there would be nothing now since a series of
generated things has to be accounted for with respect to what is not itself
generated. The first reading here seems dubious for two reasons. First, it
leaves us supposing that Aquinas is fallaciously arguing that if everything is
perishable, there has to be a single time at which everything has
perished—while we might reasonably suppose that the fallacy involved here would
have been obvious to someone of Aquinas’s intellectual stature.33 Second, the reading appears to attribute to
Aquinas the view that things able to be or not to be have existed from an
infinite past time, while Aquinas does not articulate this view in the Third
Way, and we know that he did not think it possible to establish philosophically
that the world has existed for an infinite past time.34 So it seems more likely that in the Third Way
Aquinas is focusing on generation rather than perishing and arguing (a) that
things that are generated come to be having not existed before they came to be,
and (b) that if everything is a generated thing, there would be nothing now. On
this reading Aquinas would be saying that anything generated depends on a cause
of its coming to be and that there could not be any generated things unless
there were something acting causally while not itself being something
generated. In support of this reading we might note that in the Third Way, and
as part of his argument to the effect that not everything is able to be or not
to be, Aquinas insists that “something that does not exist is only brought into
being by something that does exist.”
(e)
Unlike some philosophical texts, the Third Way, as I have already noted, is not
arguing that God exists as the only necessary being there is. Having maintained
that not everything is able to be or not to be, Aquinas turns to things not
able to be or not to be (things that are, in his terminology, necessary) while
clearly presuming that there might be more than one of them. And, apart from
what he says in the Third Way, we know that Aquinas believed that there were
many necessary beings, that is, beings not generated or perishable in the
course of nature—such as angels and human souls. So Aquinas does not take
himself in the Third Way to have arrived at the conclusion that God exists
merely by establishing that not everything is able to be or not to be. And he
goes on in the Way to ask whether a series of things not able to be or not to
be can exist without there being something both notable to be or not to be and
existing uncaused. He argues that a series of things not able to be or not to
be has to depend on something that exists uncaused. As he puts it: “Just as we
must stop somewhere in a series of efficient causes, so we must also stop in
the series of things which must be and owe this to something else.”35
3.4.5
The Fourth Way
We
find some things to be more or less good, more or less true, more or less
noble, and so on. But we speak of various things as being more or less F in so far
as they approximate in various ways to what is most F. For example, things are
hotter and hotter the closer they approach to what is hottest. So, something is
the truest and best and most noble of things, and hence the most fully in being.
For, as Aristotle says, the truest things are the things most fully in being.
But when many things possess some property in common, the one most fully
possessing it causes it in the others. To use Aristotle’s ex ample, fire, the
hottest of all things, causes all other things to be hot. So, there is
something that causes in all other things their being, their goodness, and
whatever other perfection they have, and we call this “God.”36
Here
note:
(a)
The observational premise of the Fourth Way might strike some readers as not
being any such thing. For do we observe that some things are more or less good,
true, noble, and so on? In the Fourth Way, Aquinas seems to begin with a
premise with an evaluative component built into it. Some people, though, have wanted
to distinguish sharply between facts and values so as to suggest that none of
our descriptions of observable things in the world entail that these things
should be evaluated in some particular way. They have suggested, for example,
that, from what we know of John by watching him, we cannot conclude that he is
a good man. Aquinas, however, never employs such a fact-value distinction. When
speaking of things in the world he always takes them to be gradable (in
principle, anyway, and albeit with qualifications) with an eye on what we can
see them to be empirically. He would say, for example, that a good cat is not
just well behaved (by some standards of being well behaved that we might have),
but objectively healthy.37 And
Aquinas thinks of health as something detectable by our senses. So he takes the
first premise of his Fourth Way to be an observational one. He regards it as,
for example, truly asserting that we can literally see that some things display
more goodness than other things.
(b)
To understand the Fourth Way one needs to realize that Aquinas regularly takes
being, truth, and goodness to be related in a serious way.38 For him, something that has being is always
to some extent good. He also thinks that things that exist and are, therefore,
good in some way can be thought of as true in that they possess what our minds
can latch onto as intelligible. With these thoughts in mind, Aquinas can say,
as he does in the Fourth Way, that things are good and true. We would not
naturally assert that a cat, say, is true, though we readily refer to true
propositions or statements. But taking truth to amount to a “conformity” of
thing and intellect, Aquinas has no problem in supposing that we grasp truth as
we latch on to what is. And he would have no problem in supposing that to latch
onto the truth about some cat (or whatever) is to be presented not just by a
true proposition or statement but by something that exists and can, therefore,
be said to be true (and good).39
Aquinas will also say that something can be better (more good) than something
else, more true than something else, and more in being than something else. For
Aquinas, something is good insofar as it exhibits actual perfections in some
way— this amounting to it having being to a certain extent—and with this
thought in mind he will say that if X is better than Y, then there is more
present (more being) in X than in Y. Since he holds that truth and being can be
thought of as seriously coinciding, Aquinas will assert that something can be
more true than another thing insofar as it possesses more than another thing
does and is, in this sense, better than it. In the Fourth Way, Aquinas is
drawing on all of these notions, odd or obvious as you might take them to be.
(c)
The Fourth Way starts from the claim that things in the world display different
degrees of perfection. Given what I have just noted, we should not take it just
to be noting that we can grade things within a certain class. We obviously do
exactly this. We say, for example, that cat 1 is healthier than cat 2 and that
cat 3 is healthier than cats 1 and 2. As the ex ample of heat that he gives
indicates, Aquinas is allowing for this kind of comparative evaluation in the
Fourth Way. But the Fourth Way is also working with the thought that comparisons
when it comes to perfections can be made with respect to things of different
kinds. In particular, it is assuming that goodness, which can be had in
different degrees by things of one kind, can be had to a greater degree by
something not belonging to that kind. Since Aquinas thinks that something is
good insofar as it possesses reality, insofar as it exists as it does, he
thinks that where we have more that is real we have more goodness. He does not
take “good” to signify a distinct property as, for example, does “plastic” in
“plastic bag.” Nor does he take “exists” (“has being”) to signify such a
property. But he does think that being good involves being or being actual. So
he holds that even though two things, an angel and a mouse, for instance, might
not belong to one kind, they can be comparatively graded when it comes to
perfection. Aquinas would say that there is more (being) in angels than in
mice. He would therefore say that angels are more perfect than (better than,
more good than) mice. This means that the Fourth Way should not be construed
as, for example, arguing that if some cat is good, and if another cat is better
than it, there has to be a cat that is the best cat of all.
(d)
Like all the Five Ways, the Fourth Way presents a causal argument for the
existence of God as an agent or efficient cause, and its crucial causal move
comes in the words “When many things possess some property in common, the one
most fully possessing it causes it in the others.” What does Aquinas mean when
saying this? He does not mean that, for example, if A, B, and C are green, then
they are all caused to be green by something that is supremely green. He means
that if different things can be thought of as being thus and so, their being
thus and so has to be accounted for in terms of something that has in it the
wherewithal to bring it about that they are thus and so, something whose nature
is reflected in what it brings about. As we can see from texts like his De
Principiis Naturae, Aquinas holds that the effects of agent causes resemble
their causes, but he does not think that they have to look like their causes.
Rather, he maintains, agent causes account for what they produce by being what
they are and, accordingly, explaining the coming to be of what they account
for. I might ask “Why did my cat get sick?” Research might show that my cat
licked up some disinfectant that I spilled on my kitchen floor. Given this
scenario we would say “Well, of course, given that the cat consumed
disinfectant, it is only to be expected that it would get sick.” But why would
we say this? I presume that we would do so because of our knowledge of
disinfectant and the changes it brings about in different things, and Aquinas
would agree with us. He would, however, add that our knowledge of disinfectant
would here have to amount to a knowledge of what it essentially is and not just
a recognition that disinfectant has often produced thus and such effects in
things. To note that cats who drink disinfectant regularly become sick does not
explain why any cat becomes sick having drunk disinfectant. It merely reports
what we have become used to experiencing, and Aquinas would say that
understanding why an agent cause has the effect it does depends on
understanding the nature of the cause (not to mention the things on which it is
acting). Only when one has developed this kind of understanding, thinks
Aquinas, does one know why certain effects show their causes in action and why
the effects in question are only to be expected. When saying that effects
resemble their agent causes and vice versa, he means that agent causes are
somehow reflected in their effects. Aquinas thinks that agent causes sometimes
produce what looks just like them, and in the Fourth Way he gives the example
of fire being hot as things affected by it are hot. But he does not think that
this is always the case, as you need to recognize when reading the Fourth Way.
(e)
As I have noted, the Fourth Way starts with reference to degrees of goodness or
perfection, and it concludes by saying that goodness and being in things we
encounter require a cause. The goodness and being of things in the world,
Aquinas thinks, have to be efficiently caused by something the goodness and
existence of which are not derived from any agent cause. Given the way in which
he thinks that to be good is to be somehow, what this means is that, in the
Fourth Way, Aquinas is effectively asking “How come something rather than
nothing?” while maintaining that there is an answer to this question, albeit
one that we cannot understand. As we shall see, this thought dominates the
reasoning given in the Prima Pars.
3.4.6
The Fifth Way
The
Fifth Way is based on the guidedness of things. For we see that some things
that lack intelligence (i.e., material objects in nature) act for the sake of
an end. This is clear from the fact that they always, or usually, act in the
same way so as to achieve what is best (and therefore tend to a goal and do not
reach it by chance). But things lacking intelligence tend to a goal only as
directed by one with knowledge and understanding. Arrows, for instance, need
archers. So, there is a being with intelligence who directs all natural things
to ends, and we call this being “God.”40
Here
note:
(a)
Some people have argued that the world contains designed objects that demand
explanation with reference to a celestial designer not itself part of the
world. An especially famous example of someone thinking along these lines is
William Paley (1743–1805). In Natural Theology, he compares various naturally
occurring things to watches while arguing that they are made up of parts that
seem put together to achieve a definite result. “Every indication of
contrivance” and “every manifestation of design” that can be found in a watch,
he says, “exists in the works of nature; with the difference, on the side of
nature, of being greater and more.”41
Though some readers of it seem to have thought otherwise, however, the Fifth
Way is not an “argument from design” in Paley’s sense. It does not appeal to
vast cosmic evidence of design not produced by any human being while produced
by a nonhuman designer. Nor is it saying that the world is a single, huge
designed object. Rather, it is noting that some, and only some, things in the
world “act for the sake of an end.” Aquinas is saying that, forgetting about
anything we might know about human behavior, there are some things in the world
that can be thought of as goal-directed in their activity, and his argument is
that the goal-directed activity of these things has to be due to a directing
(nonhuman) intelligence of some kind.
(b)
Why does Aquinas say that certain things “act for the sake of an end”? The
answer to this question can be found in his claim that some things that lack
intelligence “always, or usually, act in the same way so as to achieve what is
best” without doing so “by chance.” Aquinas believes that chance events occur
since (as he says in 1a,116 and 2a2ae,95,5) an event might have no single cause
accounting for just that event. My happening to be killed by the branch of a
tree that falls on me as a gust of wind strikes it just as I pass under it
would, for Aquinas, be an instance of a chance event. But what about the fact
that female cats regularly and instinctively suckle their newborn kittens and
thereby help them to become healthy cats? Or what about the fact that my heart
regularly functions so as to circulate my blood and, accordingly, keep me
alive? These are the kinds of examples that Aquinas seems to be thinking of in
the Fifth Way. In instances like these, he perceives goal-directed activity,
but not activity that is goal-directed because a human being is at work.
(c)
When we seek to account for what we encounter, thinks Aquinas (and if we read
him as though he were speaking English), we are always looking for an account
that begins with the word “because,” as in “This can be accounted for because
of that.” In other words, we are looking for causes most of us these days would
mean when referring to a cause. I presume that when we look for causes we are
normally looking for what Aquinas calls an “agent” or “efficient” cause (as in
“Who killed Fred?”). Following Aristotle, however, Aquinas says that there are
four kinds of cause: efficient, material, formal, and final, and its final
causality that is the focus of the Fifth Way. Although it concludes with
reference to God as an agent cause, the Fifth Way is also much concerned with
final causation in that it begins with the claim that there is goal-directed
activity even on the part of things different from John in that they are not
reasoning or thinking individuals. Such things, Aquinas holds, have
goal-directed tendencies, albeit ones that are sometimes frustrated. In this
sense, he thinks, there are non reasoning things that aim at certain goods,
and, he maintains, such aiming is derivative from what has knowledge or
understanding. Hence, the ex ample he uses of an arrow shot by an archer.
3.5
Critical Responses to the Five Ways
How
cogent is Aquinas’s reasoning in the Five Ways? I cannot note all that has been
said in criticism of them (of which there is a lot), but here are some
arguments that have often been leveled against them:
(a)
The arguments fail because they do not succeed in showing that God exists. At
best, they only show that there is an unchanged changer, an uncaused agent
cause, a necessary being not caused to exist by anything, a source of there
being things with degrees of perfection, and a cause accounting for things in
nature acting for ends. But arguments purporting to show that God exists must
establish that God is, for ex ample, one, omnipotent, omniscient, and any
number of other things. Since the Five Ways do not do this, they fail as
arguments for the conclusion that God exists.
(b)
All of the Ways rest on dubious claims. The First Way, for instance, asks us to
believe that anything undergoing change so as to become F is being changed by
something else that is F. But this principle is obviously false since, for
example, one does not need to be dead to commit murder. Again (so it has been
argued), the First Way was in effect refuted by Isaac Newton (1642–1727) whose
first law of motion states that, because of the principle of inertia, an object
will just continue to move in a straight line in absolute space unless
interfered with.
(c)
We have no good reason to think that any causal series has to have something
uncaused at the start of it.
(d)
All of the Five Ways depend on a logical fallacy that can be illustrated by the
example “All roads lead somewhere; so there is some (one) place to which all
roads lead”—a fallacy sometimes referred to as “the quantifier shift fallacy.”
For instance, the First Way fallaciously argues that since each instance of
motus has an agent cause, there is one agent cause accounting for each instance
of motus. And the Second Way argues in a comparable way with an eye on agent
causality, while the Third Way fallaciously maintains that, since everything
perishes at some time, there must be a time at which everything has perished.
With respect to the Fourth and Fifth Way, one can object to them since they
fallaciously maintain that (1) if the perfection exhibited by one thing depends
on a cause, there is one thing that accounts for all things exhibiting degrees
of perfection, and (2) if something accounts for the tending to an end of
something lacking awareness, there is some one thing accounting for the tending
to an end of all things lacking awareness.
(e)
In the Five Ways, Aquinas always seems to assume that we should be looking for
agent causes. But why should we not take various things we know about to be
“just there” with no causal questions arising from them being so? Why not
suppose, for instance, that something undergoing change is just changing? Or
why not suppose that something in the world can just exist without us having to
look for a cause of its existing? And why not settle for the conclusion that
things lacking awareness tend to an end because that is just what they do? In
response to these criticisms I can imagine Aquinas saying:
(1)
The Five Ways do not purport to establish that God exists as being all that
those who believe in God take God to be. They purport to establish only that
there is something unchanged accounting for change, some un caused agent cause,
something necessary the existence of which is underived, something accounting
for there being things that exist and are good, and something accounting for
goal-directed activity on the part of things lacking intelligence.
(2)
The First Way does not invoke the premise that only what is F can bring it
about that something comes to be F, that, for example, one needs to be dead in
order to commit murder. And the principle of inertia should not be thought to
refute the point that something coming actually to be what it was before only
potentially does not bring itself into the state of actuality at which it
arrives.
(3)
While a per accidens series of agent causes might proceed to infinity, this
cannot be so when it comes to a per se series.
(4)
None of the Five Ways displays a quantifier shift fallacy. Their concern is to
argue that, given certain things we encounter, we need to suppose that there is
something accounting for them that is distinct from them.
(5)
The quest for an agent cause (or for several agent causes) is legitimate when
we are concerned with what does not have to be the case considered as what it
is, what it does, or what is happening to it.
At
least, I suspect that Aquinas would make these points and go on to develop them
in response to the criticisms of the Five Ways noted above. Whether or not he
might ultimately be successful in pressing them, however, is not a question
that I can try to discuss now. Instead, I must content myself with noting that,
having arrived at the end of 1a,2, Aquinas takes himself to have said enough to
show that we have good philosophical reason to think that God, understood in
the senses specified in the Five Ways, exists. As he moves on, he proceeds to
ask what God actually is and how our talk about God can be thought of as
latching on to God’s nature. Let us see what he has to say about this.
1.
When I say “much-quoted” I am really
thinking of 1a,2,3, in which Aquinas provides five arguments for believing that
God exists. The text of this article has been reprinted in translation
countless times. And it is often thought of as the best that Aquinas has to
offer when it comes to the question “Does God exist?” In the present volume I
try to introduce the text with an eye to its context.
2.
Aquinas defends this position in
Book I of his commentary on the Sentences and Book I of his Summa Contra
Gentiles.
3.
This line of thinking can be found
in the writings of some of Aquinas’s contem poraries, notably St. Bonaventure
(1217–1274). Cf. Question 1, Article 1 of his De Mysterio Trinitatis (Disputed
Questions on the Mystery of the Trinity). For an English edition of this text,
see Saint Bonaventure’s “Disputed Questions on the Mystery of the ture defends
all of the positions discussed and rejected by Aquinas in 1a,2,1.
4.
For an English translation of the
Proslogion, see Brian Davies and G. R. Evans (eds.), Anselm of Canterbury: The
Major Works (Oxford University Press: New York, 1998). For Anselm and the
Ontological Argument, see my “Anselm and the Ontological Argument” in Brian
Davies and Brian Leftow (eds.), The Cam bridge Companion to Anselm (Cambridge
University Press: Cambridge, 2004). For an account and discussion of the
Ontological Argument from Anselm onward, see Graham Oppy, Ontological Arguments
and Belief in God (Cambridge University Press: Cambridge, 1995).
5.
Cf. Graham Oppy, Ontological Arguments
and Belief in God.
6.
Davies and Leftow, 2006, 20. Aquinas
does not quote Anselm in connection with this argument, but he must have been
familiar with Anselm’s argument.
7.
Gaunilo (a monk of the Abbey of
Marmoutiers in France) replied to Anselm in a text called Quid ad haec
respondeat quidam pro insipiente (“A Reply to the Fore going by a Certain
Writer on Behalf of the Fool”). Anselm replied to Gaunilo in Quid ad haec
respondeat editor ipsius libelli (“A Reply to the Foregoing by the Author of
the Book in Question”). To understand how Anselm conceived of his “ontological
argument” one definitely needs to read his reply to Gaunilo. But this is
something to which Aquinas never refers.
8.
Cf. H. D. Lewis, Philosophy of
Religion (The English Universities Press Ltd: London, 1965), chapter 14. Here
Lewis speaks of knowing God on the basis of “cognition,” “insight,” and
“intuition.” He sums up his position by saying that God “is closer to all
things than distinct finite things ever are to one another” while adding “This
we see, not as inference, but in one insight or leap of thought” (146).
9.
Cf. P. T. Geach, Reason and Argument
(Basil Blackwell: Oxford, 1976), 18: “Bad logic books list ‘begging the
question’ as a fallacy. This objection, however, is a mere confusion, and in
the court of logic it should be denied a hearing: if the conclusion really is
implicit in the premises, then the argument is logically as good as it can
be—the conclusion really and indefeasibly follows from the premises.” It might
be suggested that people who know the premises of a valid argument can have no
use for the argument since they already know its conclusion. As Geach observes,
however: “This protest forgets that a man may know each premise, but never
happen to think of the two premises together and draw the obvious conclusion.”
Moreover, even with the premises before them, people vary very much in their natural
or acquired ability to derive conclusions from them; having the premises is no
guarantee that they will know how to derive the right conclusion” (18–19).
10.
I mention Barth again here since he
is an especially famous modern theologian with whom some readers of this book
might already be familiar. But in 1a,2,2, Aquinas, of course, is writing with
an eye to what he knew some of his predecessors and contemporaries thought.
11.
With respect to not knowing what God
is, Aquinas makes reference to St. John Damascene (ca. 676–749). I presume that
he is alluding to Damascene’s De Fide Orthodoxa, 1,4, which emphasizes the
incomprehensibility of God. Aquinas definitely takes Damascene to be a
Christian author to be read as authoritative.
12.
Davies and Leftow, 2006, 23. For a
text famously concluding that “it is wrong always, everywhere, and for anyone,
to believe anything upon insufficient evidence,” see W. K. Clifford, “The
Ethics of Belief,” in W. K. Clifford, Lectures and Essays, 2nd ed., edited by
Leslie Stephen and Frederick Pollock (Macmillan: London, 1886). This essay has
been frequently reprinted. It can be found in an edited form in my Philosophy
of Religion: A Guide and Anthology (Oxford University Press: Oxford, 2000).
13.
Davies and Leftow, 2006, 23 (with emendation).
14.
For a good essay on Aquinas on
“cause,” see Michael Rota, “Causation,” in Brian Davies and Eleonore Stump
(eds.), The Oxford Handbook of Thomas Aquinas (Oxford University Press: Oxford,
2011), 104–114.
15.
In all of the writings in which he
discusses the matter, Aquinas takes arguments for the truth of “God exists” to
be like this. To my knowledge, the best available account of Aquinas’s many
arguments for the truth of “God exists” is Fernand Van Steenberghen, Le Problèm
de l’existence de Dieu dans les Écrits de S. Thomas D’Aquin (Éditions de
l’institute supérieur de philosophie: Louvain-La-Neuve, 1980).
16.
For a good account of the Five Ways,
I would strongly recommend chapter 12 of John Wippel, The Metaphysical Thought
of Thomas Aquinas (The Catholic Uni versity of America Press: Washington, D.C.,
2000). An often-quoted critical discussion of the Five Ways is Anthony Kenny,
The Five Ways (Routledge & Kegan Paul: London, 1969). For a helpful
corrective to Kenny’s book, see Lubor Velecky, Aquinas’ Five Arguments in the
Summa Theologiae 1a 2,3 (Kok Pharos: Kampen, 1994); and C. F. J. Martin, Thomas
Aquinas: God and Explanation (Edinburgh University Press: Edinburgh, 1997). All
of the volumes just noted point readers in the direction of other secondary literature
on the Ways.
17.
This is the approach to God
expressed by the claim “Something must have started it all.” For a development
of it, see William Lane Craig, The Kalām Cosmological Argument (Macmillan:
London and Basingstoke, 1979).
18.
Aquinas sometimes speaks of the
effects of the first cause in a per se causal series as being “instruments” of
it. Cf. his commentary on Aristotle’s Physics, 8,9. Also cf. De Veritate, 27,4.
19.
For a good account of Aquinas’s
distinction between causal series ordered per se and causal series ordered per
accidens, see Scott MacDonald, “Aquinas’s Parasitic Cosmological Argument”
(Medieval Philosophy and Theology, vol. 1, 1991).
20.
Davies and Leftow, 2006, 24–25.
21.
By “real change” I mean a genuine
modification of an existing thing (as, e.g., is someone’s putting on weight or
sailing from the United Kingdom to the United States). We sometimes seem to
ascribe change to things where the change is not real change in this sense.
Thus, for example, we may say “Mary came to be ad mired by Paul” without
implying that Mary herself underwent any real change. This second sense of
“change” is not what Aquinas is thinking of in the First Way.
22.
This is not obvious from the text of
the First Way (which only invokes an ex ample of local motion). But note
Aquinas’s commentary on Book V of Aristotle’s Physics (Lecture 2) in which the
point is made clearly. The English word change can be rendered into (Aquinas’s)
Latin by both motus and mutatio. In his Physics commentary, Aquinas allows for
mutatio that is not motus while referring to what he calls substantial change,
which he thinks of, not as a change in an actually existing thing but as the
coming into existence of something or the passing out of existence of it (e.g.,
the generation or death of a human being).
23.
I use this example in order to bring
out the fact that Aquinas does not in general think that all change in a
subject is brought about by what is quite different from the subject. I might
be frog-marched into my kitchen by someone, but my coming to be standing in my
kitchen might also be explicable with reference to the movements of my legs,
which are parts of me.
24.
Davies and Leftow, 2006, 25.
25.
In the Second Way Aquinas does not
give any concrete examples of what he is thinking of when he speaks of
efficient causes and effects ordered in series. But he is definitely thinking
in terms of examples such as I give (while allowing that a number of efficient
causes and effects of efficient causes might be observed all together [as it
were])—as, when it comes, say, to a hand moving a stick that moves something
else (an example that Aquinas does give in the First Way).
26.
Anthony Kenny makes this point in
his The Five Ways (Routledge & Kegan Paul: London, 1969), 35–36. In his
Thomas Aquinas: God and Explanations, C. F. J. Martin speaks of the Second way
as a “generalization” of the First Way (146).
27.
Wippel, The Metaphysical Thought of
Thomas Aquinas, 459.
28.
Davies and Leftow, 2006, 25–26.
29.
Basically, Aquinas takes a substance
to be a naturally occurring thing, object, or being (as opposed to an
artifact). This sense of “substance” can be found in the writings of Aristotle.
According to this sense, dogs and cats, for example, would be substances
(though computers or telephones would not). For more on this, see John F.
Wippel, The Metaphysical Thought of Thomas Aquinas (cited above).
30.
For a discussion of people wrongly
interpreting Aquinas as saying that there has to be only one necessary being,
see Patterson Brown, “St Thomas’ Doctrine of Necessary Being,” reprinted in
Anthony Kenny (ed.), Aquinas: A Collection of Critical Essays (University of
Notre Dame Press: Notre Dame, 1976).
31.
When referring to contingency, some
philosophers have said that there are statements that are contingently true
because they are not true of logical necessity. On this account, “the Eiffel
Tower exists” is a logically contingent statement while “all triangles have
three sides” is a logically necessary one. With this distinction in mind it has
also been suggested that there is a corresponding difference when it comes to
things that exist contingently and things that exist necessarily—the idea being
that something existing contingently is something the existence of which can be
denied without self- contradiction while the existence of something necessary
cannot be denied without self-contradiction. As we have seen, Aquinas thinks
that the proposition “God does not exist” can be denied without the person
propounding it being guilty of self-contradiction.
32.
An argument to this effect can be
found in II,1 of The Guide of the Perplexed by Moses Maimonides (1135–1204).
This is a text with which Aquinas was familiar.
33.
The fallacy is sometimes called “the
quantifier shift fallacy” and is illustrated by the argument “All roads lead
somewhere, so there is some (one) place (e.g., Rome) to which all roads lead.”
34.
The interpretation of the Third Way
to which I am now referring supposes that Aquinas is assuming that if the world
has existed from infinity, perishable things in it would all have perished by
now. For Aquinas clearly denying that philosophy can establish that the
universe had a beginning, see John Wippel, Metaphysical Themes in Thomas
Aquinas, chapter 8. Aquinas develops this case in his De Aeternitate Mundi (On
the Eternity of the World). Cf. also Summa Theo logiae, 1a,46,2.
35.
I defend the second reading to which
I here refer in “Aquinas’s Third Way,” New Blackfriars 82, no. 968 (October
2001). Note that in his Summa Contra Gentiles (I,15), Aquinas offers an
argument strikingly similar to what we find in the Third Way. This argument is
clearly concerned with things coming to be rather than things coming to pass
away.
36.
Davies and Leftow, 2006, 26.
37.
I suspect that Aquinas would be
happy to say that a badly behaved cat (by a criterion of being well behaved
that we might have when thinking about cats) might be a very good cat (because
it is healthy). Aquinas frequently takes “good” to be an adjective only
understandable when it comes to the work it is doing as predicated of something
in particular. We might ask “Is X good?” Abstracting from things that he wants
to say about God’s goodness, Aquinas would reply, “I cannot answer the question
until I know to what you are referring by ‘X.’” He would mean that we commend
things as being good for different reasons and depending on what things we are
talking about and under what category we place them—that, for example, we might
say that Fred is a good parent but a bad doctor. When thinking about things in
the world, Aquinas takes “good” to be an attributive adjective and not a
predicative one. On this distinction, see P. T. Geach, “Good and Evil,”
Analysis 17 (1956).
38.
One can see him doing so in, for
example, De Veritate, 1,1. According to Aqui nas, being, truth, and goodness
are “convertible”—meaning that something exists only insofar as it is somehow
true and good.
39.
Again, cf. De Veritate, 1,1.
40.
I quote here from Davies and Leftow,
2006, 26 (with some emendation).
41.
Cf. William Paley, Natural Theology
(1802), chapters 1–3.
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