1
00:00:00,400 --> 00:00:06,480
Thomas Aquinas's famous work called the Summa Theologiae has three main parts. The first part

2
00:00:06,480 --> 00:00:12,640
deals with the presence of God in creation. The second part deals with the presence of God by

3
00:00:12,640 --> 00:00:19,520
grace in the souls of the just. And the third part deals with the presence of God in Christ

4
00:00:19,520 --> 00:00:25,840
and in his mystical body, the Church. The whole thing is really an extended meditation on the

5
00:00:25,840 --> 00:00:30,639
presence of God. But one of the greatest questions of all times is whether God exists.

6
00:00:31,440 --> 00:00:35,520
And Thomas takes the question head-on with his famous five ways,

7
00:00:35,520 --> 00:00:37,919
or five proofs, for the existence of God.

8
00:00:48,160 --> 00:00:51,119
In this episode, we will give a brief sketch of the five ways.

9
00:00:51,919 --> 00:00:55,680
But let us first ask how human beings can know the existence of God.

10
00:00:56,959 --> 00:01:02,400
One way to know God's existence is by taking it on faith from what the Bible says. But Thomas is

11
00:01:02,400 --> 00:01:08,480
well aware that the Bible itself tells us that there's another way to know the existence of God.

12
00:01:08,480 --> 00:01:15,120
In Romans chapter 1, verse 20, St. Paul tells us that the existence of God is known to everyone,

13
00:01:15,120 --> 00:01:22,160
at least in a general and confused sort of way, from the beauty and goodness of the natural world.

14
00:01:22,160 --> 00:01:27,519
And Romans chapter 1, verse 20, is a quick summary of a longer passage in the Book of Wisdom,

15
00:01:28,080 --> 00:01:34,879
chapter 13, verses 1 to 9. The two passages tell us to expect to find human beings who have never

16
00:01:34,879 --> 00:01:40,720
even read the Bible, but know that God exists just from their experience and rational reflection

17
00:01:40,720 --> 00:01:45,919
upon the natural world. Now, when Aquinas turned to the writings of ancient pagan philosophers,

18
00:01:45,919 --> 00:01:50,400
he found exactly that. He found people who had never read the Bible, but who had given

19
00:01:50,400 --> 00:01:54,800
serious arguments for the existence of God. The writings of ancient pagan philosophers

20
00:01:55,360 --> 00:02:00,559
confirmed the biblical teaching that it is possible for human beings to know the existence

21
00:02:00,559 --> 00:02:07,360
of God without ever even having read the Bible. For both of these reasons, Aquinas taught that

22
00:02:07,360 --> 00:02:12,399
human beings have a natural knowledge of God, or to put it another way, that we can know the

23
00:02:12,399 --> 00:02:19,039
existence of God by using our natural reason or human intelligence. That is the kind of knowledge

24
00:02:19,039 --> 00:02:25,199
we're exploring here, our natural knowledge of God. Now, Thomas did not say that our natural

25
00:02:25,199 --> 00:02:32,160
knowledge of God was always explicit, clear, or easy to come by. He did not affirm that the existence

26
00:02:32,160 --> 00:02:39,279
of God was undeniable. Rather, he thought of the natural knowledge of God as falling on a spectrum

27
00:02:39,279 --> 00:02:46,160
of cognitive development. Everyone has a common and confused knowledge of God's existence, but

28
00:02:46,160 --> 00:02:53,199
like any other form of knowledge, this common and confused knowledge of God is open to development

29
00:02:53,199 --> 00:02:58,880
for those who have the time, interest, and intellectual gifts for developing it. Thomas

30
00:02:58,880 --> 00:03:04,720
also realized that it was hard to develop our natural knowledge of God, and many factors stand

31
00:03:04,720 --> 00:03:13,119
in the way. Depending on cultural circumstances, people will develop it more or less, but generally

32
00:03:13,119 --> 00:03:21,119
not to its fullest perfection. But, he says, a few people, after a long time, and still with some

33
00:03:21,119 --> 00:03:27,520
errors mixed in, will develop their natural knowledge of God to such an extent that they

34
00:03:27,520 --> 00:03:34,559
can offer philosophically rigorous proofs for the existence of God, and answer all objections to

35
00:03:34,559 --> 00:03:41,360
those proofs with great dialectical skill. This is the task he takes up in the famous passage on the

36
00:03:41,360 --> 00:03:48,320
five ways, and in other more extensive writings of his on the topic. So, how exactly do we know the

37
00:03:48,320 --> 00:03:54,080
existence of God? The basic principle behind the five ways is that we know the existence of God

38
00:03:54,080 --> 00:04:00,479
from our experience of the world of nature, and looking for an ultimate explanation of it. We use

39
00:04:00,479 --> 00:04:05,119
the same kind of reasoning that we use when we know the existence of any invisible cause

40
00:04:05,119 --> 00:04:10,320
from visible effects. For example, if I'm driving down the freeway and see a billowing cloud of

41
00:04:10,320 --> 00:04:17,279
smoke coming up from the horizon, I can infer there must be a fire, even if I do not see the fire,

42
00:04:17,279 --> 00:04:23,200
even if it's blocked from my view. The fire is invisible, but the smoke it produces is not,

43
00:04:23,200 --> 00:04:29,119
and I know the existence of the invisible cause from the visible effect. Or similarly, if I wake

44
00:04:29,119 --> 00:04:34,239
up one morning with a sore throat, I infer that I have some kind of infection or virus. I do not see

45
00:04:34,239 --> 00:04:39,760
the infection or the virus. The cause of the sore throat is invisible, but I know that it's there by

46
00:04:39,760 --> 00:04:45,760
reasoning from the experience of the symptoms. So it is with our knowledge of God. What we see or

47
00:04:45,760 --> 00:04:52,640
experience around us is the natural world. God is invisible. We don't see him, but from what we do

48
00:04:52,640 --> 00:04:58,320
see and experience of the natural world, we can infer that something must be behind it all.

49
00:04:58,880 --> 00:05:05,279
Something is responsible for the greatness, the beauty, the order of the world. Aquinas thought

50
00:05:05,279 --> 00:05:10,640
that this inference from the order of the world to the existence of something responsible for

51
00:05:10,640 --> 00:05:16,959
the order of the world was so fundamental that nearly all human beings reason this way.

52
00:05:17,920 --> 00:05:24,720
But he also realized that this inference or argument was something like a seed. The seed can

53
00:05:24,720 --> 00:05:31,200
develop and grow through study and the application of the mind to the many philosophical issues

54
00:05:31,200 --> 00:05:38,880
involved in making the inference. But the seed can also be crushed by attachment to sin,

55
00:05:39,760 --> 00:05:46,000
willful self-denial, false philosophies, and other adverse conditions that ruin it.

56
00:05:47,200 --> 00:05:53,760
So we're not committed to saying that agnosticism and atheism are impossible. They might even become

57
00:05:53,760 --> 00:06:01,040
prevalent in some societies. But we are committed to saying that natural theology is possible for

58
00:06:01,040 --> 00:06:06,239
human beings. And Thomas Aquinas is an example of someone who developed this natural knowledge of

59
00:06:06,239 --> 00:06:13,359
God to an extremely high degree. What he did was take the general argument from the order of nature

60
00:06:13,920 --> 00:06:19,600
and think it through along much more specific lines. To spell this out, let us give a sketch

61
00:06:19,600 --> 00:06:25,600
of each of the five ways. In the first way, we start with our experience of the order in the

62
00:06:25,600 --> 00:06:32,079
motion or change of things around us in nature. And careful study of what motion and change are

63
00:06:32,720 --> 00:06:39,040
leads us to conclude that there must be a first mover or unmoved mover or an ultimate source of

64
00:06:39,040 --> 00:06:43,760
change in things. In the second way, we start with our experience of an order of cause and

65
00:06:43,760 --> 00:06:50,880
effect in things around us. When we reflect carefully on what causality is, we learn that

66
00:06:50,880 --> 00:06:57,040
in order for there to be causes at work, there must be a first cause or uncaused cause. In the

67
00:06:57,040 --> 00:07:02,799
third way, we start by considering the order of contingent beings, things that exist but do not

68
00:07:02,799 --> 00:07:09,839
have to exist. When we reflect on things that exist but do not have to exist, we naturally ask,

69
00:07:09,839 --> 00:07:16,320
why do they exist? This leads to the conclusion that there must be a source of the very existence

70
00:07:16,320 --> 00:07:23,760
of contingent beings, and the source cannot not exist. The source simply is. In the fourth way,

71
00:07:23,760 --> 00:07:28,799
we look at how things around us exist in grades of perfection, and the grades of perfection lead

72
00:07:28,799 --> 00:07:33,920
to the conclusion that there must be a perfect being, the source of being in everything else.

73
00:07:35,279 --> 00:07:42,559
And finally, in the fifth way, we find in nature that things without intelligence act for the sake

74
00:07:42,559 --> 00:07:48,720
of ends. Honeybees work to produce honey even though they do not have intelligence, properly

75
00:07:48,720 --> 00:07:56,079
speaking. Things without intelligence cannot work for the sake of an end unless a higher intelligence

76
00:07:56,079 --> 00:08:02,799
is directing them. This leads us to conclude that there must be a supreme mind or intelligence

77
00:08:02,799 --> 00:08:08,880
behind it all. Now what I have given here are just sketches of the arguments, and one can spend a

78
00:08:08,880 --> 00:08:14,480
lifetime considering all the issues surrounding them. But even the sketches give us a way to begin

79
00:08:14,480 --> 00:08:20,880
meditating on the presence of God in the world around us. God is present in things, moving them,

80
00:08:21,519 --> 00:08:26,720
causing them, giving them being, and directing the course of everything.

81
00:08:29,200 --> 00:08:35,760
For readings, podcasts, and more videos like this, go to Aquinas101.com. While you're there,

82
00:08:35,760 --> 00:08:40,880
be sure to sign up for one of our free video courses on Aquinas. And don't forget to like

83
00:08:40,880 --> 00:08:51,200
and share with your friends, because it matters what you think.