Christian Apologetics - Lesson 18

Possible Worlds (Part 2/2)

Something is logically possible if its description does not include a logical contradiction. The existence of the laws of knowledge refute the system of naturalism.

Ronald Nash
Christian Apologetics
Lesson 18
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Possible Worlds (Part 2/2)

Possible Worlds

Part 2

II.  Possible Worlds

A.  A possible world is a way the real world could have been.

B.  Possible Worlds and Logical Possibility

1.  Something is logically possible if its description does not include a logical contradiction.

2.  Logical possibility and physical possibility

C.  A possible world is a complete state of affairs.

D.  For every possible world there is a book about that world.

E.  Contingency and Necessity

1.  Contingent and Necessary Beings

2.  Contingent and Necessary Truths

F.  Essential and Nonessential Properties

1.  Every human being has nonessential properties.

2.  Essential properties exist in every possible world.

3.  God's essential properties are the sum total of his attributes.

4.  Fallacy of the Kenosis Theory

G.  Refuting Naturalism

1.  Naturalism denies the existence of anything outside the box.

2.  Need just one thing that exists outside the box.

3.  The laws of logic must exist outside the box.

4.  Arguments must conform to the laws of logic.

5.  The laws of logic must be necessarily true.

6.  Naturalism is logically self-defeating.

  • Introduction to Apologetics.

  • Apologetics involves finding evidence and presenting arguments to defend the Christian faith.

  • Two prominent worldviews are Christian theism and naturalism.

  • The law of non-contradiction states that A cannot be B and non-B at the same time and in the same sense.

  • Explanations and responses to different worldviews.

  • If God is good and all powerful, then why does evil exist?

  • Discussion about how the existence of evil is consistent with God's character.

  • Your noetic structure, presuppositions and view of epistemology are important elements in the formation of your worldview.

  • Discussion of deductive presuppositionalism vs. inductive presuppositionalism.

  • Objections to inductive presuppositionalism.

  • Arguments for and against evidentialism.

  • Arguments for and against foundationalism.

  • Discussion of natural theology.

  • There are valid, sound and cogent arguments for the existence of God, but no coercive proofs.

  • Discussion of different arguments for God's existence.

  • One version of the cosmological argument for God's existence emphasizes God as first in time, another emphasizes God as first in importance.

  • A possible world is a way the real world could have been. Modal logic, propositions, state of affairs and eternal entities are some of the considerations when discussing a possible world.

  • Something is logically possible if its description does not include a logical contradiction. The existence of the laws of knowledge refute the system of naturalism.

  • Middle knowledge is a form of knowledge attributed to God by Molina.

  • Miracles are a dividing line and central to Christianity.

  • David Hume's rational arguments against miracles and responses to those arguments.

  • Two miracles central to Christianity are the incarnation and resurrection.

  • The question of whether or not Jesus is the only savior touches on pluralism, inclusivism and exclusivism.

  • Pluralism is the view that all religions have salvific value.

  • Inclusivism is the view that even though the work of Christ is the only means of salvation, it does not follow that explicit knowledge of Christ is necessary in order for a person to be saved.

  • Salvation is totally the work of God and all children who die in infancy are elect of God.

  • Discussion from a biblical perspective of God's character and attributes.

  • Open theists believe that God does not have a perfect knowledge of the future.

  • Divine omnipotence and divine omniscience are two attributes of God.

  • When contemplating life after death, remember, Jesus has been there and come back. Will you commit your life to him or reject him?

These lectures were given at Reformed Theological Seminary in Orlando, Florida during the fall of 2001.


Dr. Ronald Nash

Christian Apologetics


Possible Worlds (Part 2/2)

Lesson Transcript


[00:00:01] Now. Page two. Well, I'm going to define a possible world. And I'm going to give you two definitions, but I'm only going to give you one at a time. Okay. Only going to give you here. Here it is. A possible world is, first of all, away. The real world could have been. A possible world is a way the real world could have been. Now, this little expression here, the real world is very important. Because whatever else we think or talk about possible worlds, we've got to have some linkage to the possible world that is the most important of all, namely the real world. Okay. Now, let me keep let me keep elaborating on this a little bit. I'm going to draw ten circles on the board. One, two, three, four, five, six, seven, eight, nine, ten. Okay. Each of these circles represents a possible world. But of all of the possible worlds that exist. And there are. Trillions of them. One day in a moment of foolish excess, I once said to students there may be an infinite number of possible worlds. And a member of that class who was a math major fainted. Math people who are trained in higher math today, they get very upset when people use the word infinity in a loose way. Okay. So I've stopped talking about there being an infinite number of possible worlds. In fact, I'll give you the exact number of possible worlds there are. Would you like that number? Okay. Ten to the 63rd power. That's how many possible worlds there are. Now, let me tell you why. That's a pretty safe number.


[00:02:24] And if any of you are trained enough in physics or something else to correct me and give me the right number, I'll be I'll be impressed. I have read. That if you took all of the molecules that exist in the entire universe, that number would be something like ten to the 56th power. Actually, I think it's a little less than that. So if that's the number of molecules in the entire universe, give or take. Several. Trillion or something like that. This would look to be a pretty safe number for the number of total number of possible world. And you know how you do this. You just write the number, you write the number ten, and you add 63 zeroes after that. So I no longer talk about an infinite number of possible worlds, only talk about ten to the 63rd power, a possible world. Here we have ten of them. We do not have time to write this number of possible worlds on the board. But this world is the real world. And every other possible world is a variation of variation, no matter how small of the real world. For example, right now I'm wearing. A nice shirt that my wife gave me or somebody gave me for Christmas. But instead of it being green, shovel shades of green and orange, it could be blue and red. So I could have worn how many other shirts? Kinds of shirts. I have my hair parted today in the middle. Okay. But you've all seen vain people who let their side hair grow very long and they commit to one side or the other. Anything that is slightly different from me. Notice I can put my watch on my right hand. See? If everything else in the world is the same except in this one.


[00:04:36] In this case, my my watch is on my right hand. We're we're dealing with a different possible world. Any any variation. Of a world. Brings you into the context of a totally different possible of a of a different possible world. Okay. So a possible world is a way the real world could have been. The second part of my definition of a possible world will. I'll give that a little a little later on. Okay. Now the next point. Possible worlds and logical possibility. This short paragraph is important because it lays out the major and the necessary condition that must be satisfied in order for any state of affairs to be part of a possible world. Let me just read this. This paragraph. This is to 13 the indispensable condition any state of affairs must meet in order to exist in some possible world is logical possibility. Nothing can be part of any possible world if it violates the characteristic of logical possibility. Now, here's the definition of logical possibility. Something is logically possible if its description does not include a logical contradiction. Something is logically possible if its description does not include a logical contradiction. Now, let's give you some examples. It is logically possible that Ted Kennedy has swum across the Atlantic. That doesn't sound right. I swam. Swamp. Okay. Now, notice we're not talking here about swimming across Chappaquiddick. Are you old enough to remember that we're talking here swimming across the whole Atlantic Ocean? Now, that's physically impossible. You see, there are two kinds of possibility. There is logical possibility, and something is logically possible if its description does not violate the law of non contradiction. If it is physically possible, then some human being can do it or some living thing can do it.


[00:07:02] Swimming across the Atlantic Ocean is not physically possible for any human being. Especially Ted Kennedy. I think even I could swim farther than Ted Kennedy could these days. Logically. However. Ted Kennedy can't swim across the Atlantic. Now it is the logical possibility stuff that gives us a possible world. Now, let me give you some examples of Ron Nash. Okay. There are possible worlds in which Ron Nash. Is the world's greatest golfer. Greatest pianist, greatest homerun hitter. All at the same time. And besides that, he's got the fullest head of curly blond hair of anyone you've ever seen. Barry Manilow in that world is jealous of Ronnie. I have an overhead. I'll have to bring it. It's a it's a picture of Ron Nash in another possible world. I'll have to dig that out. That's a classic. Okay. Many of you will be so overcome that you'll you'll you'll weep at how I look in this particular possible world right here. A lot of people are jealous of how I look in that possible world. No one is jealous of how I look in the real world, unfortunately. However, even though I can be the world's greatest homerun hitter and all of the rest in the same possible world, there is no possible world in which Ron Asch could square the circle. Why? Because squaring the circle is logically impossible. So the cynical known the absolute indispensable condition for being in any possible world is logical consistency. Now. So possible worlds and logical possibility. Nothing can exist in any possible world unless it is logically possible. There can be no possible world in which two plus two equals five. There can be no possible world in which the law of non contradiction is denied. Okay. Now what about physical possibility? Something is physically possible if someone can do it, but obviously physical possibility can vary from world to world.


[00:09:21] There really is a possible world in which I hold the world's record for running a mile and that particular possible world. I think I ran a mile in 58 seconds. I was tired when I got finished. Now. We're kidding here, You understand? We're not saying there really is a world like that. We're just saying if something's logically possible, you can refer to it by saying there is a possible world in which Ron Nash runs a mile and 58 seconds. Of course, it's physically impossible, but logically it's description does not violate the law of non contradiction. But consider an act that is logically impossible, such as squaring a circle. Since squaring the circle is logically impossible and it cannot occur in any possible world. And if something is logically impossible, then it cannot be physically possible in any possible world, including the real world. Now. Let me just elaborate on that. If something is physically possible in the real world. It can be physically possible in some other world. But if something is logically possible, it cannot be physically possible in any world. You must understand that. If something is logically impossible. In the real world, then it cannot be physically possible in any possible world. Squaring the circle is logically impossible. Therefore, there is no possible world in which anybody, including God, can square the circle. Now. Next point, a possible world is a complete state of affairs. This is the second part of my definition. A possible world is a complete state of affairs. This is very important. Let me draw a big circle here. And suppose this circle represents the entire history of the real world. That's this possible world right here. Incidentally, planning A gives the real world a name. He calls it Charlie.


[00:11:35] I'll I'm going to show my creativity here. We in this class, we're going to call the real world, Ronnie. Okay. I just feel more comfortable with a real world that is named after myself. Now, this big circle represents the entire scope, the complete state of affairs that represent Ronnie, the real world of which you and I are apart. Now, where does your whole life fit? Answer. Your life is just a slice. Of the possible world. That is the real world. It's just a slice of it. Take the Reformation. The Reformation. The Reformation is not a possible world. The Reformation is simply a slice of the whole possible world. That is the real world. I was once in New York City in order in order primarily to hear planning a given address at the American Philosophical Association about the time the planning was becoming very famous and he was going to read a paper on the problem of evil. And that was a very fascinating time because after planning, I gave his argument a Jewish rabbi who was in the audience jumped up on the table. Because one a planning is. Theses back then was. That's all possible. All evil in the world is a result. Evil either of human beings misusing their free will or of Satan and his minions misusing their free will. That was planning his position. Now, don't get too excited about that because there are some tricks in that matter and the poor Jewish rabbi didn't understand it. But the Jewish rabbi got so excited that he jumped up on the table and he started to jump up and down. He started he he said, Do you mean to tell us? Back to Plantinga. But you believe in a personal devil and demons and all of that nonsense.


[00:13:48] This was obviously a very liberal Jewish rabbi and planning who at that time was still smoking his little cigarillos, blew smoke in the direction of the Jewish rabbi and said, I never said that. I was only talking hypothetically, theoretically, about what happens in a possible world. And the and a lot of people have never yet to this day understood that planning is talking about this strange kind of possible world that we're dealing with. Well, after the meeting was over, I figured I'm going to go up and I'm going to give the smart aleck guy a hard time. You know, maybe I'll give him such a hard time that he'll recognize that I I've just refuted him. And he will get on his knees and ask me to forgive him for uttering such a stupid argument. So I said, Well, pardon me here. You know, with all due respect, you know, the Bible says that the saints in heaven will be completely free and yet will never sin in heaven. Now that's relevant to his lecture because he had said in every possible world, every human being will misuse his free will and in some way so as to commit an evil act. And I said, Well, heavens are possible world. And in heaven, every human being will be free. But no human being who is free in that possible world will ever sin. We will freely always do the right. See, and I know that if some of you had been there, you'd have made the same point to planning. Well, let me show you how intimidated planning I was by my statement. He looked at me with some contempt. I Did he blow smoke in my face? I don't remember. And but he said this.


[00:15:41] He said, Ron, I'm sorry, but that won't work because heaven is only a slice of a possible world. And with that, he walked away. And I'm like, Jerry Seinfeld or Cosmo Kramer, you know, What did he just do to me? Heaven is a slice, and I didn't get it. But here is this point. Heaven is not a separate possible world. It is a slice of this one and only true real world. All right. Now, it's a pretty big slice because it's eternally long, you know, And I don't know how to draw that picture. So let's just say here is heaven. That's a slice of the real world. But it's. It's it you know, it has no end. Now, planning his point was this You cannot refute his. Now, his his his point has other problems, but you can't treat heaven as though it is one of these possible worlds. Heaven is a slice of the real world that begins with creation. And the creation of man and the fall of Man and the redemption affected for us by Jesus Christ. And you can't get from the beginning to heaven without going through the fall and sin and everything else. Now, if you're with me, word on the next point to 14. For every possible world, there is a book about that world. Now, here is where things get interesting. I know that this stuff up to this point, we've been laying the foundation for it, but now we're going to begin to get some dividends from this. Okay. If a world is a complete state of affairs. Then the sum total of all propositions that refer to that world make up a book. Okay. Now, let me just explain. Because a state of of because a possible world is a complete state of affairs, you cannot add another state of affairs to it if you did.


[00:18:10] The state of affairs you tried to add to the world would would contradict some other state of affairs that already exists. It's complete. You can't squeeze another state of affairs in there. Well, likewise, if you if you begin to think about what we could call the book about a possible world. Okay, let's number these world. One, two, three, four, five, six, seven, eight. Let's think about the book on possible world ten. What is the book on A world On world ten. It is the sum total of all true propositions. About ten. That possible world. It is also the complete state of affairs that obtain impossible world number ten. Okay, now notice the book, because there is this huge number of possible worlds. There are a huge number of books about these possible worlds, but there is also the book about. The real world. Now, this may confuse you, but let's put it in theological terms. What is the book about the real world Answer? It is the sum total of all true propositions about our world, past, present and future as they exist in the mind of God. Do you see that? I know all this talk about states of affairs and everything can be confusing. But if you recognize that we are dealing here with a sovereign God who knows everything. The whole book about the real world. And also. The whole book about every other possible world. Now let's keep going. Possible worlds, contingency and necessity. Let's look, first of all, at contingent. Beings. Okay, Now I'm ready to give you some arguments for God's existence here. See where we're going to begin to get some payoff here. What is that contingent being? Well, first of all, let's get personal here. You. You are a contingent being all right.


[00:20:20] You are a contingent being. So am I. You know what a contingent being is? It's a it's a being whose nonexistence is who is is possible. A contingent being is of being whose nonexistence is possible. Now, if your existence had a beginning, someday you're a contingent being. If your existence can end, someday you're a contingent being. But there's another feature of a contingent being a contingent being as a being whose existence is dependent upon other things. And your existence and my existence is contingent upon temperature, oxygen, the absence of anthrax and all kinds of other things. So you and I are contingent beings. Now, here is how the notion of a contingent being relates to possible worlds. If you are a contingent being, then there are some possible worlds in which you do not and cannot exist. In my case, for example, I exist in the real world. There I am. And that's a good world to exist in. Do you understand? But I also exist in World three and possible worlds. Six and possible world ten. But I do not exist in many. There are many possible worlds in which I do not exist. Can you imagine how impoverished those worlds are? Can you contemplate a possible world without me? Well, they exist. As do worlds without you. Okay. But now. Unnecessary. Being is a being an entity that exists in every possible world. Contingent beings exist in only some, but not all possible worlds. Unnecessary being exists in all possible worlds. All right, now let's. Let's tick off some necessary beings. The number one. Is a necessary being. The number one exists in every possible world. Glory. God. Is unnecessary being. God exists in every possible world. He is a necessary being. Okay.


[00:22:53] Let's talk about contingent and necessary troops. A contingent proposition is true in some possible worlds, but not all. The proposition Ron Nash was born in 1936. That's true in the real world. That may be true in lots of other possible worlds, but there are other possible worlds in which it's not true. There are possible worlds in which I was born in 1852. And there are possible worlds in which I was never born. A what are some necessary truths? Two plus two equals four is a necessary truth. What does that mean? That means this proposition is true in every single possible world. That means that even if there were alien life on other planets. The Proposition two plus two must equal four in their world. Okay. There is no possible world in which the sum of two plus two could equal anything other than four. Okay. Three times three equals nine is true. Necessarily true. True in every possible world. Does that have implications for postmodernism? You bet it does. Postmodernists cannot make peace with the doctrine of possible world. That means they've got to be hundreds of years behind. You know, they're not cutting edge like you and I are. See? Now also, let's talk about essential and non-essential properties. Essential and non-essential properties, everything that well, let's just talk about human beings here. Every human being has non-essential properties. Baldness as a non-essential property. That means that there are possible worlds where Ron Ash exists. We know that he exists in one world one, three, six, ten, and, you know, millions of other possible worlds. But because baldness is not on a central property, there are possible worlds out there in which I've got a full head of red hair, a full head of blond hair.


[00:25:13] There are possible worlds in which I'm ten feet tall. Some possible worlds in which I'm two inches tall. Don't make any funny jokes about that. Okay. But in every possible world in which Ronnie Ash exists, he possesses his essential properties, as you do. And what is the essential property that Ron Nash possesses in every possible world in which he exists? Nastiness. Now let's relate this to God. Does God have essential properties? Yes. And what are the essential properties of God? The sum total of all of His attributes omnipotence, holiness, omniscience. What that means is that since God exists in every possible world, because He is a necessary being, then in every possible world, God also possesses all of His essential properties, His attributes. Now in here lies one of the one of the major fallacies of the Kenosis theory. The closest theory, you know, is the idea that at the Incarnation, the Eternal Son of God gave up some of his attributes. He gave up his omniscience. He didn't know what was going to happen to him at the next at the same time and so on. But the problem with the Kenosis theory is this If there is a possible world in which Yahweh, God gives up any of His essential attributes, he ceases to be God in that world. And that's impossible. Therefore, the Kenosis theory entails a logical absurdity. That God could abandon an essential property. That cannot happen. Now, one other question. God has essential properties. Does God possess and boy, do I get up. Always get a bundle of different answers to this. Does God possess any non-essential properties? Well, I'll tell you the truth. All right. Yes. God possesses some non-essential properties, which means that even though God's attributes are a part of his eternal essence, in every possible world, there are nonessential properties of God that that are not part of God's nature in in some possible worlds.


[00:27:57] And here are some examples. Okay. God's being creator of heaven and Earth is not an essential property of God. You want to think about this, but let me tell you why that's true. Listen to this. If being the creator of heaven and Earth were an essential part of God, an essential property of God. Then we'd be stuck with pantheism. Pantheism. Listen, you be very suspicious of anybody who suggest to you that God had to create the world. No, he didn't. He created the world freely. He didn't have to create the world. And that idea of necessary creation is a part of pantheism, because that makes the world and God inseparably linked. That's heresy. Okay, here's another non-essential property of God being Lord of Israel. God chose Abraham. God chose to be the Lord of Israel. But he didn't have to. He didn't have to create Israel. He didn't have to create Abraham. He did. But he didn't have to. See, that's that's a nonessential property of God. So his eternal attributes are properties of God in every possible world in which he exists. But his non-essential property, such as being Lord of Israel, being creator of the world. Being the savior. Of Ron Ash because he didn't have to make me. He did not have to make me. And we already know that there are possible worlds in which I don't exist. And you don't exist. Okay. All right, Now let me talk about naturalism. This is page 219. This doctrine of possible worlds can help you understand the basic refutation of naturalism that appears in. In Chapter 18 of the Faith and Reason book. Okay. Chapter 18. Now, let me tell you what Chapter 18 is all about. In chapter 18. I tell you that the real reason why anybody rejects miracles is because that person's worldview will not allow them to believe in the possibility of miracles.


[00:30:34] And then I follow C.S. Lewis, who, to my knowledge, was the first guy to develop this particular kind of argument against naturalism. It has since been picked up by Philip Johnson. It has been picked up by Alvin planning a. And it has been picked up by me. But I have already told you I'm following C.S. Lewis. Both Phillip Johnson and Alvin planning of say that they never read it in C.S. Lewis. They were surprised after they published their own versions of this reputation that it had first been used by C.S. Lewis. Here's C.S. Lewis's argument. And I'm going to relate it to the possible worlds stuff. Here's naturalism again. It is a closed box. And naturalism denies the existence of anything that is outside the box. There's nothing out here, and the box is the physical universe. It is nature. And a naturalist believes that if anything exists, it must exist inside the box. If anything happens, it must be caused by something else that exists inside the box. C.S. Lewis argued like this All you need to refute naturalism. Is just one thing that exists outside the box. Why? Because the essence of naturalism. The thesis statement. The touchstone proposition of naturalism is nothing exists outside the box. Therefore, if you can prove the existence of just one thing outside the box, you have refuted naturalism. That's C.S. Lewis in his great book, Miracles. Read it. Now, once Lewis has made that point, he says, how do you prove the existence of anything outside the box? Very simple, he says. I'll prove to you the existence of something that every naturalist must admit exists outside the box. And what is that one thing that exists outside the box? Answer the laws of logic. The laws of logic.


[00:33:06] Now, notice here I've drawn a line that begins inside the box. But that line must transcend the box. It must exist beyond the boundaries of the box. It must, in a sense, transcend nature. Why? Two reasons at least. Reason number one. Every naturalist believes that he can prove the superiority of naturalism to any other competing worldview. But he cannot prove the superiority of naturalism unless his arguments conform to. Necessary and transcendent laws of logic. You see, everything that exists inside the box is contingent. But the laws of logic cannot just be contingent. The laws of logic must be necessarily true. Otherwise, the guy can't use them to prove his naturalism. Now, in the old days before I had published this chapter, whenever I gave this shorthand refutation of naturalism, students would come at me in this way. They would say, Look, Nash, there are all kinds of things. There are all kinds of laws in the universe. There are the laws of physics, for example, but the laws of physics don't prove the existence of God, nor do they prove the falsity of naturalism. And I would keep saying to students, You're right, but there's a difference between the laws of physics and the laws of chemistry, and the laws of biology and the laws of arithmetic and the laws of logic. The laws of the laws of physics are contingent. They cannot exist outside the box, but the laws of logic are necessary. They must exist outside the box. Otherwise, the naturalist has no way of arguing for the superiority of his naturalistic worldview. Now, how does that how does the language of possible worlds prove that? All right, Here are our ten possible worlds. Okay? The laws of physics, chemistry and biology exist only in some possible worlds, but not all.


[00:35:42] There is nothing logically necessary about the laws of physics, but the laws of logic, the very laws that the naturalist must appeal to when he attempts to prove the superiority of his position. They must exist in every possible world. Therefore, they must exist beyond the boundaries of the box. Therefore, the naturalist is involved in cheating. He is denying the transcendent existence of something that he must appeal to in order to support his belief in naturalism. Therefore, naturalism is a logically self-defeating position. And with that information, that important move in C.S. Lewis, whose reputation of naturalism son suddenly becomes as clear, clear as day. All right. If you understand what we've been doing here. Thank you for listening to this lecture. Brought to you by biblical training, dawg. Your prayers and financial support enable us to provide a biblical and theological education that all people around the world can access. Blessings. As you continue to study and live out your faith and as you grow in your relationship with the Lord.