THE AGE OF INTELLIGENT MACHINES | A Platonic Dialog on the Nature of Human Thought

September 24, 2001
author |
Ray Kurzweil

Asmenides: Greetings, Kurzus. I have ventured far to meet you and to hear of your ideas on philosophical systems. You have a distinguished reputation among my people but have unfortunately created many enemies with your ideas. I have even heard some rumors of your disbelief in the existence of any supreme being or God.

Kurzus: My son, I am afraid that I have been misinterpreted. Let me first define what I mean by a philosophical system. Consider the following example of such a system. Is it not possible that the only thing that actually exists is your mind and everything that you perceive and think is merely fantasy, like a continuous dream?

Asmenides: That sounds like fantasy to me.

Kurzus: Well, how do you know that what you see and feel really exists as something other than your sense impressions of it?

Asmenides: For one thing, other people looking at the same building generally see the same thing. There must, therefore, be something that is the building apart from the images of it.

Kurzus: Is it not possible that you merely imagine that other people exist and tell you that they see the same thing you see when you look at the alleged building?

Asmenides: This all seems very possible, but you cannot really accept such a belief?

Kurzus: Whether I accept it or not is inconsequential. This is merely an example of a working philosophical system, perhaps the simplest example. We make certain assumptions, and if through logical deductions they lead to no contradiction, then we say that we have a logical system. We may have any number of systems, and the most we can say is that any one of them is possible.

Asmenides: It seems to me that you can make any wild assumption and end up with a logical result.

Kurzus: Ah, but there is where you are wrong. Imagine that we take as assumptions things that we naturally assume to be true in our every day life and end up with a contradiction. This is where the true power of this method comes in. We have proved with complete assurance that the system described by these assumptions cannot exist! I have found, however, a number of systems that do seem to work. When I discuss such a system, it does not mean that I necessarily believe that this is the way things are; I mean merely that it could be this way. I have found some systems that work with a God or gods and some that work without.

Asmenides: Well, what about our religious system, have you found any contradictions there?

Kurzus: I undoubtedly could find some. I imagine a system could be developed that would incorporate many of the ideas in our religious heritage, but it would be a somewhat arbitrary system. The fewer assumptions a system makes, the more powerful are its conclusions.

Asmenides: My father would beg to differ with you.

Myronius walks by.

Kurzus: No doubt, but consider the nature of the soul.

Myronius: Please forgive me for interrupting, but I could not help but overhearing. I am, perhaps, more skeptical than either of you gentlemen, but how do you know there exists such a thing as a soul?

Kurzus: Let us first accept as a definition of the soul something metaphysical that we associate with a person, animal, or object. I admit this is a poor definition, but we shall have to accept it until we find out more about the necessity of introducing a soul.

Myronius: You are defining something that may not exist. I contend that everything can be explained via the physical world.

Socrates: Myronius, are you mad? Have you learned nothing from my teachings? This is certainly not like you.

Myronius: Please forgive me for expounding a philosophy so heretical, but what I meant to say was that I believe a logical system, as described by my friend Kurzus, can be developed in the realm of the physical world. This system would describe and account for all of the phenomena that we are familiar with. I also contend that such a system would be a determined system. In other words, I believe that in such a system the future would be fixed and already determined.

Socrates: This should be interesting, but proceed.

Myronius: Witness our colleague Asmenides, and imagine, if you will, that I cut him in half.

Asmenides: I suggest that we skip the demonstration.

Myronius: That is too bad, it would have been so much more effective, but if you insist, we shall rely on our minds, a precarious course, I admit. Now imagine, gentlemen, that I remove one bone and cut it in half. Do you, Socrates, believe that we should still have bone matter?

Socrates: Apparently.

Myronius: And if we broke this piece of bone in half again, would we still have bone?

Socrates: This is all very true, although I fail to see any connection.

Myronius: And if we continue this process, would we always have bone?

Socrates: I imagine we should have to stop eventually.

Myronius: Then you admit that we would come to a point where we would have an elementary particle of bone that could not be severed without losing the properties of bone.

Socrates: I have had similar thoughts, yes.

Myronius: And would this not be true of all things?

Socrates: You have learned the art of argument well, Myronius. Yes, I imagine it is true for all things.

Myronius: Then there must be a finite number of fundamental particles of which the world is constructed.

Socrates: For the physical world, I will accept such a theory.

Myronius: Now imagine, if you will, the following machine, which I shall draw in the sand.

Myronius draws a simple machine with a lever and a pulley.

Socrates: You have an imagination not unlike your father.

Myronius: If I were to drop the ball on the lever, would you expect the weight to move?

Socrates: I imagine it would rise.

Myronius: We can imagine the ball and the weight to be two fundamental particles. The motion of one causes the other to move in a distinctive and quite predictable manner. We can define the lever and the pulley to be an “ether” through which the particle of the ball affects the particle of the weight. Analogously, can we not make the same claim with respect to the interaction between our real fundamental particles?

Socrates: I see no reason for such a claim. Do you imagine that there is such a system connected between all the fundamental particles in the universe?

Myronius: Certainly not, but is it not true that particles do interact? Otherwise, how would the pressure of my hand against this column cause it to move?

Asmenides: Careful, the whole house is liable to fall.

Myronius: And were it to fall, would it not have been caused by the interaction of the particles of my hand with the particles of the column and their subsequent interactions with the particles of the rest of the house?

Socrates: Yes, I can see what you are driving at now.

Myronius: There is apparently an ether, much finer and subtler, of course, than the ether of the pulley and string, that establishes a cause and effect relation between the fundamental particles. Do you not suppose that given the makeup of the ether and the location and speed of all the fundamental particles, we could predict the subsequent location and speed of all the particles at any time in the future?

Socrates: It would be an arduous task but theoretically possible.

Myronius: Then is it not true that any future state of the universe is already defined?

Socrates: As to your contention that a completely physical world is determined, I will agree, but please show me how everything can be explained in terms of the interactions of particles.

Myronius: Well, it is obviously true for lifeless objects. As for men and women, could it not be possible that we are merely a vastly complex collection of particles that interact with each other and the particles of other beings and objects?

Socrates: Come now, this is hardly credible. What of reason and memory, not to mention desire?

Myronius: Imagine, if you will, that we remember things by changing the relative locations of a number of memory particles, and that the retrieval of this memory and all of the logical manipulations constituting reason that we make with our memory and immediate sense impressions are also complex arrangements of particles whose interactions define what we say, do, and feel.

Socrates: Then why does my student Akrios sometimes greet me with a nod of the head and sometimes with a more wordy greeting?

Myronius: What your pupil does, is, as I said, a function not only of the situation but of the internal states of all of his particles. Since Akrios learns something every day and gains new memories, he is not exactly the same person each day and can be expected to act differently. Do you not suppose that if we placed a person in a situation, noted his reaction, then somehow returned him exactly to his internal state before the experience and replaced him in the same situation, he would act in exactly the same manner?

Socrates: Yes, I suppose this is so, otherwise he would not be the same person if he had reacted differently. There does seem to be something missing in your analysis, however.

Kurzus: Perhaps I can help. How, Myronius, do you explain consciousness with your system?

Myronius: Just what do you mean by consciousness?

Kurzus: Simply my awareness of my own existence, what happens to me, and how I react.

Myronius: Well, I would admit to the existence of this consciousness or awareness if you defined it in the following way: an ability to associate the information introduced by the senses and to translate it into physical motion and speech.

Kurzus: That is not exactly what I mean by “consciousness.” What you have described-isn’t that an automatic reaction?

Myronius: Surely!

Kurzus: Then couldn’t a machine like the one you described, only more complex, be made to act just like you?

Myronius: Yes, and it would be me.

Kurzus: But this machine would not have an awareness of itself, it would be just like the machine you described in the sand.

Myronius: Yes, of course it would, that is all I am, a complicated machine, a collection of particles.

Kurzus: But you are different from a machine in one respect: you are aware of yourself and what is going on; the machine is not. You go through life, and all the time there is a “screen” on which you see or feel impressions of either reality or fantasy, it does not matter which in this argument. A machine would not have this property. It would receive visual impressions and immediately process and record them without realizing what was happening. Does the machine that was made to simulate you realize what is happening?

Myronius: If it were constructed in the same manner in which I am constructed, I see no reason why it would not be aware of things in the same way I am aware of things.

Kurzus: Let me take another example. Will you grant me that theoretically, a machine could exist that could reproduce any object placed under it?

Myronius: For the sake of your argument, I will grant such a marvel.

Kurzus: Then imagine yourself placed in such a machine and a copy of you, particle for particle, is produced one hundred lengths away. Would both “persons” be you?

Myronius: I said they would.

Kurzus: Well, how could you have a consciousness (or should I say “an awareness”?) of what is in the minds of two persons one hundred lengths apart?

Myronius: I wouldn’t. Each of us would have an awareness of our own. We are two different people with no possible connection between us.

Kurzus: But you said they would both be you. How could they both be you and yet be different?

Myronius: I don’t know, but I am not convinced yet.

Kurzus: After walking into the machine here, where would you expect to come out, here or one hundred lengths away? Do not forget that both persons will claim to have lived the same lives, then walked in here and walked out either here or there.

Myronius: I don’t know where I would walk out, certainly somewhere, but what is your point?

Kurzus: My point is simply this, that there exists a consciousness in every person, and that this consciousness cannot be defined by particle interactions. To clarify the point a little, I will say that I do not really know that anyone has consciousness but myself. Everyone else may exist only in my mind, or they may exist as automatic machines, but I do know that I have this consciousness. For the sake of argument, however, let us assume that all of us gentlemen here are conscious.

Myronius: I am vaguely understanding your point, but I still do not see why this consciousness cannot be explained by physical interactions.

Kurzus: When you see something and then store it in your memory, are you aware of the exact process of particle interactions that codes the information, relates it to previous memory, and stores it?

Myronius: No, I cannot say that I am aware of the mechanics of this process.

Kurzus: And are there not a number of processes that go on in your mind that you are not aware of?

Myronius: Yes, I suppose there are.

Kurzus: Let us call the preconscious mind whatever takes care of all these processes of which we are not aware and the conscious mind whatever does things of which we are aware. Is there any fundamental difference between these two minds, other than the things they deal with?

Myronius: I do not imagine there is any difference between the general principle of their construction.

Kurzus: Is there not, however, a difference between them, an important difference, namely that you are aware of what is going on in one mind and not in the other?

Myronius: Yes, there is that difference.

Kurzus: And wouldn’t you say that this difference is the consciousness we have been speaking about?

Myronius: I see. Then consciousness is the real me, and its function is to be aware of what is going on in my conscious mind.

Kurzus: Essentially, and that is a reasonable way of putting it. Now, you yourself have said that there is no physical difference between the conscious and nonconscious or preconscious mind, and since we have agreed that the difference between them is consciousness, must we not conclude by a simple step of logic that consciousness is not physical. Rather it is to be placed in a category separate from particles and their interactions?

Myronius: I will have to admit defeat.

Socrates: Your thesis is very interesting, Kurzus, but what other characteristics would you attribute to the soul?

Kurzus: We have defined the soul as something metaphysical. The physical world can be defined as all processes that can be described by particle interactions. We have previously argued that memory and the logic constituting wisdom can be described as an automatic process involving complex interactions of particles.

Socrates: The argument was given, but it was not convincing. How can a machine have the many skills of perception and reasoning possessed by men?

Kurzus: Examine again our simple example of a machine. The machine has one possible “sense.” It was activated by dropping the ball on the lever. It had one possible “reaction,” that of raising the weight. When the ball was dropped, it would go through a logical process and raise the weight. A human being has many senses, all of which are considerably more complex than that of the lever. We too can react in a multitude of ways. We produce reactions that are related to the state of our senses. If we had sufficient knowledge, we could describe the connection between different reactions and their related sense and memory states. Certainly, then, a machine could be constructed that could produce similar reactions to the same external conditions. After all, human beings do not have mysterious reactions. We talk and move in ways that can be described with reasonable precision. Since wisdom and memory, which are the names we give the processes connecting sense impressions to reactions, can be described in cause and effect terms, they fit our definition of belonging to the physical world and are therefore not metaphysical. The soul, therefore, is synonymous with consciousness, since it is our only metaphysical function.

Socrates: Do you mean to say that the soul does not contain wisdom or courage or temperance? What happens to the soul after the body dies? What does it have to be conscious of then?

Kurzus: Let us examine again just what properties the soul has. It has no power of reason or of memory, since these are physical processes. It is essentially the real person that is aware of what is happening to his body and mind and how they react. It makes no difference whether a given body has a soul or not to anyone except that person. There is no possible way of finding out whether someone or some animal has consciousness. It is apparent only to its possessor. We can differentiate two things as comprising a person. There is the material person, which includes his personality, memory, physical makeup, and so on, and there is the soul, which has no characteristics. All souls are the same, and yet they are different, just as two stones can be exactly the same and yet be different stones by virtue of their different locations. Souls, of course, do not have locations, as they do not belong to the physical world. They are merely associated with a particular person or thing. It is even possible for a soul to be associated with the simple machine drawn here in the sand. It would make no difference to us or the soul, since the soul would have little to be aware of. There is no reason to suppose that the soul disperses when the body dies. It may be placed in a newborn baby’s body. It would not remember its past life, since the soul has no memory.

Socrates: This is an absurd system. How do you know that these souls don’t change bodies every three minutes? It would, according to you, make no difference. If all of a sudden my soul were to become associated with your body, I would think that I had always been you, because I would have access to a memory of continuous past.

Kurzus: Very good. Do you have any other suggestions?

Socrates: Well, who or what do you suppose decides which soul goes into which body or animal?

Kurzus: If my body is not the only body with a soul, there is obviously a process that directs souls to bodies. I certainly have no knowledge of the politics of this process. If it is a conscious being taking care of the assignments, we can call this being God. We can even fit your philosophy of Forms in this framework very easily. Suppose, as you do, that the Forms of justice, virtue, wisdom, and so on, exist. We can suppose that this God has a perfect knowledge of these ideals and judges people as to how they live according to these Forms. He could then assign the souls of virtuous bodies to live again in some comfortable state and the souls of sinful bodies to live again in the body of an appropriate animal. This is, of course, an arbitrary system and may or may not exist.

Asmenides: Kurzus, in the system we have been discussing, the soul is metaphysical consciousness and has no other characteristics or abilities. Does this system necessarily describe reality, or is this merely an example of just one of your many possible logical systems?

Kurzus: No, it must be so. We have proved that consciousness does exist, and we have also shown that it cannot be explained in terms of the physical world. We have also determined that wisdom and memory can be explained by the physical world and therefore belong to it. We are left with no other alternative than the conclusion that the real person is his or her metaphysical consciousness, which we can suppose to be immortal. From this point on, we can make any number of hypothetical systems. We can assume that all men and women have souls, or we can assume that only we have souls, or we can assume that every living and lifeless object has a soul. Note that if a lifeless object had a soul, the soul would not know about it.

Socrates: I see an important contradiction in your system. Tell me, would there be any free will in your system?

Kurzus: Apparently not. You would have free will to do what you want or decide to do, but what you decide to do is determined. In other words, if we were given the makeup of the particular ether and the location, velocity, and other properties of all the particles that make up all the bodies and all the inanimate objects that make up the universe, we could predict the location and speed of all the particles at any future time. Since what we do and think is the sum of the motions of all these particles, everything we do is determined. We think we decide to do something, but really, we merely observe certain aspects of the logical process used in arriving at the decision. The existence of souls does not change this deterministic universe, because souls do not affect particles in any way, they merely observe. To convince yourself of the possibility of no free will, consider a dream. While you are dreaming, it certainly seems that you have control of your own actions, that you are making decisions. Upon awaking, however, we often discover that we had no real control, that it was “just a dream.” We had awareness merely of the processes behind our dream “decisions.” It is apparently the same way in the waking state.

Socrates: Then the future is as fixed as the past.

Kurzus: True.

Socrates: Then we could consider time as a fourth dimension, just like the three dimensions of absolute location, since just like absolute location, both directions in time are uniquely defined and fixed.

Kurzus: That would be a satisfactory way of looking at it.

Socrates: Then, theoretically, it should be just as possible to go back and forth in time as it is in the other three dimensions, since time is merely another fixed dimension.

Kurzus: Yes, the universe is one static unchanging four-dimensional picture, and it should be theoretically possible to go back and forth in time, although I know of no way to accomplish this feat presently.

Socrates: If I went back in time and killed my great-great-grandfather, could I not conclude that my great-grandfather would never have been born?

Kurzus: Yes, I imagine that would be so.

Socrates: Then in a similar manner we can conclude that my grandfather would never have been born, and so with my father and thus I would not have been born.

Kurzus: That is true.

Socrates: But, if I had not been born, I could not have gone back in time and killed my great-great-grandfather, and thus my great-grandfather would have lived, and I too would have lived, and I would have been able to kill my great-great-grandfather, and thus I would not have existed, and so on, ad infinitum.

Kurzus: Yes, I see the problem.

Socrates: Therefore, time is not like the other three dimensions. As we have seen, there is a logical proscription against moving in it in more than one direction. The only way, however, for it to be different from the other three dimensions is for it not to exist in a definite form in either the future or the past. Since we know that the past does exist in a definite form, we must conclude, therefore, that the future is not determined. This would imply free will, would it not?

Kurzus: Yes, I suppose it would.

Socrates: Since we have defined the physical world as the predictable interactions of particles, we have to assign free will as a property of the soul. Now if we add free will to the soul, would we not have to add logic and memory in order to make decisions that are not entirely arbitrary?

Kurzus: Yes, I imagine that would be necessary.

Socrates: Thus, we end up with a soul that has not only consciousness but also free will plus wisdom and memory. We might as well add courage and temperance.

Asmenides: I see a contradiction. First you, Kurzus, proved that logic and memory must reside in the physical mind and not in the metaphysical soul. Then you, Socrates, proved that logic and memory must reside in the metaphysical soul. Apparently our initial assumptions led to a contradiction and must, therefore, be wrong.

Kurzus: My only initial assumption was that I am aware of my own existence. Logic and memory can be defined as what I think about, or rather what I am aware of. To deny this assumption would be to deny either my awareness or my existence. I know that there is awareness of something. I can only conclude, therefore, that I do not exist. This is not an entirely satisfactory result.

Asmenides: Now you can see, gentlemen, that no system can work without gods. There are apparently gods that are able to resolve these dilemmas. We are probably tricked into contradictory conclusions in order to keep us from contemplating what is above our power to understand.

Kurzus: I see no reason for resorting to such mysticism.

Socrates: My friends, it is time that I take leave of you. I will think more of this discussion, and we can resume it again soon. It has been a most profitable afternoon.