
Originariamente Scritto da
spq
Un contributo, più serio di quanto può sembrare, tratto da:
Raymond Smullyan:
THIS BOOK NEEDS NO TITLE
Prentice-Hall, Inc. - Englewood Cliffs, New Jersey
Determinism or Free Will?
Scene l
Existentialist: But you shouldn't make such a promise. You
have no way of knowing that you will keep it inthe future.
Victim: What the hell are you talking about? Of course I
will keep it in the future!
Existentialist: But how do you know you will keep it in the
future?
Victim: Because I have decided to keep it in the future.
That's how I know!
Existentialist: I do not deny that you now honestly intend
to keep your promise. It is just that I do not see how your
present good intention can possibly guarantee that you will
have equally good intentions in the future. After all, there is
such a thing as changing one's mind!
Victim: Not with me there isn't! I never break promises!
Existentialist: How do you know that?
Victim: I have never broken a promise in my whole life!
Existentialist: I believe you. I don't doubt that for a moment.
If you tell me that you have never yet broken a promise, I
take your word implicitly. But just because you have never in
the past broken a promise, why does it follow that you never
will in the future?
Victim: I really don't understand you at all! Are you taking
a completely deterministic or fatalistic position? Is it as if it
were already "written in the book" how I will act in the future,
and since I don't know the "book," I have no way of knowing
what the future will be? In other words, are you trying to tell
me that 1 have nothing to say in the matter?
Existentialist: No, no; I am not saying that at all. I happen
to believe in free will. But strangely enough, free will is not the
crucial issue here. That is to say, a strict determinist would
come to the same conclusion I would, only for very different
reasons. The determinist would say that whether or not you
keep your promise in the future is strictly determined by the
laws of physics together with the present configuration of the
universe, and since you do not know enough about the present
configuration, then you have no rational means of knowing the
future. The determinist would thus say, "It is not up to you
whether you keep your promise or not; it is up to the universe
and its laws." I, on the other hand, believe in free will and
hence believe that at any time it is up to you what you do at
that time. You have now made a promise of your own free will.
You presently intend to keep it. But I do not believe that you
have the power to choose now what you will choose to do in the
future.
Victim: But I do have the power! I told you I have never
before broken my word. Does this not constitute very strong
probabilistic evidence that I will not break my promise in the
future?
S
Existentialist: Oh, probabilistic evidence! I wasn't thinking
ofthis at all! I thought you were claiming it a certainty that you
will keep your promise. If all you are talking about is probability,
then I'm not sure I would disagree with you. Indeed, the
fact that you have never yet broken a promise is in itself a good
probabilistic indication that you won't in the future, though
perhaps other relevant factors should be taken into account. At
any rate, if all you are saying is that it is likely that you will
keep your promise, I will not dispute you. All I object to is your
absolute certainty that you will keep your promise.
Victim: Of course I am certain! It's not a mere matter of
probability; it's a question of complete and total certainty. You
forget that it is I who have made the promise. There is no
power in the entire universe which can force me to break my
promise.
Existentialist: I know that no power in the universe can
cause you to break your word. I know that full well. You are one
of the most strong-willed, self-willed people I have ever
known-indeed, many would characterize you as downright
"stubborn." And therefore I know that no external force can
compel you to break a promise. But that does not mean that
you yourself don't have the power to break it! And no one-not
even you-can possibly know whether you will choose to do
this in the future.
Victim: But I won't choose to do this! I know I won't.
Existentialist: But how do you know?
Victim: I don't know how I know, I just know!
Existentialist: Really now, that remark is hardly worthy of
you! How can you say that you know but that you don't know
how you know?
Victim: It is true. I do know, but I don't know how I know.
Existentialist: That is ridiculous! You don't know.
Victim: I do know!
Existentialist: You don't!
Victim: I do!
Existentialist: You don't!
Etc., etc.
Scene 2
Several months later the victim fell into the hands of an evil
brain surgeon. This surgeon was a diabolical character whose
specialty was to perform brain operations whose express purpose
was to make people choose to break their promises. And
so the evil brain surgeon operated on our victim, and as a
result the victim decided (?) to break his promise. Shortly after,
he had the following conversation with a determinist.
Determinist: So! You broke your promise!
Victim: Oh yes!
Determinist: What would you say now to the existentialist?
I know about your entire conversation!
Victim: Obviously I must admit that the existentialist was
right and I was wrong. He claimed there was a possibility that
I would choose to break my promise; I claimed there wasn't. So
clearly he was right and I was wrong.
Determinist: I would not put it quite that way. You were
wrong, of course. But I would not say he was right. He was
wrong too.
Victim: What do you mean?
Determinist: He was right in that it was not a certainty that
you would keep your promise-this you now realize. But he
was wrong in saying that it was up to you whether or not you
kept your promise. His basic fallacy is that he believes in free
will.
Victim: That's no fallacy! I also believe in free will.
Determinist: You mean you used to believe in free will.
Victim: No, I still believe in free will.
Determinist: Even after your experience with the brain
surgeon? Even after he forced you to break your promise?
Victim: I was not forced to break my promise; I chose to
break my promise.
Determinist: You really mean to say that you actually
believe that it was your choice in the matter rather than the
surgery which caused you to break your promise?
Victim: or course it was my choice!
Determinist: You sound quite proud of the fact!
Victim: Hardly! How could anyone in his right mind be
proud of breaking a promise?
Determinist: Well then, let me ask you: Why did you break
your promise?
Victim: Why did I? Because I realized that it was the best
thing I could do, that's why?
Determinist: But do you believe it is morally right to break
a promise?
Victim: Of course not! But in this case, my keeping the
promise would have been even worse than breaking it. I thus
had to choose the lesser of two wrongs.
Determinist: I don't understand you.
Victim: Look, when I originally made the promise, I did so
in good faith. I honestly believed it was best for all concerned.
But shortly after my brain operation, I started to review all
relevant facts, and I soon discovered some of the more crucial
ones I had failed to take into consideration. After having taken
them into consideration, I then realized that the promise was
not a good one-I don't mean not good for me personally, but
not good for everyone as a whole. In other words, I now realize
that keeping the promise would have been even more unethical
than breaking it-despite the fact that I fully grant that it is
always unethical to break a promise. B~t unfortunately, in life
the choice is not always between the ethical and the unethical,
but sometimes between the more unethical and the less unethical.
Whenever someone makes an unethical promise, he is
always confronted with this horrible choice. If he breaks his
promise, he is committing the unethical fact of breaking a
promise; if he keeps his promise, he may, for other reasons, be
acting even more unethically. This was my situation. I had no
choice but to break my promise.
Determinist: You sure as hell had no choice! The brain
surgeon saw to that!
Victim: No, no; I mean I had a choice, and I chose to do the
best thing under the circumstances.
Determinist: Now whom do you think you are kidding?
Look how you rationalize and flounder! Next, I suppose, you'll
be telling me that the brain operation had nothing to do with
your so-called "choice:'
Victim: No, I'm not saying that. It is quite possible that the
brain operation set in motion various thoughts concerning the
desirability of keeping my promise. Had I not had these
thoughts, I would indeed have kept my promise. But the brain
operation did not force me to break my promise; I broke it of
my own accord. I chose to break my promise.
Determinist: And I say that that is a complete and utter
rationalization! Of course the brain operation caused you to
break your promise! If you had not had the brain operation,
you would have kept your promise, but since you did have the
operation, you broke it. It is as simple as that! If event X is
followed by event Y, and if Y would not have occurred had X
not occurred, how can you intelligently deny that X was the
cause of Y? What other meaning of "cause" is there?
Victim: I disagree! It is inconceivable to me that I did not
break my promise of my own free will. When I make a promise,
there is no power in the universe-other than my own will-which
can cause me to break it.