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From: TONH%alvey@ucl-cs.arpa
Newsgroups: net.ai
Subject: Now and Then
Message-ID: <13179@sri-arpa.UUCP>
Date: Fri, 31-Aug-84 22:53:00 EDT
Article-I.D.: sri-arpa.13179
Posted: Fri Aug 31 22:53:00 1984
Date-Received: Wed, 12-Sep-84 02:21:14 EDT
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From:  TONY HASEMER (on ALVEY at Teddington) <TONH%alvey@ucl-cs.arpa>

(Tony Hasemer challenges Norm Andrews' faith about cause and effect)

You say: "logical proof involves implication relationships between
discrete statements...causality assumes implication relationships
between discrete events".

Don't think me just another rude Brit, but:-

     > in what sense is a statement not an event
         A statement (as opposed to a record of a statement,
         which is a real-world object) takes place in the
         real world and therefore is an event in the real
         world.

     > what do you mean by "implication"
         This is the nub of all questions about cause and
         effect, and of course the word subsumes the very
         process it tries to describe.  One can say "cause
         and effect", or "implication", or "logically
         necessary", and mean ALMOST the same thing in each
         case.  They all refer to that same intangible feeling
         of certainty that a certain argument is valid or that
         event B was self-evidently caused by event A.

     > what do you mean by "relationship"
         Again, this is a word which presumes the existence
         of the very link we're trying to identify.


   May I suggest the following-

   The deductive logical syllogism (the prototype for all
infallible arguments) is of the form

     All swans are white.
     This is a swan.
     Therefore it is white.

Notice that the conclusion (3rd sentence) is only true iff the two
premises (sentences 2 and 3) are true.  And if you can make any
descriptive statement beginning "All..." then you must be talking
about a closed system.
   Mathematics, for example, is a set of logical statements about
the closed domain of numbers.  It is common, but on reflection rather
strange, to talk about "three oranges" when each orange is unique and
quite different from the rest.  It is clear that we impose number
systems on the real world, and logical statements about the square
root of the number 3 don't tell us whether or not there is a real
thing called the square root of three oranges.
   I'm saying that closed systems do not map onto the real world.
Mathematics doesn't, and nor does deductive logic (you could never
demonstrate, in practice, the truth of any statement about ALL of a
class of naturally-occurring objects).
   On the contrary, the only logic which will in any sense "prove"
statements about the real world (such as that the sun will rise tomorrow)
is INDUCTIVE logic.  Inductive logic and the principle of cause and
effect are virtually synonymous.  Inductive logic is fuzzy (deductive
logic is two-valued), and bootstraps itself into the position of
saying: "this must be true because it would be (inductively) absurd to
suppose the contrary".
   There is no real problem, no contradiction, between the principle
of cause and effect and deductive logic.  There is merely a category
mistake.  The persuasive power of deduction is very appealing, but
to try to justify an inductive argument (e.g. causality) by the
criteria of deductive arguments is like trying to describe the colour
red in a language which has no word for it.  We just have to accept that
in dealing with the real world the elegant and convenient certainties
of the deductive system do not apply.  The best logic we have is
inductive: if I kick object A and it then screams, I assume that it
screamed BECAUSE I kicked it.

   If repeated kicking of object A always produces the concomitant
screams, I have two choices: either to accept the notion of causality,
or to envisage the real world as being composed of a vast series of
arbitrary possibilities, like billions of tossed pennies which only
by pure chance have so far happened always to come down heads.  Personally,
I much prefer a fuzzy, uncertain logic to a chaos in which there is no
logic at all!  Belief in causality, like belief in God, is an act of
faith: you can't hope to PROVE it.  But whichever one chooses, it doesn't
really matter: stomachs still churn and cats still fight in the dark.
The very best solution to the problem of causality is to stop worrying
about it.

     Tony.