Re: virus: Logic

David McFadzean (
Thu, 09 Oct 1997 10:42:06 -0600

At 09:52 AM 10/6/97 -0600, David McFadzean wrote:

>I have a few ideas, but I'd like to hear from others first.

As promised, here are a few ideas on logic:

Contrary to popular belief, logical arguments do not prove
a conclusion. Rather they prove a conditional: if all the
assumptions are true, then the conclusion must be true.
(Formally, if the conjunction of all premises is true, then
the consequent is true.) It is a subtle, but all-important

Every premise in an argument is just shorthand for another
argument which is, as just mentioned, a conditional. A premise
is a consequent with a hidden antecedent. It would be impractical
in the extreme (if not impossible) to make all assumptions
explicit in an argument, so we have to get by with just listing
the most controversial premises. If someone disagrees with a
premise, then the argument's advocate can backtrack and present
a new argument with the premise in question as the conclusion
(and so on).

Logical reasoning will always yield true conditionals if it
is done correctly. True conditionals can be[1] immensely
powerful models of reality. You can use them to explain the
past and predict the future. You can use them to decide what
to do now in order to create the future you want.

People justify bad decisions (or, more often, rationalize)
every day based on logic. Certainly logic can be abused, but
that doesn't make it less useful. The problem is that

True premises are not inaccessible. Everyone that has beliefs
has some true beliefs. We can only know whether any given
premise is true by examining whether it is consistent
(non-contradictory) with everything else we believe to be true.
Truth is not really binary, but can often be treated as if
it was with little loss.

And now the argument about why logic is universally applicable
to everyday living...

Every living person has values[2]. Maybe they are born with them,
maybe they got them from their parents or TV or the back of a
comic book, it doesn't matter (for the purposes of this argument).
Some states of the world manifest these values to a greater extent
than other possible states of world. Everyone prefers states of
the world that manifest their values to a greater extent (by
the definition of "values"). If people want to make choices that
would increase the probability of future states of the world
manifesting their values to a greater extent, then they should
ensure that those choices do not contradict true conditionals
to the best of their knowledge. Of course they don't *have* to
do this, they could base their choices on emotion or instinct,
and often this works just fine. They could also choose their
actions randomly, and it is possible that the choices would be
good ones. That isn't the point. The point is to increase the
probability of the choices being good ones.

So to sum up: If you are going to gamble it is worthwhile
to learn the odds. Oh, and BTW, life is a series of gambles.[3]

[1] Some true conditionals are worthless. e.g. If you live on
Mars and work on Earth then you have a very long commute. True,
but so what? It is true in logic that a false premise implies
anything, and anything implies a true conclusion. This is true
because (A -> B) -> (~A or B) -> ~(A and ~B) on a truth
functional basis. It is not clear (to me at least) that these
kinds of true conditional have any use.

[2] I think every living organism has values, but that extrapolation
is irrelevant to this argument.

[3] Level-3 disclaimer: This is just a point of view I think
subscribers might find useful. I don't believe any of it is true
but I mean everything I say. Use at your own risk. Your mileage
may vary. Do not taunt happy funball. :-)

David McFadzean       
Memetic Engineer      
Church of Virus