Brent Meeker writes:
> Such definitions of "causality" seem to miss the point that
> every event has mulitple causes and constraints and that
> any one of them is neither necessary nor sufficient.  As
> commonly used "the cause" is something(s) we consider could
> have been otherwise.  Heavy rains may be rare and so it is
> easy to suppose their absence.  In that case we would say
> heavy rains caused the flooding.  But if you lived where
> heavy rains were the rule, you'd more likely say something
> like, "The flooding was caused by insufficient foresight in
> providing drainage."

Yes, in this case probably the better statement would be "heavy rains
with insufficient drainage cause flooding".  Things can have more than
one cause.  In practice the difficulty seems to be to distinguish the
irrelevant from the relevant aspects.

I think what is necessary is to go from the specific and concrete
events to an abstraction which represents an entire category of events.
In any given instance of flooding, everything contributes in a sense.
If a particular stone were located somewhere else, the details of
the flooding would be different.  But if we look at flooding as an
abstraction, then we can identify other aspects which are associated
with the set of events that the abstraction covers.

You still have the problem of distinguishing correlation from causation,
but at least this allows you to identify possible causative factors.
And in general there will be more than one.

> Some physicists (Hartle, Penrose, Gell-Mann) regard quantum
> mechanics as defining an arrow of time more basic than the
> statistical increase of entropy.  This QM AoT is defined by
> the decoherence or 'collapse of the wave function'.  I
> suppose the splitting of MW would be the same. However,
> Bohm's QM is deterministic and doesn't have this QM AoT
> even though it gives the same predictions as
> non-relativistic QM. 

I believe the Huw Price book I mentioned argued that this arrow of
time is not really fundamental, but rather is due to the low entropy
of the initial conditions.  Particularly if you look at it from the
MWI perspective, in equilibrium there will be as many merges of worlds
(or "branches") as splits.

Regarding causality and consciousness:
> I don't see how a concept of causality can solve this
> conundrum.  The 'computation' can be causal and yet so
> simple that the mapping still does all the work.

Well, the mapping problem is independent of the causality issue.
Both problems have to be solved in some way.  Most people dismiss the
mapping issue by assuming that one can simply rule out mappings that are
"too complex".  I don't think it is that easy.  But even if you did have
a way of solving this, you still have the issue of replays versus truly
causal systems.  You still have to deal with the fact that causality
seems to play a role in defining what is real.

> I think
> the answer lies in embedding computation within an
> environment.  The reason the mapping can apparently do all
> the work is because it is all at a symbolic level.  If you
> imagine building a robot, the the 'brain' of the robot must
> do computation taking information from sensors and
> producing signals to actuators. Then it seems the question
> of whether the robot has done a computation has operational
> meaning and the conundrum doesn't arise. 

I've seen similar suggestions but they never make sense to me.  Can't we
provide a simulated brain with a simulated environment?  A similar thing
was done in the movie The Matrix, except in that case real brains were
put into a simulated environment.  Imagine something like The Matrix
but with computer simulations of human brains.  Then you have brain[s]
plus environment all running in a featureless gray box of a computer.
You still have to answer the question of whether the computer has minds
in it or not, so you still need to make a mapping.  I don't see that
introducing an environment has helped at all to solve the problem.

Hal Finney

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