Reply to Ludwig
 
Kirk Ludwig has responded to may paper ``Why classical mechanics
cannot accomodated consciousness but quantum mechanics can''
with an article entitled:
 
>WHY THE DIFFERENCE BETWEEN QUANTUM AND
>CLASSICAL PHYSICS IS IRRELEVANT
>TO THE MIND/BODY PROBLEM
 
The focal point of his article is his set of four propositions:
 
>(1)  Some objects have mental properties.
>(2)  The fundamental constituents of objects (i.e., the objects
>     to be listed in the catalog of particle physics) do not have
>     mental properties.
>(3)  Mental properties are not conceptually or definitionally
>     reducible to non-mental properties.
>(4)  Every feature of every object is deducible from a complete
>     description of it in terms of its fundamental constituents
>     and their properties and relations.
>
>The problem is that from (2)-(4) we can deduce the negation of
>(1).  That is the mind/body problem.  (The consciousness/body
>problem is the mind/body problem restricted to mental properties
>the possession of which entail that their possessor is conscious
>or potentially conscious.)
 
Propositions (2) and (4) refer to "fundamental constituents".
 
The essential difference between quantum mechanics and classical
mechanics is that the fundamental constituents in classical mechanics
are "objects", but the fundamental constituents in quantum mechanics
are the "wave function" (i.e., the state vector) and the "events".
The wave function represents not "objects", but "propensities for events
to occur", and the basic realities are these "events" themselves.
 
This fundamental difference between classical mechanics and quantum
mechanics undermines Ludwig's discussion of the motivation for
proposition (2):
 
>To motivate (2), we need only the following two assumptions.
>The first is that no basically new sorts of entities have come into
>existence since the Big Bang--i.e., the list of fundamental physical
>particles has not changed since the Big Bang, or, at least, no new
>sorts of particles have appeared which cannot be characterized in
>terms of the same family of properties which we draw on in describing
>those originally present.<1>  The second is that at some time in the
>past no objects had mental properties.
 
Quantum events have presumably been occurring ever since the big bang,
and these events are presumably fundamentally the same as those complex
events in human brains that are the conscious experiences that we know.
Of course, human brains are endowed with a short-term memory that
injects a special kind of informational content into these brain events
that would not be present in primordial events, which, accordingly, would
not have a comparable feel.
 
Regarding motivations Ludwig asserts that:
 
>But none of these motivations
>depend on the features of physical theory that distinguish classical
>from quantum mechanics.  Thus, we should be skeptical of any claim
>that a solution to our problem is to be found by focusing on such
>differences.
 
But we see that the motivation for proposition (2) is completely upset
by the switch from classical mechanics to quantum mechanics, because
the fundamental constituents of quantum objects are events and
propensities for events, not other objects, and events can more
naturally be experiential in character than objects.
 
Later on Ludwig says:
 
>3.1  Any solution to the mind/body problem must reject one of the
>assumptions that generate it.  Our first question is whether the
>difference Stapp points to between classical and quantum
>mechanics shows that if one accepts one or the other of these
>theories one must reject one or another of the assumptions that
>generate the problem.  The answer is 'no' because the difference
>Stapp points to, as he acknowledges, is purely a logical one.
>The difference hinges on whether the vectors in the basic
>description of a physical system contain information only about
>points or also contain information about the whole system.
>Nothing about that difference bears on whether any of the
>elements in the vectors entail that the system has mental
>properties, or that it does not.  So this difference between
>classical and quantum mechanics makes no difference with respect
>to propositions (1) and (2).
 
It is clear from  this passage that  Ludwig is focussing  narrowly
upon a point that I strongly emphasized, namely the difference in
the  informational content of the quantum and classical  states,
without paying any attention to the shift from  object-based to
event-based  ontology that I  stressed  above. But it is events that
give significance  to the  informational  character of the quantum
states, in the context of the mind/brain problem.
 
What do events do? They select and actualize quantum states.
 
So, on the one hand, the events make "selections" that are not
determined by the mechanical (i.e., localizable) aspects of quantum
dynamics. This makes them natural candidates for thoughts. For as
William James concluded from a study of "the particulars of the
distribution of consciousness" (as contrasted with our perhaps
fallible intuition),
"consciousness is at all times primarily a selecting agency".
 
On the other hand, the high-level informational content of the quantum
state gives it the same sort of informational content as a thought:
it captures as a whole a nonlocal information structure. This
characteristic of events reinforces the idea that events are fundamentally
different from anything that appears in classical mechanics, and are
basically thoughtlike in character.
 
The point of my paper was to emphasize that classical mechanics provides
no such natural candidate for the experiential aspect of nature. For,
in classical mechanics the fundamental constituents are localizable
mechanically generated properties, whereas in quantum mechanics the
fundamental constituents are selections that are not mechanically
determined, and that are expressed as actualizations of nonlocalizable
information structures.
 
In his discussion of possible uses of quantum mechanics in approaching
the mind/body problem Ludwig dismisses as unworthy of consideration the
possibility that nature has dual aspects, even though quantum mechanics
is essentially dualistic, as I emphasized, having both a matter-like
aspect represented by the local-deterministic evolution of the
Heisenberg-picture local operators, and a non-matter-like nonlocal
dynamics for the evolution of the Heisenberg-picture state. It is only
these two very different---but intertwined---aspects together that allow
quantum theory to become related to human experience.
 
Henry Stapp <hpstapp.lbl.gov>