[FRIAM] A Question For Tomorrow

David Eric Smith desmith at santafe.edu
Thu May 2 01:55:09 EDT 2019


Hi Nick, in turn, 

> On May 1, 2019, at 5:15 AM, Nick Thompson <nickthompson at earthlink.net> wrote:
> 
> I knew I would get my ears boxed for this:

Not boxed; just conversed with.

>  
> I was in a forum with a bunch of physicists last year many of whom were wedded to the notion that nature was determined by things beyond experience that we would never know.  That's both a tautology AND an oxymoron. 
>  
> Others have met you at the high level of your response, so I will now confess that I was making a small logical point.   In the first place, “things beyond experience that we could never know” IS a tautology, right. 

I think, since those two terms are defined in terms of one another, this is safely a tautology, as you say.  (Or, I think that for now, because I don’t see problems with it from any other directions against which I would check it.)

> So, that expression is merely to say that there are things we may never know.  Ok.  That’s fine.  But when you go on to say that nature is determined by unknowable causes that’s an oxymoron.  To the extent that anything is caused, by whatever means,  it reveals its causes in its behavior.  To the extent that events are random, no cause is revealed and no cause exists. 

These claims are so loose, and the categories that appear in them so broad, that whole universes of difference can live within which instance of the category one chooses to invoke.  The laws of classical mechanics describe one instance, the laws of quantum mechanics another.  The above assertion doesn’t address the conclusions on which they explicitly disagree.

Here is an example.  I may be able, by cross-linking lots of kinds and instances of “behavior” as you call it, to assert that there are configurations of cause, and I may be able to say what spaces of possibility they inhabit.  Those are the roles that state vectors play in mechanics (classical or quantum).  Indeed, it is to summarize just such an enterprise that I say physics justifies the formalization of a notion of state.

What my physics did was construct the whole space of possible state vectors, and explain the role any particular one of them would play as cause.  It did not choose for me, which particular state in the space of the possible describes a particular instance, and it could not do so, having set up the whole space as the realm of possibilities.

From only the above, by what logic would you insist that _which_ of the states we are in is something you would have access to?  I haven’t said that anything about our big system of deductions and comparisons and Occam’s-Razor compactions of the theory gave us that.  It happens that in physics, that is the role filled by a theory of observables, measurement, and related concepts.  To report what they can about which state pertains in a particular instance.  The classical mechanics version of those concepts is one in which they are sufficient to identify the state.  The quantum mechanics version of the concepts is one in which they are not.

> Now the discussion which followed your post was so far above my head, that I wasn’t sure the extent to which it addressed the following:  To what extent do you-all think the vagaries of quantum phenomena are properly generalized to the  macro level? 

I think I would try to avoid “vagaries”, and would be wary of conversations in which I didn’t know how to put some other better word in its place.  I don’t mean this as a criticism at all; only a statement that some things I know I have to put off to another day, or do jointly with somebody else.  That’s life.

Quantum states can be superpositions.  For such states, it is, by a well-understood construction, meaningless to speak of their “having” any definite value for certain kinds of observables (which depend on what case we are talking about, but for which there is no difficulty of being specific).  Heisenberg uncertainty is a special instance of this relation as well, for which a superposition with respect to one observable happens to coincide with a specific value of a different one.  The name is unfortunate.  An infinitely extended radio wave can have an arbitrarily well-defined wavelength, and correspondingly can have exactly no specific location associated with it.  It is not that we can’t “know” the position that the “wave really has”, it is that the syntactically acceptable construct “position of the wave” doesn’t actually refer to anything in the real world.  Such is the hazard of trying to get from syntax to meaning; colorless green dreams sleep furiously.  I assume this is why the project of Montague Grammar was never tenable, though the exercise and its failure were useful and informative. 

But this is also why, when you say “I was trying to make a logical point”, I see the difference of philosophers from physicists. Logic seems to me like a syntactic exercise.  (But I am not a logician, so what I said could have been offensively ignorant.). We build logics for semantic motivations, and try to use them to systematize thinking.  But the hold they have on the world is mediated by the semantics of the referents for their tokens.  Physicists, I would say, should share the trait that they generally expect those referents to turn over routinely.

> I hear a lot of talk among social scientists to the effect that now that we have quantum theory, we can’t do psychology, which talk I take to be obscurantist blather. 

I agree.  See the earlier post about Smolin versus Aaronson.  Some people use common language to show you how smart they are; others use it to give you a tool to become smarter yourself.  We do the best we can to identify who is who, in areas we can’t referee on our own.

Eric



> Do I need to be pistol-whipped on that point, too?
>  
> Nick
>  
>  
> Nicholas S. Thompson
> Emeritus Professor of Psychology and Biology
> Clark University
> http://home.earthlink.net/~nickthompson/naturaldesigns/
>  
>  
> -----Original Message-----
> From: Friam [mailto:friam-bounces at redfish.com] On Behalf Of Eric Smith
> Sent: Tuesday, April 30, 2019 2:22 PM
> To: The Friday Morning Applied Complexity Coffee Group <friam at redfish.com>
> Subject: Re: [FRIAM] A Question For Tomorrow
>  
> > I was in a forum with a bunch of physicists last year many of whom were wedded to the notion that nature was determined by things beyond experience that we would never know.  That's both a tautology AND an oxymoron. 
>  
> I think this requires care.  Never wanting to defend the positions of people I don’t know in a conversation I wasn’t in, it would be helpful to know what topic the conversation was about, in the terms the participants applied to it.
>  
>  
> Since physics has existed as a mathematical science (let’s say, since Newton?), it has employed a notation of “state” of a system.
>  
> Also since that time, it has employed a notion of the “observable properties” (shortened to just “observables”) somehow associated with the system’s states.
>  
> In classical physics, the concept of state was identical to that of a collection of values assigned to some sufficiently complete set of observables, and which observables made up the set could be chosen without regard to which particular state they were characterizing.
>  
> aka in common language, anything inherent in the concept of a state was just the value of an observable, meaning something knowable by somebody who bothered to measure it.
>  
>  
> In quantum mechanics, physics still has notions of states and observables.
>  
> Now, however, the notion of state is _not_ coextensive with a set of values assigned to a complete (but not over-complete) set of observables, which one could declare in advance without regard to which state is being characterized.
>  
> To my view, the least important consequence of this change is that the state may not be knowable by us, even in principle, though that is the case.  (To many others, this is its most important consequence.  But the reason I shake that red cape before a herd of bulls is so that I can say…)
>  
> The important consequence of this understanding is that we have mathematical formalizations of the concept of state and of observable, and they are two different kinds of concept.  It is precisely that both can be defined, that the theory needs both to function in its complete form, and that the definitions are different, that expands our understanding of concepts of state and observable.  A state still does the main things states have always done in quantitative physical theories, and in the sense that they characterize our “attainable knowledge”, observables do what they have always done.  Before, the two jobs had been coextensive; now they are not.
>  
>  
> I assume Shakespeare wrote the “There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy” line about the same phenomenon as the thing that makes the Copernical revolution a revolution: people fight to give up importance they believed they had, or control they believed they had.  Once the fight is in the culture, there may not be that emotional motive in all the combatants; they may believe they have a logical problem with the revolution.  But how can there be a logical problem with the Copernican revolution?  It is a statement about the alignments of beliefs and facts.  Likewise the concepts of state and observable in quantum mechanics.
>  
> It feels like a Copernican revolution to me, every time physics shows that new operational understandings are required, and tries to give us new language habits in which to coordinate our minds (singly or jointly) around them, to pose the question how this was known all along in our folk language and thus can be logically analyzed with its categories.  There is only very limited reason for our folk language to furnish “a description” of the nature of the world.  It is a collection of symbols that are part of “the system of us”, which when exchanged or imagined mediate coordination of our states of mind (and yes, I know this term can be objected to from some behaviorist points of view, but it seems to require much less flexibility to use provisionally than the state of a quantum system, even though it is also much less well-understood at present).  If a collection of robot vacuum cleaners exchange little pulse sequences of infrared light to coordinate, so they don’t re-vacuum the same spot, we might anticipate that there is a limited implicit representation of the furniture of the room and its occupants in the pulse sequences, but we would not expect them to furnish a description of the robots’ engineering, or the physical world, or much else.  Human language is somewhat richer than that, but it seems to me the default assumption should be that its interpretation suffers the same fundamental hazard.  Signals exchanged as part of a system should not be expected to furnish a valid empirical description _of_ the system.
>  
> Common language is fraught with that hazard in unknown degrees and dimensions; technical language can also be fraught, but we try to build in debuggers to be better at finding the errors or gaps and doing a better-than-random job of fixing them.
>  
> The fluidity and flexibility with which the mind can take on new habits of language use, and the only-partial degree to which that cognitive capability is coupled to emotional comfort or discomfort in different habits, seems important to me in trying to understand how people argue about science.
>  
> Eric
>  
>  
>  
>  
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