Re: [asa] Trees don't lie

From: George Murphy <GMURPHY10@neo.rr.com>
Date: Sun Mar 22 2009 - 22:29:08 EDT

Again you of course know a lot more about oil production than I. But when I
take a quick look at a discussion of Hubbert's math at
http://wolf.readinglitho.co.uk/subpages/hubbertmaths/hubbertmaths.html I see
a slightly wavy curve of P/Q vs Q and the phrase "Let us fit a straight line
to this set of dots from 1958 on ..." . Now I understand that Hubbert's
original analysis was more complex but what's being done here looks like
making the simplest - linear - mathematical description of what is really a
pretty complex phenomenon in order to predict, not the precise future state
of the system but one crucial feature of particular interest. I would be
very surprised if the real dynamics of oil production - if we could have a
precise mathematical description - is really describable with strictly
linear equations. If it is, please enlighten my ignorance by showing me
that it is or referring me to an appropriate source.

Similarly for the other systems I mentioned. What is the justification for
saying that the dynamics of a presidential election or a MLB season are
linear? To the extent that the term is meaningful, I suspect that the
dynamics of all complex systems involving human beings are "nonlinear." A
group of 50 Indians confronting 50 Pakistanis isn't just 50 times a 1 on 1
meeting between an Indian and a Pakistani.

In discussing elections it's significant that you put "equation" in quotes -
and never actually write down any. That's because you don't have any. You
have relationships that to some extent are semi-quantitative but you don't
have A = B relationships. & unless you do, the terms "linear" & "nonlinear"
can be used only in the loose (but I hope meaningful) way I did in the
previous paragraph. & since you don't have real equations, the concepts of
chaos theory can also be applied only in a loose way - which is not to say
that they might not be of some value if you're careful.

Shalom
George
http://home.roadrunner.com/~scitheologyglm

----- Original Message -----
From: "Glenn Morton" <glennmorton@entouch.net>
To: "George Murphy" <GMURPHY10@neo.rr.com>
Cc: "asa" <asa@calvin.edu>
Sent: Sunday, March 22, 2009 8:12 PM
Subject: Re: [asa] Trees don't lie

> Hi George, you wrote:
>
>
>
>> If it isn't too presumptuous (because you know far more about this than I
>> do), let me call attention to Hubbert's prediction in 1956 that oil
>> production in the lower 48 would peak around 1969. It did in 1970. Of
>> course that wasn't a precise prediction of the sort we can sometimes make
>> in physics but it was more than just some average guy on the street
>> saying "I think oil's going to start getting scarcer pretty soon." If
>> you wish you can fill in some details on how Hubbert made that prediction
>> but I'm guessing that it was with informed & intelligent extrapolation
>> from data about known reserves, likely finds of new fields, oil
>> consumption, &c. It wasn't by trying to solve some complicated set of
>> equations.
>
> If you look back at my qualifications on my statement, I specifically
> stated that it was nonlinear equations which were unpredictable. Of
> course a physicist will do a better job of predicting when a ball hits the
> floor than a guy off the street. In the case of Hubbert's equations, they
> are linear
>>
>> & that prediction isn't unique. Political pollsters predict results of
>> elections & often are quite accurate. Las Vegas oddsmakers make (in
>> effect) statistical predictions about the likelihood of various teams
>> winning the NCAA tournament, the world series, Super Bowl, &c. Sometimes
>> they're wrong - not much of anyone expected Tampa Bay to be in the World
>> Series or the Cardinal in the Super Bowl - but if they give 100-1 odds
>> against some team winning, you're probably throwing your money away if
>> you bet against them.
>
> I think this is going way off the mark of where Tetlock's conclusions
> apply. Every system he examines is a highly nonlinear system. So, it
> simply doesn't prove him wrong by citing lots of linear equations or
> sampling theory.
>
>> 2d, & less important for the basic question, don't overemphasize the role
>> of nonlinearity in all this. Yes, many nonlinear systems display
>> sensitivity to initial conditions but not all do. As the most obvious
>> counterexample, a damped nonlinear oscillator will come to rest
>> asymptotically, regardless of initial conditions. & while some of the
>> systems you list, & especially those involving human beings, are very
>> complex & it's in practice impossible to predict their precise state at
>> all future times, we in fact have no differential equations, linear or
>> not, that describe the dynamics of such systems. (What are the equations
>> of motion of a US presidential election?) So while speaking of these
>> systems as "nonlinear" may be a helpful metaphor it's no more than that &
>> risks giving a more reductionistic picture than is appropriate.
>
>
> I think non-linearity and systems with numerous feedback loops are
> precisely what Tetlock is talking about, so, I don't think you can simply
> claim to have disproven him by citing a lot of stuff that he doesn't talk
> about.
>
> As to the presidential election, one has a whole lot of 'equations'. If
> our enemies kidnap Americans 6 weeks before the election, the incumbent
> party gets more votes. If candidate A gaffes and comedians laugh about
> it, candidate A loses votes, If the market falls apart 6 weeks before the
> election the party in power loses votes. If the pecadillos of the
> candidate (his taste for sleeping with goats) comes out before the
> election, he loses votes. If Al Qaeda beheads some movie star, Hollywood
> switches parties. All these affect the election and they are conditional
> clauses with an equation at the heart of the conditional. If candidate B
> disagrees publicallywith the core values of their supporters, subtract X
> votes because some of the supporters are going to stay home.
> There are lots of relational equations that go into any election: if this
> then add or subtract votes.
>
> ----- Original Message -----
> From: "George Murphy" <GMURPHY10@neo.rr.com>
> To: "Glenn Morton" <glennmorton@entouch.net>
> Cc: "asa" <asa@calvin.edu>
> Sent: Sunday, March 22, 2009 12:15 PM
> Subject: Re: [asa] Trees don't lie
>
>
>> Glenn -
>>
>
>>
>> Shalom
>> George
>> http://home.roadrunner.com/~scitheologyglm
>>
>>
>> ----- Original Message -----
>> From: "Glenn Morton" <glennmorton@entouch.net>
>> To: "George Murphy" <GMURPHY10@neo.rr.com>
>> Cc: "asa" <asa@calvin.edu>
>> Sent: Saturday, March 21, 2009 10:42 PM
>> Subject: Re: [asa] Trees don't lie
>>
>>
>>>I would say that the climate, the weather, political systems,, economics,
>>>the oil markets etc, are all highly nonlinear. Tell me if it is going to
>>>be raining where you are 33 days from now. Tell me what the price of the
>>>stock market will close at on Monday. Tell me what the price of oil will
>>>be April 23. Tell me what country will be our biggest problem in 2010.
>>>All of these things involve nonlinearities.
>>>
>>> And I disagree that if one cant predict from them they won't be studied.
>>> They will be studied because they are the real equations that govern
>>> this universe and curiousity and hope that we can predict something will
>>> ensure their study
>>>
>>> ----- Original Message -----
>>> From: "George Murphy" <GMURPHY10@neo.rr.com>
>>> To: "Glenn Morton" <glennmorton@entouch.net>; "William Hamilton"
>>> <willeugenehamilton@gmail.com>; <mrb22667@kansas.net>
>>> Cc: "asa" <asa@calvin.edu>
>>> Sent: Saturday, March 21, 2009 7:34 PM
>>> Subject: Re: [asa] Trees don't lie
>>>
>>>
>>>> For a chaotic system one can't predict the future state of the system
>>>> in detail for any length of time. But you can often make (a)
>>>> statistical predictions & (b) thermodynamic predictions about the
>>>> overall state of the system. Of course these are related. If all
>>>> nonlinear dynamics could do was to say that we can't predict anything
>>>> then people wouldn't publish books &c on nonlinear dynamics.
>>>>
>>>> Shalom
>>>> George
>>>> http://home.roadrunner.com/~scitheologyglm
>>>>
>>>>
>>>> ----- Original Message -----
>>>> From: "Glenn Morton" <glennmorton@entouch.net>
>>>> To: "George Murphy" <GMURPHY10@neo.rr.com>; "William Hamilton"
>>>> <willeugenehamilton@gmail.com>; <mrb22667@kansas.net>
>>>> Cc: "asa" <asa@calvin.edu>
>>>> Sent: Saturday, March 21, 2009 3:05 PM
>>>> Subject: Re: [asa] Trees don't lie
>>>>
>>>>
>>>>> George wrote Saturday, March 21, 2009 10:11 AM
>>>>>
>>>>>> I agree that in some fields "expertise" is overrated. It's pretty
>>>>>> funny, in a gallow humors way, to hear the argument that financial
>>>>>> firms have to pay big bonuses in order to hold on to the people whose
>>>>>> "expertise" has driven the company, & maybe the country, into the
>>>>>> ground. OTOH there's a populist temptation to debunk the idea of
>>>>>> expertise because then "we're just as good as they are." & it's not
>>>>>> clear that being able to predict the future is always the best
>>>>>> criterion.
>>>>>
>>>>>
>>>>> There is no doubt that a physicist knows the equations and where it
>>>>> comes to deterministic systems, the physicist will do way better than
>>>>> anyone else. But, most systems we humans deal with are decidedly NOT
>>>>> linear or deterministic. They are non-linear. And one thing that
>>>>> should have been learned, but apparently hasn't been by many in the
>>>>> field of science, NO ONE can predict the state of a nonlinear system
>>>>> after a certain period of time. The physicist is as helpless as the
>>>>> plumber or homeless person and thus, all guesses will have the
>>>>> equivalent chance of success.
>>>>>
>>>>> that is why experts differ on what the stock market will do, what the
>>>>> weather will be like next week etc. And when it comes to global
>>>>> warming, everyone is absolutely sure that they know what this grand
>>>>> nonlinear system we call climate will do. They are acting as if it is
>>>>> a linear system when it is decidedly nonlinear.
>>>>>
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>>>
>>
>
>
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Received on Sun Mar 22 22:29:33 2009

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