Re: [asa] Trees don't lie

From: Glenn Morton <glennmorton@entouch.net>
Date: Mon Mar 23 2009 - 20:57:01 EDT

I think one of the things that makes expert guesses, even with physics so
ineffectual is the observation (of someone whose quotation I can't find
right now), that one can't predict the trajectory of a ball in a
gravitational field unless you can predict what life will do. A batter hits
the ball, and you can predict the trajectory up until the point at which a
hand in a glove attached to a living being catches it and changes the
trajectory.

Any system which has life in it, is hugely unpredictable.
----- Original Message -----
From: "George Murphy" <GMURPHY10@neo.rr.com>
To: "Glenn Morton" <glennmorton@entouch.net>
Cc: "asa" <asa@calvin.edu>
Sent: Monday, March 23, 2009 8:51 AM
Subject: Re: [asa] Trees don't lie

> Glenn -
>
> Very quickly, & as far as I have anything to contribute winding this up
> for now -
>
> It's necessary distinguish between two things. (a) The basic dynamics of
> a complex system which, to the extent we can model it mathematically,
> require nonlinear equations, and (b) the analysis of some important data
> about the system which may use various math approximations. Think of the
> difference between Newton's laws and Kepler's. Many (though not all)
> nonlinear systems display sensitivity to initial conditions so that we
> can't predict the future state (i.e. the precise values of positions &
> velocities for mechanical systems) far into the future. But we can
> analyze data using various approximations and assumptions in order to
> estimate certain important facts about the future bahavior of the system.
> The latter seems to me to be what Hubbert did quite successfully.
>
> (BTW, it's easy from the math at the site I gave to see why the peak
> occurs at the point where half the initial reserve has been exhausted - in
> this approximation of course.)
>
> About the other systems (elections, MLB) I didn't say I "wanted"
> equations. I said earlier that I don't think we can have a complete math
> description of such things. But to the extent we do, or can use a math
> metaphor, they're nonlinear. & there are knowledgeable people who can
> make predictions that are not perfect but are pretty good statistically.
> They don't do that by solving equations though. I agree with Plato that
> God is a mathematician but he has other interests as well!
>
> 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 10:56 PM
> Subject: Re: [asa] Trees don't lie
>
>
>> Hi George,
>>
>>> 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.
>> .
>> I will absolutely grant that you know more math than I. But, Hubbert's
>> equation works and it is linear. The situation in oil production is
>> complex only because of political decisions made by country leaders to
>> restrict production or open the taps. Hubbert predicted a world peak oil
>> in 1995. The only reason that that prediction didn't happen was because
>> in the late 1970s and early 1980s, the world became incredibly more
>> energy efficient due to the high prices of oil. But all that did was
>> push the peak back about 10-15 years. I think we have peaked because of
>> the current down turn. We will never catch up again with the decline
>> because we are not drilling as much now. we were barely keeping up with
>> production when we were drilling all out. Now that we aren't, world oil
>> supply, defined as the amount of oil coming to market per day will
>> decline rather quickly. Buckle your belts.
>>
>>>
>>> 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.
>>
>> I didn't say that the presidential election was linear.
>>
>>>
>>> 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.
>>>
>>
>> George, those are the kinds of systems that Tetlock studied--those
>> lacking the kinds of equations you seem to want. That is why experts
>> aren't any good.
>

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Received on Mon Mar 23 20:57:01 2009

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