Does discussion on this list ever cover actual control system modeling such as PID control, etc.?
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On Wed, Apr 2, 2008 at 8:00 AM, CSGNET automatic digest system LISTSERV@listserv.uiuc.edu wrote:
There are 3 messages totalling 132 lines in this issue.
Topics of the day:
- Uncertainty (was second-order and third-order beliefs) (3)
Date: Tue, 1 Apr 2008 13:43:04 -0700
From: Richard Marken rsmarken@GMAIL.COM
Subject: Re: Uncertainty (was second-order and third-order beliefs)
[From Rick Marken (2008.04.01.1345)]
Bill Powers (2008.03.31.2013 MDT)–
I conclude that we mean different things by “uncertainty.”.
Maybe. Could someone remind me why this “uncertainty” thing came up in
the first place.
I see several candidates for definitions of uncertainty about a perception:
- The perception itself seems to vary randomly so there is no way to
predict its next value.
- The perception is itself relatively constant, but is masked by random
noise which makes it hard to perceive at all, or to perceive in a consistent
way.
- The perception is ambiguous, in that parts of its lower-level components
are missing so they could be filled in by imagination in different ways,
each leading to a different familiar perception.
I see all of these as being consistent with what I mean by
uncertainty, which is a state that can exist only when a person has
the purpose of making an inference, prediction or decision about a
possible state of affairs based on a perception that is assumed to be
evidence regarding that state of affairs. In your example 1 there is
uncertainty if a person has the purpose of predicting the next value
of the perception based on the present value, where the present value
is taken to be evidence of what might happen next. In your example 2
there is uncertainty if a person has the purpose of perceiving the
perception that is masked based on a perception of the masked
perception, where the masked perception is taken to be evidence of
what perception is masked. Same for example 3, where there is
uncertainty if the person has the purpose of perceiving the complete
perception that about which the ambiguous perception is assumed to be
evidence.
I guess I’m saying that I don’t think it makes sense to talk about
perceptions themselves as being uncertain. Perceptions are just
perceptions. They become “unpredictable”, “masked” or “ambiguous” only
when there is the purpose to use those perceptions as evidence of
something else (the thing to be predicted, detected or identified).
Best
Rick
–
Richard S. Marken PhD
Date: Tue, 1 Apr 2008 19:44:38 -0600
From: Bill Powers powers_w@FRONTIER.NET
Subject: Re: Uncertainty (was second-order and third-order beliefs)
[From Bill Powers (2008.03.31.1932 MDT)]
Rick Marken (2008.04.01.1345) –
I guess I’m saying that I don’t think it makes sense to talk about
perceptions themselves as being uncertain. Perceptions are just
perceptions. They become “unpredictable”, “masked” or “ambiguous” only
when there is the purpose to use those perceptions as evidence of
something else (the thing to be predicted, detected or identified).
I basically agree with you, but I’m trying to make the whole
discussion depend less on “how we think of it” and more on stateable
principles. You can define uncertainty as an objective state of
affairs if that’s what you want to do, like Heisenberg saying that
position and momentum themselves are uncertain, independently of the
observer. That’s a proposition, and it can be discussed and argued
about, but not by saying we don’t like it or believe it. You propose
another definition of uncertainty. Is it a better one? Of course you
think it is, but why should anyone else think it is?
I think we’re trying to define a term, not really look at a
phenomenon. Either we’ll agree on a definition or we won’t. At the
moment it doesn’t matter to me, because I don’t use the idea of
uncertainty in my work very much, except when talking about things
like prediction errors, which fits in with your proposed definition.
I don’t think Martin will accept it, but we’ll see. I’m not inclined
to shut Martin off by dismissing his interests, but if they’re too
far from mine, I’m willing for us to go our separate ways on this
subject. It would be nice to get some kind of convergence, though.
Best,
Bill P.
Date: Wed, 2 Apr 2008 00:21:31 -0400
From: Martin Taylor mmt-csg@MMTAYLOR.NET
Subject: Re: Uncertainty (was second-order and third-order beliefs)
[Martin Taylor 2008.04.02]
[From Bill Powers (2008.03.31.1932 MDT)]
Rick Marken (2008.04.01.1345) –
I guess I’m saying that I don’t think it makes sense to talk about
perceptions themselves as being uncertain. Perceptions are just
perceptions. They become “unpredictable”, “masked” or “ambiguous” only
when there is the purpose to use those perceptions as evidence of
something else (the thing to be predicted, detected or identified).
I basically agree with you, but I’m trying to make the whole
discussion depend less on “how we think of it” and more on stateable
principles.
I sent out a long message on this on Monday, but it hasn’t shown up.
I’m going to send it again, despite the likelihood that you will see
it twice.
Martin
End of CSGNET Digest - 1 Apr 2008 to 2 Apr 2008 (#2008-74)