Tuesday, September 1, 2009

New comment on Stochastic vs. Limited Senses.

The following comment sent last semester to 471 folks is relevant given the short philosophical discusson yesterday on this topic.


ps: The full thread is available at  http://cse471-s09.blogspot.com/2009/01/stochastic-vs-limited-senses.html
---------- Forwarded message ----------
From: Subbarao Kambhampati <noreply-comment@blogger.com>
Date: Tue, Jan 27, 2009 at 7:42 PM
Subject: [cse471/598 Intro to AI Spring 2009 Blog] New comment on Stochastic vs. Limited Senses.

Jason Majors asks:

Tuesday, January 27, 2009

Stochastic vs. Limited Senses

While reading through the book today, I came up with a question. Where's the line between a lack of good senses and a stochastic environment? The examples we've had in class of what makes an environment stochastic (e.g. car trouble with the taxi) could be monitored with an appropriately advanced sensor array. An omniscient agent (or omniscient objective observer) would consider every environment fully deterministic.
So is there a clear line between the two? I would think that something that is beyond practical (such as monitoring the surfaces of a taxi's tires to know when it will weaken enough to burst from the pressure) would be in the stochastic column, but what about not knowing that a tire is going flat, because the taxi lacks a tire pressure monitoring system (which is practical)?


Subbarao Kambhampati has left a new comment on your post "Stochastic vs. Limited Senses":

This is a good question. When we do not have complete models of a world, then what is inherently a "deterministic world" may well look like a non-deterministic/stochastic one to the agent.

About the only "natural" world that can be said to be inherently stochastic is again the quantum world. In every other case, you can--if you prefer--think that the underlying world is deterministic and we just didn't model it adequately. [Even in the quantum case, many scientists--Einstein in particular--fought tooth and nail to convince the scientific community that the uncertainty is *not* inherent and that we get it only because we are not modeling the system completely. See the celebrated EPR paradox--and how it was eventually shown that the "paradox" is really not a paradox and quantum uncertainty is very much inherent: http://en.wikipedia.org/wiki/EPR_paradox ]

Notice that the "completeness" we are talking about doesn't have to involve as high a granularity as "modeling the imperfections on the coin surface and the eddies in the room air to predict the coin toss outcome".

Remember that our ancestors, not too long ago, assumed that many phenomena that we now know as deterministic--such as eclipses-- are actually non-deterministic (and thus would associate with them superstitions like "the eclipse shows the gods being angry with the ruler"--as in Chinese belief of "Mandate from the Heaven" etc).


ps: Of course, we humans are also equally adept at introducing determinism where there is none (e.g. my favorite god created this whole darned entire universe and all its life forms over a weekend some 6000 years ago....

Check out http://www.tv.com/the-simpsons/lisa-the-skeptic/episode/1471/summary.html

where Lisa laments that the expected answer to every question on her science test was "God made it" ;-)

Posted by Subbarao Kambhampati to cse471/598 Intro to AI Spring 2009 Blog at January 27, 2009 6:42 PM

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