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From: daryl@oracorp.com (Daryl McCullough)
Subject: Re: Is Common Sense Explicit or Implicit?
Message-ID: <1994Sep21.131455.3228@oracorp.com>
Organization: Odyssey Research Associates, Inc.
Date: Wed, 21 Sep 1994 13:14:55 GMT
Lines: 136

pindor@gpu.utcc.utoronto.ca (Andrzej Pindor) writes:
(in response to DrewDalupa <drewdalupa@aol.com>)

>Why did a rock slide down a hillside? Perhaps it had a desire to lower
>its potential energy? Are you saying that "By denying yourself 
>the explanation in terms of desire, you leave yourself with that much 
>less understanding of the world around you"?

Assuming that you don't mean your question about rocks to be simply
rhetorical, I think I can explain how the explanatory value of desires
is much better for people than it is for rocks. In the case of a rock,
saying that the rock desires to lower its potential energy is no more
informative than simply describing the behavior directly (say, using
physics). In contrast, consider a statement such as "The man bought a
gun because he wanted to kill the pesky raccoon." Surely, you must
admit that this explanation in terms of desire or purpose is much
better, and more full explanation than saying: "The man bought the gun
because such and such neuron fired in this or that part of his brain..."

Using folk psychology to describe human behavior in terms of desires,
beliefs, emotions, and plans provides *enormous* explanatory and
predictive power. Of course, there are limits to folk psychology; we
can't deduce from first principles what desires a person has, or what
beliefs they hold, and perhaps a more reductionist approach would give
us a better understanding of such foundations. I don't believe that a
fuller understanding of how human brains work, even (or especially)
down to the level of atomic structure would ever supplant folk
psychological explanations.

>The claim you seem to be making is that one needs to accept objectivity of
>notions like desires (or beliefs) to understand behavior of other people.
>This would make sense if one had some reasonable way of determining what
>these beliefs or desires are.

I don't want to make such a strong claim that there is a single,
objective explanation in terms of beliefs, etc. However, neither is
there a single, objective explanation of the world in terms of
physical theories. The best we can say is that a particular theory
succeeds (at least to a certain extent) in explaining and predicting
our observations.  In the same way, we can never know for sure what
another person's beliefs, desires, etc. are, but we can try various
combinations to see what gives the best theory for describing that
person's behavior.

>In another place, referring to authorities (Freud and Wittgenstein),
>you claim that people may have purposes (desires) they are unaware of,
>which are apparent to other people. And how do these other people know
>about person's desires (he/she is unaware of)? I am sure that the only
>way is from person's behavior, is it not? Then, however, what is the
>explanatory power of these notions? Desires explain behavior, but we
>know just from behavior what the desires are! Isn't this sadly circular?

No, it is *happily* circular. Let me try on the corresponding claim
about, say, physics: 

	Some folks (Einstein, Newton, among others) claim
	that there are these "physical laws" governing the
	universe, and that if we only knew these laws, we
	could predict and understand our observations about the
	universe. But how do people know what these laws
	are? I am sure that the only way is from observations.
	Then, however, what is the explanatory power of the
	notion of "physical law"? Laws of physics explain
	observations, but we only know from observations what
	the laws are. Isn't this sadly circular?

The way in which a theory can be more than the observations
that gave rise to it is because the observations are just a list
of particulars, while a theory is a generality. The theory is
not simply a restatement of the observations, but is an attempt
to guess the pattern that underlies the observations. In a similar
way, we may use a person's behavior as a guide in guessing his
beliefs and desires, but such attributes do not simply restate
the behavior, they generalize from the behavior, and give us an
indication of how the person would behave in a new circumstance.

>Let me take an example of your shopping habits. You claim that the only way
>for me to explain this strange regularity in your behavior (going to the shop
>every seventh day) is to assume that you have a belief that there is food
>in the shop to be purchased. First of all, I do not see how this belief
>explains the regularity. Secondly, for this to be an explanation, I have
>to have some way of determining that you really have this belief, other
>than you going to the corner shop. In fact I may construct another theory:
>you fancy a young lady who works a cash register every Friday. Please tell
>me how can I find out what your belief is which would help me to predict
>your behavior (in particular if you may be unaware of it, for instance that
>you fancy this young lady).

Where is your sense of empiricism? You can either be a naturalist or
an experimentalist. If you are a naturalist, then you don't want to
actually intervene, but just observe unobtrusively. Go into the store
when Drew is there, and see if he looks longingly at the young lady
when she is not looking. See if he goes out of his way to make sure
that he goes through her checkout line (even when other lines are
shorter).  See if he smiles at her and makes an effort to say
something pleasant when he walks by. See if he seems to be buying
cheap things (a pack of gum) just so he will have an excuse to go into
the store. The hypothesis that a person is in love has *tremendous*
predictive power. If these predictions aren't largely borne out, then
it is a good bet to assume that Drew is not in love.

>Now I am sure that one can construct a robot powered by batteries, which it 
>from time to time has to recharge from an electrical outlet in the lab walls.
>Assume also that the robot memorizes the position of the outlet when it 
>wanders around the lab in its 'free' time. Now you could of course say 
>that the robot 'believes' that there is electrical current in the outlet,
>since every time its batteries are low it would go to the outlet. In case of
>robot this is not necessary, since we know well how its system works and can
>explain its behavior without invoking  the 'belief'.

I don't have any problem with the idea that a robot has
beliefs. However, the whole point of ascribing beliefs and desires is
that it provides a very compact way to both explain past behavior and
predict future behavior (in novel contexts). If the folk psychology
explanation of the behavior simply restates the behavior, then it is
not worth much.

>In case of humans we do not know workings of the brain very well, so
>we stick to the vague notion of belief. However, do we have reasons to
>think that human 'beliefs' which you invoke to explain behavior, are
>any more objective that the belief we could ascribe to the robot
>above?

As I said, I don't think that a better, or even a "complete"
understanding of the way the brain works would supplant an explanation
of behavior in terms of desires, beliefs, etc. A psychological
explanation---"The man shot the raccoon because he was angry that it
had knocked over his trash can."---is a much *better* explanation
than one that goes "The man shot the raccoon because such and such a
neuron fired..." even assuming that the second explanation is
possible. It is better because it is succinct and doesn't get bogged
down in irrelevant details.

Daryl McCullough
ORA Corp.
Ithaca, NY
