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WHAT CONSCIOUSNESS DOES A ROBOT N
John McCarthy
Computer Science Department
Stanford [email protected]
http://www-formal.stanford.edu/jmc/
July 12, 2002
Almost all of my papers are on the web page. Thi
is http://www-formal.stanford.edu/consciousness
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APPROACHES TO ARTIFICIAL INTELLIGE
biologicalHumans are intelligent; imitate huma
observe and imitate at either the psychological or
physiological level
engineeringThe world presents problems to inte
Study information and action available in the wor
1. Write programs using non-logical representatio2. represent facts about the world in logic and
what to do by logical inference
We aim at human level AI, and the key phenom
the common sense informatic situation.
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A LOGICAL ROAD TO HUMAN LEVEL A
Use Drosophilas that illustrate aspects of repr
tion and reasoning problems.
Concepts, context, circumscription, counterfa
consciousness, creativity, approximation
narrative, projection, planning
mental situation calculus
domain dependent control of reasoning
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Logic in AI
Features of the logic approach to AI.
Represent information by sentences in a logical lan
e.g. first order logic, second order logic, modal lo
theory in logic.
Auxiliary information in tables, programs, states,
described by logical sentences.
Inference is logical inferencededuction suppleme
some form of nonmonotonic inference, e.g. circution.
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Action takes place when the system infers that itdo the action.
Observation of the environment results in sentememory.
Situation calculus formalizes the relationsholds(p, s), occurs(e, s) and the function result(e, shas a new situation as its value.
Formalizing consciousness involves giving situationtal components.
Self-observation results in sentences about the s
state of mind.
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What Introspection do Robots Need?
Whats this?: What ability to observe its own
tational state and computational processes does
need to do its tasks?
General Knowledge?: What general informationreasoning processes does it need to plan its ment
Design approach: Asking what consciousness is
gives different answers from those trying to defi
sciouness has given.
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Recommendation for AI: Introspection is needed to
whether to think or look, to learn from near mis
use counterfactuals and keep pedigrees of beliefs.
Recommendation for psychologists and philosophe
this direct design stance approach to your metho
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What is Consciousness? We consider several kin
knowledge.
There are many unconscious stimulus-respo
relations in animal and humans, and there can machines.
Unconscious knowledge can affect behavio
Conscious knowledge and other conscious infor
can be observed by the actor.
Self-conscious knowledge is conscious knowle
about conscious information.
Some aspects of behavior require decisions o
whole system. Which way to run is an example. decisions are made by a central mechanism
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In logical robots, the consciousness is be a sub-
of memory containing facts and other mental en
Reasoning involves the entities in consciousne
leads to decisions when the reasoning leads t
statement that an action should be performe
The capacity of consciousness is limited, so
information displaces old, which may go to a histo
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Taxonomy of Consciousness
The consciousness itself can be observed and thevations enter consciousness.
Robot consciousness can be given powers peopl
have.
complete memory of the past
larger immediate memory
avoiding wishful thinking
ability to self-simulate
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greater ability than humans at organizing expe
Most required features of robot consciousnesscorrespond to features of human consciousne
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FEATURES OF FORMALIZED CONTEXT
Ist(c, p), V alue(c, exp)
c : p
C(SherlockHolmes) : Detective(Holmes)
entering and leaving contexts
introspection by transcending outermost cont
Assuming(c, p)
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C(I , N o w)
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What Tasks Require Self-Consciousness?
Tasks NOT requiring consciousness
Reacting directly to the environment.
Learning direct reactions to the environment.
Tasks requiring consciousness
Anticipating the future.
Analyzing the past. Self-criticism.
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Speech requires introspection. Would this phrase
this object if I were in his place?
Mechanisms of consciousness operate
unconsciously.
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More Tasks Requiring Consciousness
Observe physical body.
. . . : c(Here, N ow, I) : hungry in(pen, hand)
Do I know that proposition?
c(Now,I) : know(sitting(Clinton))
Do I know what thing is? What is it?
c(N o w , I , ) : know-what
c(Now,I) : is(,jdoe)
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c(S-Symp, I) : is(,jdoe)
Did I ever do action? When and precisely what?
What are my goals?
What is currently happening?
What is the state of the actions I am currently pe
ing?
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What are my intentions?
c(Now,I) : intend()
What does my belief in p depend on?
What are my choices for action?
c(Now,I) : can(lecture) can(walk-out)
Can I achieve possible-goal?
Does my mental state up to now have property p
How can I plan my thinking on this problem?
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Yet more Introspection
Since I do not intend to call him again, Ill forget h
phone numberor put it in low priority storage. Pa
a proposition with a reason.
I know how to do A and dont know how to do B
Renting a cellular telephone is a new idea for me.
I tried that, and it didnt work. This isnt just bac
ing.
What would I do if I were she?
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Understanding
The meaning of understanding is context dep
To understand something is to have the fac
reasoning methods about it that are relevant
context.
People who understand cars know about crank
Fish do not understand swimming, e.g. the
ponder how to swim better.
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Comenicis coach understood womens gymna
but not from having done it.
Understanding is an approximate concept.
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Inferring Non-knowledge
Inferring non-knowledge requires special logic
treatment.
According to Godels theorem, the consistency of a
system cannot be a theorem of the system.
Inferring that any proposition is unknown implies t
tem is consistent, because if the system is inconsis
sentences are theorems.
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Godels notion of relative consistency permits pr
non-knowledge. Assume that the theory is con
and express this as a second order formula assert
existence of functions and predicates with the pos
properties. To show non-knowledge of a propo
prove that if predicates and functions exist satisfy
original theory, show that they still exist when th
added to the theory.
Second order logic is the natural toolrememberi
the proof of consistency must be accomplished
robots normal reasoning apparatus.
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Not knowing Clinton is sitting
Theory with predicates including sits
A(P1, . . . , P n, sits)
(P1, . . . , P n sits
)A(P1, . . . , P n, sits
)
expresses consistency of the theory, and
(P1, . . . , P n sits
)(A(P1, . . . , P n, sits
) sits(Clinton, s))
expresses the consistency of the theory with the
assertion that Clinton is not sitting in the situat
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Then
(8) (9)
asserts relative consistency.
(P2P3)A(P1, P
2, sits
) sits(Clinton, s).
asserts it with P1 fixed. If sits doesnt appear elsethe simplest case, we get by with
sits = (x ss)((x = Clinton ss = s) sits(x,
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Ad hoc context c(prob) for a problem prob
The c(prob) consists mainly of a theory includin
deemed relevant to prob.
c(prob) is initially empty.
c(prob is referred to from the context c0 in wh
problem is posed by lifting relations
If c(problem) is small enough, whether the pro
solvable in the context is definite and decidea
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Second order logic instead of model theory ke
cisions about.whether there is enough informa
solve the problem within the logical language.
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Relevant Work Some non-real time work is relevarobot examining its mental processes in real ti
Rationalize skillBratko, Michie, Muggleton et. a
Sternberg.
Inductive learning systematizes and generalizes fa
predicate logic.Muggleton
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Chemistry and Logic
The interaction of chemistry and logic in humans
is something we dont need in robots.
Here are some aspects of it.
When a paranoid takes his medicine, he no longer b
the CIA is following him and influencing his thoug
radio waves. When he stops taking the medicine
lieves it again.
Both the medicine and the substance to which
antagonist are too simple to encode beliefs abo
CIA.
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Hormones analogous to neurostransmitters open s
gates to admit whole classes of beliefs into conscio
They are analogs of similar substances and gates
mals.
It would seem that such mechanisms wont be u
robots.
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Philosophical and Psychological Remarks
The strong design stance has advantages for philo
Gives adequacy criteria. Will the mechanism w
Forces a greater concreteness than is custom
Shows weaknesses of a priori reasoning.
Relative consistency evades mathematical diffic
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