physical symbol system hypothesis

1. Physical Symbol System
• INTRODUCTION
• HYPOTHESIS
Submitted by :
Nida Quazi

2. Contents
 Physical symbol system (introduction)
 Statement
 Basic idea
 Philosophical roots
 Examples of PSS
 Contribution of Newell & Simon
 Attacks on P.S.S.

3. Physical Symbol System
 Also known as Formal system.
 It Physical Patterns
(Symbols)
Structures
(Expressions)
New
Expression

4. Hypothesis
 This hypothesis has a great position in philosophy of
Artificial Intelligence.
 Formulated by -
Allen Newell & Herbert A. Simon .
 They proposed that "symbol manipulation" is the
essence of both human and machine intelligence ; which
mean that human thinking is symbol processing.

5. “
”
A physical symbol system has the
necessary and sufficient means of
general intelligent action .
Statement of Hypothesis
“Symbolic behavior of man arises because he has the
characteristics of a physical symbol system .”

6.  This is a very strong claim as it implies both that :
human thinking is a kind of symbol manipulation (because a
symbol system is necessary for intelligence)
and
machines can be intelligent (because a symbol system is
sufficient for intelligence) .

7. Basic idea
 Symbol are physical patterns.
 Symbols can be combined to form complex symbol
structures.
 The system contains processes for manipulating
complex symbol structures.
 The process for representing complex symbol
structures can themselves be symbolically represented
within the system.

8. Philosophical roots
 Idea has roots in:
1. Hobbes : claimed reasoning is "nothing more than reckoning".
2. Leibniz : attempted to create a logical calculus of all human
ideas.
3. Hume : thought perception could be reduced to atomic
impressions.
4. Kant : analyzed all experience as controlled by formal rules.
 Latest version is called computational theory of mind - Hillary
Putnam & Jerry Fodor.

9. Examples of PSS
Formal logic or
Algebra
Digital
computer
Chess

10. SHAKEY ROBOT

11. NAVLAB

12. STANLEY

13. Appropriate & less appropriate
 Hypothesis is a core part of A.I. :
Appropriate for higher level intelligence such as chess
playing
but
less appropriate for commonplace intelligence such as
vision.

14. Contribution of Newell & Simon
 Contributed in :
1. Information processing language (1956)
2. Two of the earlies A.I. program :
I. Logic Theory Machine (1956)
II. General Problem Solver(1957)
 They were awarded ACM's A.M. Turing Award in
1957.

15. I. Logic Theorist
 A computer program written in 1955-56 ; called the first A.I.
program.
 By Newell, Simon & Cliff Shaw(computer programmer).
 First computer program to mimic problem solving skills of a
human being.
 Eventually prove 38 of the first 52 theorems, chapter 2,
Whitehead & Russell's Principia Mathematica and found new
and more elegant proofs for some.

16. L.T.'s influence on A.I.
 L .T. introduced several concepts that would be
central to A.I. research such as :
1. Reasoning as search
2. Heuristics
3. List processing

17. II. General Problem Solver
 Computer program created in 1957.
 Was intended to work as universal problem solver.
 It was the first computer program which separated its
Knowledge of problem (rules represented as input
data) from its strategy of how to solve problem (a
generic solver engine).

19.  G.P.S. focus on the available operations, finding what
input were acceptable and what output were generated. It
starts with symbolic descriptions of the start state and the
goal state.
 It then creates subgoals to get closer and closer to the
goals, i.e. aims to find a sequence of admissible
transformations that will transform the state into the goal
state.

20. Applicability of G.P.S.
1. Proofs in predicate logic
2. Euclidean geometry problems

21. Attacks on P.S.S.
1. Focuses on the presumption that computers can only manipulate
meaningless symbols.
2. Focuses on presumption that much that underlies intelligent action,
especially perception, involves non symbolic processing.
3. Claim that “computation” as it is ordinarily understood , does not
provide an appropriate model for intelligence.
4. Based on observation that much that appears to be intelligent
behavior is really “mindless”.

22. THANK YOU