The Foundations of AI
Artificial Intelligence
Mr. Sciame
Section 2
FIRST FOUNDATION
Philosophy (428 BC – Present)
• Questions for AI
1. Can formal rules be used to draw valid
conclusions?
2. How does the mental mind arise from a physical
brain?
3. Where does knowledge come from?
4. How does knowledge lead to action?
Applying Rational Thought to
Machines
• Aristotle – Formulated Logic
• Da Vinci – Designed the first calculator
• Wilhelm Schickard – 1st Calculating machine
(1623)
• Blaise Pascal – The Pascal Adder (1642) – The
more famous calculating machine; much like
an odometer on a car.
Pascal and His Adder
The Mind as a Physical System
• René Descartes (1596-1650) was first to
clearly discuss the distinction between mind
and matter.
• A physical mind leaves no room for free will.
– If the mind was governed by physical laws, it has
the free will of a rock “deciding” to fall to Earth.
Dualism
• Descartes proposed
dualism
– There is a part of the
human mind (soul or
spirit) outside of nature.
– This part was exempt
from physical laws.
– He felt animals did not
possess this dual nature
and could be treated as
machines.
Materialism
• Alternative to dualism
• The brain’s operation
according to the laws of
physics constitutes the
mind.
• Free will is the
perception of available
choices in the choice
process.
Establishing the Source of Knowledge
• Empiricism
– Nothing is in the understanding, which is not first in
the senses. – John Locke
• Induction
– General rules are acquired by exposure to repeated
associations between their elements.
• Logical Positivism
– Knowledge can be characterized by logical theories
connected to observational sentences that correspond
to sensory inputs
Connection of Knowledge to Action
• A vital question for AI, since intelligence
requires actions as well as reasoning.
• There must be an understanding of how
actions are justifiable (or rational).
Aristotle
We deliberate not about ends, but
about means.
SECOND FOUNDATION
Mathematics (800 AD – Present)
• Questions for AI
1. What are the formal rules to draw valid
conclusions?
2. What can be compared?
3. How do we reason with uncertain information?
• Three contributions
– Logic
– Computation
– Probability
The Formal Rules
• George Boole (1847)
– Boolean Logic
• Gottlob Frege (1848-1925)
– Extended Boolean logic to include objects and
relations, used today as a basic knowledge
representation system.
• Alfred Tarski (1902-1983)
– His theory showed how to relate objects in a logic
to objects in the real world.
The Limits of Logic and Computation
• Algorithms
– Step by step methods for problem solving.
• The incompleteness theorem
– Some Functions cannot be represented by algorithms.
• The Turing Machine (1936 – Alan Turing)
– You could create a machine capable of computing a
computable function
– No machine can tell in general whether a given program
will return an answer, or run forever.
Probability
• The possible outcomes
of gambling events
THIRD FOUNDATION
Economics (1776 to Present)
• Questions for AI:
1. How should we make decisions as to maximize
payoff?
2. How should we do this when others may not go
along?
3. How should we do this when the payoff may be
far into the future?
Historical
• Adam Smith (1776) – An Inquiry into the
Causes of the Wealth of Nations.
– First time Economics is treated as a science.
• The study of making choices that lead to
preferred outcomes.
• Theory updated by John von Neumann (1944)
The Theory of Games and Economic Behavior.
Decision Theory
• The Decision Theory:
– Combines Probability with Utility
– Provides a framework for decisions
– This works for large economies (it doesn’t matter
what the other guy does); smaller ones treat this
as a game (the actions of one affect others)
Payoff for the Future
• Herbert Simon (1978)
– Won the Nobel Prize
– Showed that making decisions that were “good
enough,” rather than looking for an optimal
decision, gave a better description of human
behavior.
FOURTH FOUNDATION
Neuroscience (1861 to Present)
• Questions for AI:
1. How do brains process information?
Definition
• Neuroscience is the
study of the nervous
system, and in
particular, the brain.
The Neuron
• Parts include:
– Cell Body
– Dendrites
– Axon
Comparason
Computer
Human Brain
Computational Units
1 CPU, 108 gates
1011 neurons
Storage Units
1010 bits RAM
1011 bits disk
1011 neurons
1014 synapses
Cycle Time
10-9 seconds
10-3 seconds
Bandwidth
1010 bits/second
1014 bits/second
Memory Updates/Second
109
1014
FIFTH FOUNDATION
Psychology (1879 to Present)
• Questions for AI:
1. How do humans and animals think and act?
Studies
• Behavioralism
• Cognitive Psychology
• Cognitive Science
Behaviorism
• The study of animal
behavior
• Relationship of stimuli
to responses
Cognitive Psychology
• The view of the brain as an information
processing device.
• Three steps of a knowledge based agent:
1. The stimulus must be turned into an internal
representation
2. The representation is changed by cognitive
processes into new internal representations
3. These are translated back into actions.
Cognitive Science
• Addresses the psychology of memory,
language, and logical thinking
• “A cognitive theory should be like a computer
program” (Anderson, 1980)
• AI Examples:
– Newell and Simon’s The Logical Thinking Machine
– Noah Chomsky and language
SIXTH FOUNDATION
Computer Engineering (1940 to
Present)
• Questions for AI:
1. How can we build an efficient computer?
• We discussed this in our first notes.
SEVENTH FOUNDATION
Control Theory and Cybernetics
(1948 to Present)
• Questions for AI:
1. How can artifacts operate under their own
control?
Inventions of Control Devices
• 250 BC – Water Clock
• 1600’s – Thermostat (Drebbel)
• 1800’s – Steam Engine (James Watt)
Theories
• Control Theory:
– A regulatory mechanism trying to minimize
“error” (the difference between the current state
and the goal state)
• Objective Function
– Designing systems that behave optimally.
EIGHTH FOUNDATION
Linguistics (1957 to Present)
• Questions for AI:
1. How does language relate to thought?
Books on the Subject
• Verbal Behavior – B.F. Skinner
• Syntactic Structures – Noah Chomsky
• Skinner:
– Behaviorialist Approach
• Chomsky:
– Creativity in language
• Children’s sentences.
Natural Language Processing
• Understanding Language:
– Not just sentence structure.
– Also subject matter and context