Chapter 13: Minds and Machines
- biological mechanism: on the one hand: people are machines
- biological mechanism
- heart's a pump
- arteries are hoses
- the elbow is a lever
- psychological mechanism: the brain's a computer
- advent of computers: on the other hand computers doing
intelligent things previously reserved for humans
- Descartes: held that all human physiological
functions are mechanical
- even such psychological functions as we share with the animals
-- the "passions" -- are mechanical
- but not the higher, distinctively human, intellectual functions
-- reason, or intelligence
- intelligence being an infinite capacity, Descartes reasoned
- and mechanical means being merely finite devices,
- no mechanical means could possibly produce intelligence,
- it takes an immaterial soul
- consciousness = intelligence = soul
- Technical developments
- 1642: Pascal's calculator: added and subtracted
- Refined by Leibniz (1646-1716) to multiply and divide
- Suppose that there be a machine,
the structure of which produces thinking, feeling, and
perceiving; imagine this machine enlarged but preserving the same
proportions, so that you
could enter it as if it were a mill. This being supposed, you might
visit its inside; but what
would you observe there? Nothing but parts which push and move each
other, and never anything
that could explain perception. This explanation must therefore be
sought in the simple
substance, not in the composite, that is, in the machine (Leibniz,
- Jacquard loom: 1st programmable
- Inspired Babbage (1792-1871) to design his analytical engine
- a would-have been universal device
- Lady Loveless (Augusta Ada Loveless) wrote programs for
- Boolean algebra -- using just 1s & 0s for representation and
inference -- developed by Boole (1833)
- 1930s Claude Shannon developed modern theory of information based
on Boolean algebra. Each on/off (1/0) was a unit of information
he called a "binary digit" or "bit"
- Turing described how to build "universal" machines which
- being programmable:
could prove anything strictly provable
- being expandable: would be capable of computations of unlimited
- modern digital computers are realizations of Turing's
theoretical devices & limited only by their storage capacities
- from primitive relay switches
- to vacuum tubes
- to transistors
- to increasingly integrated circuit chips
- Good old fashioned AI (GOFAI): rule-and-symbol AI:
- serial processing: computations done one at a time, one after
- Computational theory of mind: "the brain is a digital computer
and the conscious mind is a computer program" (Searle 1997: 9) [note
this is not Searle's own view: the context is critical of this view]
Developments in Computing
- Parallel processing: computations done many at a time
- more brainlike architecture:
- brains have many neurons
(brain-cells) richly interconnected (by dendrites) interactions across synapses (Fig. 13.2: 186) acting in
- similarly connection machines have many simple processors
richly interconnected (by wires) acting in parallel -- hence they are
called "artificial neural networks" (ANNs) or "neural nets"
- representations in these networks is distributed and
- these networks are not programmed but "trained"
- Underlying idea: "mind can be created only by interacting in real
time with a real environment" (Blackmore 189)
- Intelligence emerges in
the interaction of machine and environment.
Intelligence Without Representation
- Rodney Brooks -- roboticist extraordinaire: puts embodied
cognition into practice
- his robots don't build internal maps or encode descriptions of
their worlds (the GOFAI way)
- his robots "let the world itself serve as its own model"
(Brooks 1991: 396)
- "Is is only the observer of the Creature who imputes a central
representation or central control. The Creature itself has none;
it is a collection of competing behaviors."
- Limits of the embodied approach: dealing with anything high-level
- "Nouvelle AI" is weakest where GOFAI is strongest ... and vice
The Turing Test
- "I propose to consider the question 'Can machines think?'"
- Proposed an experimental test for AI (a version of Descartes'
language test) based on "the imitation game"
- if the can pass conversationally pass for human
- then it should be judged intelligent
- a qualifying test only: "the odds are weighted too heavily
against the machine"
- Turing's two predictions
- "in about fifty years' time it will be possible to program
computers ... to play the imitation game so well that an average
interrogator will not have more than a 70 percent chance of making the
right identification after five minutes of questioning" [down in
- "at the end of the century the use of words and general
educated opinion will have altered so much that one will be able to
speak of machines thinking without expecting to be contradicted"
[gloriously fulfilled in practice]
- Will computers ever pass this test?
- Would passing this test really be a decisive test of
- What about consciousness?