Joseph Weizenbaum
SCIENCE AND THE
COMPULSIVE PROGRAMMER
There is a distinction between machines whose ultimate function
is to transduce energy or deliver power, and abstract machines , i.e. , machines
that exist only as ideas. The laws which the former embody must be a subset of
the laws that govern the real world. The laws that govern the behavior of
abstract machines are not necessarily so constrained. One may , for example,
design an abstract machine whose internal signals are propagated among its
components at speeds greater than the speed of light in clear violation of
physical law . The fact that such a machine cannot actually be built does not
prohibit the exploration of its behavior.
It
can be thought about and even
simulated on a computer. (Indeed , the Education Research Center at M.LT.
has made computer generated films that place their viewers in the position of
observers of a world in which vehicles travel at physically impossible speeds.)
The human imagination must be capable of transcending the limitations of
physical law if it is to be able
to
conceive such law at all.
The computer is , ofcourse, a physically embodied machine and, as such,
cannot violate natural law . But it is not completely characterized by its mani–
fest interaction with the real world. Electrons flow through it , its tapes move,
and its lights blink , all in strict obedience to physical law ,
to
be sure, and the
courses of its internal rivers of electrons are determined by openings and
closings of gates, again by physical events. But the game the computer plays
out is regulated by systems of ideas whose range is bounded only by the
limitations of the human imagination. The physically determined bounds , on
the electronic and mechanical events internal
to
the computer, have no
significance whatever with respect to that game, no more, that is , than it
matters how tightly a chess player grips his bishop or how rapidly he moves it
over the board .
A computer running under control of a stored program is thus detached
from the real world in the same way as is every abstract game. The chess board ,
the thirty-two chessmen, and the rules of chess constitute a world entirely
separate from every other world . So does a computer system together with its
