ilya_prigogine_isabelle_stengers_alvin_tofflerbookfi-org

75 THE IDENTIFICATION OF THE REAL
Laplaces Demon
Extrapolations from the dynamic description discussed above
have a symbol-the demon imagined by Laplace, capable at
any given instant of observing the position and velocity of
each mass that forms part of the universe and of inferring its
evolution, both toward the past and toward the future. Of
course, no one has ever dreamed that a physicist might one
day benefit from the knowledge possessed by Laplace's demon.
Laplace himself only used this fiction to demonstrate the
extent of our ignorance and the need for a statistical description
of certain processes. The problematics of Laplace's demon
are not related to the question of whether a deterministic
prediction of the course of events is actually possible, but
whether it is possible in principle, de jure. This possibility
seems to be implied in mechanistic description, with its
characteristic duality based on dynamic law and initial conditions.
Indeed, the fact that a dynamic system is governed by a
deterministic law, even though in practice our ignorance of the
initial state precludes any possibility of deterministic predictions,
allows the "objective truth" of the system as it would be
seen by Laplace's demon to be distinguished from empirical
limitations due to our ignorance. In the context of classical
dynamics, a deterministic description may be unattainable in
practice; nevertheless, it stands as a limit that defines a series
of increasingly accurate descriptions.
It is precisely the consistency of this duality formed by dynamic
law and initial conditions that is challenged in the revival
of classical mechanics, which we will describe in Chapter
IX. We shall see that the motion may become so complex, the
trajectories so varied, that no observation, whatever its precision,
can lead us to the determination of the exact initial conditions.
But at that point the duality on which classical mechanics
was constructed breaks down. We can predict only the average
behavior of bundles of trajectories.
Modern science was born out of the breakdown of the animistic
alliance with nature. Man seemed to possess a place in
the Aristotelian world as both a living and a knowing creature.