Biology Reference
In-Depth Information
of a phenomenon always depends on the physical and chemical con-
ditions for it to occur, and in this sense, one cannot speak of indeter-
minism here. Probability does not deny the causality of phenomena:
it just opens up to plurality the relationship between the cause and
effect, which is one-to-one in the context of determinism.
2.2.2
Probability is not incompatible
with reproducibility
Another very widespread error which must be avoided in a discus-
sion dealing with the mechanisms of embryogenesis consists in
believing that a probabilistic phenomenon is not reproducible
because it involves chance. On the contrary, the concept of proba-
bility expresses the existence of order and reproducibility where
there was thought to be none, before it was conceived.
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When
chance is rationally mastered by mathematics, predictions can be
made with a very great degree of accuracy by calculating probabil-
ity. This is commonly done nowadays in modelling numerous natu-
ral or economic processes.
We have already seen that the probability of an event is seen in
the frequency of its occurrence being stable when it is repeated a
very great number of times. To be precise, the definition of the
probability of an event X occurring is its frequency as the number
of experiments performed approaches infinity. In practice, if we
repeat an experiment involving random events a very great number
of times, each time we perform it the events occur with constant
frequency, ignoring minute negligible deviations. For example, if I
play heads or tails, the frequency of each of these events will always
be 50%. Probability thus expresses a stable structure of the world
which is not manifested by individual events but by populations of
events which are repeated a great many times. Unlike common
sense, probability expresses reproducibility where it is not immedi-
ately obvious. It indicates that the order of the world is not
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The calculation of probabilities was invented in the 17th century by Pascal to
solve problems connected with games of chance.
