Biology Reference
In-Depth Information
inherited from Aristotle
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(384-322 BC), in trying to define what
was constant either in living or non-living things. The characteris-
tics thus identified were called specific characteristics or differ-
ences. For example, man was defined as a reasonable animal. The
specific difference of 'reasonableness' set him apart from all other
animals and at the same time defined him. All the specific charac-
teristics of a thing corresponded to its essence (or nature) and
allowed it to be defined as a species. It must be understood, how-
ever, that it was not a question of simply classifying objects as we
do today. The essence acted like an inherent active ingredient
which determined every aspect of a thing because its aim was pre-
cisely to bring about the final cause. In the case of a living being,
it guided its embryonic development and its physiology. In the case
of a physical object, it caused its motion towards its natural place.
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In this essentialist framework, knowledge was therefore the knowl-
edge of essences. Individual characteristics which are not constant
from one being to another in the same species were qualified as
accidental. For example, among humans some men are tall while
others are small, but that does not change the fact that these indi-
viduals are human in nature. However, these innumerable acciden-
tal differences, which occur in addition to specific differences, were
not able to be the subject of any kind of scientific knowledge owing
to their erratic character and because they were not part of the
nature of beings. There was therefore a qualitative difference
between the specific (the natural or essential) and the accidental:
they belonged to two separate orders of reality.
As we have seen earlier, such a difference does not exist
between a deterministic system and a probabilistic system defined
by the mathematical theory of probability. This difference assumes
an essentialist mode of thought based on notions of specificity and
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The prevailing idea of the time.
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The natural place was the place considered to correspond to the nature of the
object where it achieved the state of rest. A heavy object was thus set to move
downwards and a light object upwards.
