Oct 12 Aristotle the biologist
History of Animals
Parts of Animals
Generation of Animals
The Two Aristotles?
• Scientific method – what is it, and should we expect our
historical characters to be modern?
• The Theorizer (physics?)
• The Observer (biology?)
= False dichotomy
He used both sense experience and reasoning. Sometimes did data-collecting
(empirical evidence) to refute an old theory or support a new one.
Sometimes he “saw” what fit his preconceived ideas; finding and selecting
facts can be guided by theory, for good or bad. Example of “seeing” insect
sex in such a way that the dubious facts became support for his form-matter
explanation of reproduction. Does he follow his own stated rules: “credence
must be given to observation rather than to theory, and to theory only in so
far as it agrees with what is observed.”
Evidence of the senses? A’s theory of violent motion
(projectiles). Why didn’t they see the parabolic
motion?
Collect facts before theorizing? Known as an
empirical biologist. But often his biological facts and
theories were not well supported with facts.
Aristotle the logician
• Syllogism method of logical deduction.
• Modelled on geometric proofs – from a known general
truth to proving new specific truths. (is it really something
new or just a specific case of the already accepted?)
• Is this approach useful in scientific research?
• Classic formulation of syllogism:
All men are mortal. (true principle)
Socrates is a man. (true principle)
Therefore Socrates is mortal. (thus demonstrated)
Goals of his biology work
• Order the diversity of life.
• Medical uses.
• Empirical evidence for and/or exemplars of his doctrine of
4 causes. Animals and their parts can be explained as “for
the sake of.” (Formal, efficient, and teleological causes are
all the same = “soul” of all living things.)
Value of biological study
• “For even those animals that are not attractive to the
senses, yet to the intellect the craftsmanship of nature
provides extraordinary pleasures for those who can
recognize the causes in things.”
Aristotle’s teleology
• Study whole animal, and its “needs” for survival, for
actualizing its form.
• Explain structures in terms of functions. Each part/organ
exists for a purpose for the good of the animal.
• The final cause of each animal is its own complete state,
and nothing more. [no designer god.] A tiger is born and
grows into an adult for the sake of becoming a tiger.
Theories of generation (reproduction)
• Old debate: do both male & female contribute seed? What
is it, what is it made from? How does offspring inherit traits
from father/mother?
• Old theories: pangenesis, preformation
Aristotle’s theory: male vs female roles
• Father contributes the form to the embryo. (“active”) Does
not contribute any material. Evidence from insects and
birds – no fertilization.
• Mother contributes the material. (“passive”)
• Male is more “complete” because he has more “hot”
quality, more concocted (cooked). Hotness is the superior
condition. Female as “deformed male.”
– Fact or theory or gender bias?
– Rational reasons for believing this?
Females have less hotness; can’t fully concoct their
matter-form; don’t develop complete “human form.”
Heredity theory: taking after the father/mother
– Complete development of embryo produces the traits of
the father = actualized form.
– Less complete development produces more traits of the
mother.
– Least complete development produces a monster =
does not have human form.
Classifying species
• OBJECTIVE?
• highest to lowest ranking: criteria
• Based on type of “soul” (psyche) each group contains.
Nutritive (nutrition in plants), sensitive (sense, locomotion
in animals), rational (humans). The soul/form is dependent
on matter, so does not exist separately from it or after
death. No immortality.
• Based on amount of heat each group has. (blooded vs
bloodless; hot vs cold-blooded). Theory that the function
(telos) of the lungs in higher animals is to cool the
overheated bodies, to release heat thru breath and take in
cooler air.
• Based on how they bear young: viviparous (live), complete
eggs, incomplete eggs, asexual, spontaneous generation.
• Ranked lowest to highest forms of life on the “great chain
of being” (scale/ladder).
Scale of nature
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Man
Viviparous quadrupeds
Birds with complete eggs
Reptiles with complete eggs
Fish with incomplete eggs
Insects with incomplete eggs
Mollusks, worms by asexual reproduction
Sponges, insects by spontaneous generation from nonliving matter