Chapter 1
Plato
Anamnésis (reincarnation): Plato was a rationalist. He believed that all
knowledge stems from our reasoning capabilities. He thought that our
souls belong to a World of Forms. These forms have all knowledge. Upon
birth (or: reincarnation) all this knowledge becomes inaccessible and can
only be reached by using you reason.
Allegory of the Cave: Imagine prisoners that are tied up in a cave,
facing a wall. Behind them a great fire is burning. The prisoners can only
see shadows of things moving in front of the fire reflected on the wall. This
makes them believe that the shadows are real objects. Upon releasing the
prisoners, they will be in shock, because everything they held for real,
suddenly becomes unreal. This is Plato's proof that the senses cannot be
trusted and that all knowledge therefore can only stem from reasoning.
Meno’s slave: Plato draws four squares in the sand, creating one larger
square. He then asks the slave: how long do the sides of a square have to
be in order for the surface to be doubled (of a smaller square)? The slave
answers incorrect. Plato then draws another square by drawing diagonals
in the smaller squares. The slave suddenly realises the solution. This is
Plato's proof of the existence of the World of Forms and Anamnésis, for the
slave has been able to solve the problem without having knowledge of
geometry. By using his reason, the slave has tapped into the knowledge of
the Forms. However, would the slave have been able to solve this problem
without Plato’s guidance?
The Concept of the Triangle: The concept of a triangle is proof that
information that comes through the senses, is false. Draw a triangle. We
know (from the World of Forms) that a triangle has 180 degrees corners in
total. However, every triangle you see, will never be exactly 180 degrees
thus making it everything but a perfect triangle. The triangle you imagine
IS perfect. This means that you cannot trust your senses and only should
trust your reason. In other words: our idea of the triangle stems from a
supernatural world (of Forms)
Aristotle
Principles of scientific knowledge must be: Causative, Immediate
and True.
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, Peripatetic Axiom: Nothing is in the intellect, which was not first found
in the senses (nihil est in intellectu quod non prius fuerit in sensu).
Aristotle rejects the idea of Anamnésis and says that the mind is like a
blank slate upon birth. All knowledge that is present, is derived from the
senses.
Syllogism: Aristotle argues that to explain something, we must construct
a deductive argument (This shows that Aristotle is not a true empiricist).
We only have knowledge of something if we know the cause. For example:
- Oz is human
- Humans are mortal
- Therefore, Oz is mortal
The premises are universally true, hence the conclusion must also be true.
Without truth of the first premises, you can only draw a conclusion that is
based on subjective views.
Induction: Aristotle calls the process from which we move from the
concrete to the abstract: induction. Universal truths are derived by sensory
information. However, if:
- Oz is human
- All humans have 2 eyes
- Oz must have 2 eyes
This is not universally true. No matter how much empirical data you
collect, the conclusion will always be a generalization of the data
collected. So, be careful with induction, because it does not reveal
necessary truths (they do not have to be universal).
Aristotle’s two different realms: Aristotle believed that the earth is
heavy, immobile and placed at the centre of the universe. Aristotle
discerned two realms:
- The superlunary realm. In this realm (from the moon outwards)
everything is eternal and moves in perfect circles.
- The sublunary real. In this real (The area from the moon to the earth)
things are corruptible and are born, exist for a while then die.
Everything simply moves in a straight line, then halts (imagine a
falling piece of chalk).
Aristotle’s four causes: According to Aristotle, in order to have
knowledge of something, you must know its cause. Everything had four
causes. If you had knowledge of an object, you had knowledge of these
four causes. For example: imagine a marble statue of Gaius Julius Caesar:
- Formal cause: the shape of the object, the shape of Caesar.
- Material cause: the material it is made from, marble.
- Efficient cause: the thing that made it change, the maker.
- Final cause: the purpose that the object has, aesthetic value.
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