The Modern Intellectual Tradition

What is philosophy? One definition is that it is the most comprehensive type of inquiry, where inquiry here is the attempt to say what is true, and why i.e. justifying why it is true with evidence. Some questions that fall under philosophy include "What is health?" or "What is a cause?".

This course focuses on epistemology (theory of knowledge) and metaphysics (theory of reality), and covers the great (Western) philosophers - note here great does not always mean right.

The aim is to see the forest, i.e. the main claims of the philosophers and its opposite, since to understand something one also needs to understand its opposite.

• Epistemological realism, anti-realism/relativism, skepticism
• Questions that fall under philosophy: Does all knowledge come from sense experience?
• Philosophy roughly divided into 3 camps: analytic (started by Frege), continental (started by Husserl and Heidegger), American pragmaticism (started Charles Sanders Peirce).

Scholasticism had wide influence in Medieval Europe. It is based on Aristotle's logic and metapysics - which can be understood by the following question: "What is in the room you are in right now?". The point is that there are relationships between things, and activities done by things, in addition to just things. The primary category of "being" (primary substance) is given to things like tables, chairs etc, and other categories are properties of or predicated of those basic things. For e.g. a dog has more being than its posture, colour which are properties/activities done by the dog. Formally, a substance contains parts, but is not part of anything, properties are predicated of it but it is not predicated of anything e.g. we say "The tree is tall" instead of "Tallness is instantianted in the tree". In the end, this means the entity is independently existing.

In this metaphysics, every substance must have 4 causes:

• The material: That out of which is made of
• The efficient: The source of the objects principle of change/stability
• The formal: The essence of the object
• The final: The end/goal of the object

For Aristotle, living things have a soul - here by soul they mean the animating principle i.e. what makes something alive. There are 3 levels of soul:

• Vegetative soul, characteristic of plants which is responsible for metabolism, growth, nutrition etc.
• Animal soul, characteristic of animal life which allows for desires, moving around etc.
• Human soul, characteristic of humans, which is rational and allows for abstract thought etc.

These form a hierarchy where each higher level soul contains the lower level souls.

This metaphysics is combined with the Ptolemaic geocentric model of the universe which is a closed finite system, the Earth is at the center, the moon is the closest super-Earthly object. Everything on Earth is made of a combination of the 4 elements air, water, earth and fire meanwhile everything outside the Earth was thought to be made of a much more refined substance called Ether.

Now to come to scholasticism, which can be summarized as the combination of Aristotle's metaphysics and Christianity. Some problems arise for e.g. Aristotle's theories do not include an immortal soul.

This scholastic view was mainly challenged by the discovery of the new world, the Protestant reformation among other things. The scientific revolution also contributed since it was a challenge to Aristotle's ideas. Copurnicus challenged the view that the Earth is at the center, meanwhile Bruno challenged the view that the universe is finite. Galileo on the other hand develops a new theory of mechanics which drops references to "final causes", based on uniform motion and rest being equal, i.e. the explanation of the motion of a body does not depend on its nature or what kind of this it is, rather it depends on its mass, shape etc.

This new science (which is more mathematical) is more reminiscent to Plato's view of the world, where he believes the world is made intelligible by reference to the ideal forms which are the true realities and lie behind what we see, which is in contrast to Aristotle who believes the physical substance we interact with is the true reality.

Descartes wanted to answer the question: "What can we know with certainty?". For this he sought a new foundation of absolutely certain knowledge on which to base everything else on.

For e.g. everything learnt from the senses are put under doubtful. General facts could also be doubted since one could be dreaming. For things mathematical facts, it is possible there is an all powerful demon deceving you, meaning such facts should also be doubted.

From this, he comes to "I think therefore I exist", which Decartes reasons to be certain because the ideas in this thesis are perfectly clear and distinct, and can be seen by the natual light of reason like 1=1. It must be that a person who doubts must have a mind, and from this follows that this person must exist. This "I" is a mental non-physical thinking substance (res cogistans). From this also follows that one cannot doubt that they are thinking of something.

He also comes to the criterion of "spatial extension" for material things, which he still doubts to exist. To prove that the matter exists, he first proves that God exists. This starts from the claim that the cause of a thing is atleast as great as its effect otherwise something comes from nothing. He then says that "I have in my mind the idea of God". Now one can ask how did this idea come into this mind. Suppose it came from experience, but everything from experience is finite/imperfect. But how could anything finite/imperfect lead to the idea of something infinite/perfect? On the other hand, the mind could not have created (caused) the idea of God since the mind is finite/imperfect. The only option left is that this idea was placed in the mind when the mind was created, and could only be caused by God, which hence must exist to put the idea into one's mind. Descarte's theory for material substances arise from this to exclude the case of God being a deceiver. Overall these theories result in the separation of the mind (where emotions and free will lies) and material substances whose essence is to occupy space.

Descarte also made a novel claim that individual consciousness (field of evidence presented to ones individual mind) is the foundation for all evidence of one claim.

Later on people noticed circular reasoning, where assuming causes to be atleast greater than their effects leads to the proof of the existence of God while this leads to the belief in the natural light of reason. Also, if anything that exists is material or mind, then Descarte must classify all animals other than humans as material, i.e. they do not have feelings since otherwise it would have a mental substance which is equal to soul for Descartes due to his Christian beliefs. This also replaces Aristotle's notion of soul.

The biggest problem he leaves us with is "How does the mind and body interact?".

John Locke's most important contributions include the Second Treatise of Government and Letter concerning Toleration, however this lecture focuses on his work on epistemology, An essay cocnerning Human Understanding.

For Locke, the mind is an empty slate (tabula rasa) on which experience writes.