Epistemology

Introducing Epistemology

What is Epistemology?

  • Epistemology is the study of knowledge, truth, & justified belief

    • tries to answer What is knowledge? How do we know what we know?

  • How we obtain knowledge is the central problem in epistemology

Approaches to knowledge

  • rationalism = some human knowledge is gained ‘a priori’ (prior to experience; justification of a belief comes from pure thought or reason)

  • Empiricism: knowledge is gained ‘a posteriori’ (reasoning/knowledge comes after our observations & perceptions)

  • Innate Knowledge = The human mind is born w/ ideas or knowledge

Innate Knowledge (Plato)

  • According to Plato, what we see in the physical world is not real representations because they change

    • Thus, this type of knowledge is unreliable because people never generate more than an opinion about objects belonging to the sensory world

    • Believed humans are born w/ innate knowledge about the forms, but we have to be taught how to access that knowledge w/ the help of a philosopher

    • E.g. of Innate ideas = Love, Mother, Father

Empiricism (Aristotle, Locke, Hume)

  • argues that knowledge came from experience

    • experience was evidence through the senses

      • Believed that reason came into play after people experienced things through their senses (a posteriori)

      • Eg you see a black swan and this experience changes your knowledge of swans

Rationalism (Descartes, Kent)

  • Rationalists emphasize the importance of a priori knowledge

  • A priori knowledge is true and cannot be doubted

    • ex. mathematical ideas

Plato’s Theory of Knowledge - Justified True Belief

  • Plato and his contemporaries were not only concerned with gaining knowledge, but with being certain that it was really valid

  • Inn order to claim to have knowledge, 4 conditions needed to be met: Truth, Belief, Justification, Verifiable justification

  • Ex. “I know that ____” - this statement can only be used if:

    • 1. The statement is true

    • 2. You believe that the statement is true

    • 3. You are justified in believing that the statement is true

    • 4. Your justification doesn’t depend on a false statement

Truth

  • a) Truth is the same for everyone - what’s true for one is true for all

  • b) Truth is independent of anyone’s belief - something can be true even if everyone believes otherwise

  • c) Truth is eternal - something that is true now will be true forever

  • According to Plato’s JTB, if a statement isn’t objectively true then it can’t be certain knowledge (it would be opinion)

Belief

  • You need to believe in a statement to call it true

Justification

  • You must have good reasons to believe the validity of a statement

  • There are four main systems that allow for this:

    • 1. Logic

    • 2. Empirical Evidence (observations) - relies on perception, which can be fooled

    • 3. Memory (generally reliable, but can be wrong)

    • 4. Authority (again, toss up b/w trustful vs distrustful authorities)

Ideas vs Phenomena

  • He felt that objects of our sense experience are not entirely real because they change and whatever property an object has (cold, hot) can be interpreted differenty

  • Therefore, sensory properties are not reliable indicators of real things

  • The truly real things we come to know are not of the physical world

Rationalism and Empiricism

Rationalism

  • The first rationalists in Western Philosophy were Socrates and Plato

  • Modern Rationalism is usually associated with the mathematical methods of Descartes, Leibniz, and Spinoza

Empiricism

  • Early Greek Empiricists include the Pre-Socratics (e. Heraclitus, Pythagoras) and Aristotle

  • Modern Empiricism is usually associated with the methodology of scientific inquiry, which became known as the scientific method

  • The modern thinkers connected to Empiricism are Bacon, Locke, Hume and Hobbes

Sources of Knowledge

  • Rationalism:

    • A priori knowledge

    • Knowledge does NOT come from the senses

    • knowledge comes from reason, or from intuition, or innately

  • Empiricism:

    • A posteriori knowledge

    • knowledge comes primarily or solely from the senses

    • experience leads to the growth of knowledge

Role of Innate Ideas

  • Rationalism: tend to think that some ideas, ex. God, are innate

  • Empiricism: hold that all ideas come from experience

Methods of Acquiring Knowledge

  • Rationalism:

    • stress deduction which involves inferring from first principles

    • make conclusions based on information we already have

    • moves from specific to general

  • Empiricism:

    • stress induction which involves generalizing from observables

    • make conclusions based on observations

    • moves from general to specific

Aristotle’s Theory of Knowledge

  • Like Plato, Aristotle believed the universe is ordered and that knowledge of the world is possible (unlike the Sophists)

  • Didn’t believe that reason alone could lead us to knowledge

  • He wondered how thinking and learning about trees or animals or other people could lead us to true knowledge

  • believed knowledge gained through our senses in the repeated experience of our lives leads to knowledge of particular things and general universal concepts

  • For Aristotle and other empiricists, the answer to the questions about the acquisition of knowledge and certainty is obtained through the sensory perceptions of our experiences

  • Knowledge is a posteriori (“what comes after”)

Rene Descartes

Rene Descartes (1596-1650)

  • Didn’t believe we can rely solely on our senses for search of truth - senses can be tricked

  • We can only be certain of one thing; that we exists - “I think therefore I am” (Cogito ergo sum)

  • All other truths are based on mental perception

  • The mind is essential, what we experience is secondary

  • Detached reasoning was the route to the truth

  • Argued that God could not be observed, but could be proven to exist through reason

  • Our knowledge is innate (already in us) or deduced by rational means (ex. mathematics)

Method of Doubt

  • Practicing Catholic

  • Worried about the ability of religion to survive the challenge of science

  • Skepticism was becoming popular again - “There is no truth”

  • In order to build a philosophy based on absolute certitude, Descartes had to doubt all he was able to doubt until he was able to arrive at a truth he could not doubt

  • In order to determine this, he puts forward two methods of doubt:

    • i) he decided to examine his foundational beliefs - ex. whether he could trust his senses, mathematical ideas, etc.

    • ii) if there is even the slightest possibility of a belief being false, he will reject the belief as a candidate for knowledge

  • Descartes used the most extreme form of skepticism to find a foundation for all knowledge

  • By systematically doubting everything, he believes he has found something that he cannot doubt — that he exists

Descartes’ First Meditation

  • I can’t trust my senses

    • I could be crazy

    • I could be dreaming

    • A malicious demon could be out to fool me

Descartes’ Evil Demon Hypothesis

  • The reason that things seem to be the way that they are is because there is an evil demon deceiving you and manipulating your mind every second

  • He is making you think about certain shapes, colors and sounds and none of your senses are verifiable

Descartes’ Second Meditation

  • Is there anything I can’t doubt?

  • I can’t doubt that: I doubt

  • Doing it makes it so

  • So, “I doubt” is absolutely certain

Descartes’ Certainty (argument)

  • I doubt

  • I think

  • I exist

  • Cogito, Ergo sum. I think therefore I am

Cogito, Ergo sum

  • He concludes that he cannot doubt that he doubts

  • Skepticism is defeated, according to Descartes

  • No matter how many skeptical challenges are raised, there is at least one fragment of genuine human knowledge: my perfect certainty of my own existence

  • From this, it is possible to achieve indisputable knowledge of many other propositions

  • The undeniable fact of his existence was discerned through reason alone

  • From this foundation, Descartes built a series of propositions statements to make up his theory of knowledge that he believed explains the core questions of knowledge:

    • What can we know?

    • How do we obtain knowledge?

    • How certain can we be in our knowledge?

  • For Descartes, we can only be certain of knowledge obtained through our reason

Descartes’ Proof of God’s Existence

  • 1. A being that doubts is an imperfect being

  • 2. I doubt; therefore I am an imperfect being

  • 3. Yet I could know that I am imperfect only by having the concept of perfection

  • 4. Therefore, I do have the concept of perfection

  • 5. I could not have received the concept of perfection from something imperfect; therefore, my concept was not derived from myself

  • 6. Therefore, my concept of perfection was derived from something that is perfect

  • 7. Only God is perfect (i.e. God is perfection), so I derived my concept of perfection from him

  • 8. Therefore, God exists

  • If God exists, I am not possessed by an evil demon, and my senses can be trusted

    • God would not let an evil demon mess with me

John Locke - Theory of Knowledge

  • Rejected Descartes’ rationalist ideas

  • Believed we gain knowledge by experience (empiricism)

  • The only way we learn is by tasting, smelling, touching and hearing the external world

  • Agreed with Aristotle that we are not born with innate ideas, and that we learn through experience

  • He argues that at birth the mind is like a blank slate, or "tabula rasa” waiting to be written on by the world of experience

Two Sources of Knowledge: Sensation and Reflection

  • Sensation: sense experience from our 5 senses (ex. we see the color red, hear the piano)

  • Reflection: the mind’s process of thinking, comparing, and combining different ideas in a number of ways to produce knowledge

  • All ideas originate with either:

    • Sensation: the perception of stimuli through the senses

    • Reflection: the mind’s experience of thinking about what you experienced (processing the information)

Two Types of Ideas: Simple and Complex

  • Simple ideas:

    • 1. The most basic of knowledge (ex. yellow, hot, soft, sweet)

    • 2. Presented to us via sensation and reflection

    • 3. Once the mind experiences simple ideas, it has the power to store up. to repeat, and to combine them

  • Complex ideas: a grouping of simple ideas

    • Ex. when you look at a banana, you see it is yellow (color), it is mushy (texture) and these ideas form the complex idea of a banana

All Material Things Have Primary and Secondary Qualities

  • Primary: are inseparable from the thing that is perceived: size shape, motion, rest, height and weight (these are undeniable truths)

  • Secondary: come from the act of perception and may vary under observation: color, temperature, smell, taste and sounds

From Sense Experience to Ideas:

  • 1) Sense experience: You touch ice

  • 2) Sensation: Cold

  • 3) Impression in the Mind: Ice is cold

  • 4) Reflection: Ice = cold

  • 5) Idea: If you touch ice, it will be cold

Kant’s Transcendental Idealism - Theory of Knowledge

  • Believed that knowledge was achieved through experience and reason

  • Innate ideas alone are not knowledge

  • Experiences alone are not knowledge

  • He combines experience and reason to create knowledge

  • He says our mind shapes how we understand our experiences

Two Worlds: Noumenal and Phenomenal

  • Noumenal World: reality as it exists independent of our mind

    • Ex. the true color of a flower

  • Phenomenal World: Appearances - reality as our mind makes sense of it

    • Ex. the color of the flower as we see it vs. how a dog would see it

    • Everything we know of the external world via our senses is filtered through our mind

  • Therefore, since our mind filters knowledge of the external world, we can’t truly know reality (noumena)

Structures of the Mind

  • The mind processes sensory data through a matrix and categorizes the information

  • This creates our version of reality

  • So, our knowledge of the world is based on HOW our mind process our sense data

  • Implication: Everyone sees reality differently because of our brain’s unique matrix

How the Mind Makes Sense of the World

  • a) Sensory Experience: our senses experience the world and send information to our mind

  • b) Innate Ideas: The mind uses innate ideas to organize/structure experiences for us to gain knowledge

  • c) Space and Time: everything we perceive is first filtered through the lens of ‘space’ and ‘time’. These concepts are innate

  • d) Categories of Understanding

    • Then the matrix of the mind uses 12 concepts/categories to further process the sensory information we receives — these concepts are also innate

    • 1) Quantity - distinguish single things from many

    • 2) Quality - distinguish real and unreal

    • 3) Relation - understand an object’s properties and its relationships to other objects

    • 4) Modality - is something possible or not, exists or doesn’t