Philosophy of Epistemology

From Philosophy Archive

Jump to: navigation, search
Image of the Cartesian Theatre from Wikipedia



Epistemology deals with the question about knowledge, such as: How do we know things? What can we know?

We can be mistaken about many things, through delusion and lapses of memory etc. Sceptics would say that it is not possible to know anything, some philosophers try to prove we can be certain about some things.

The arguments from illusion and deception

Optical and auditory illusions: eg. Paintings of stairs which appear to go up and down and the same time (by Escher). Delusions, waking dreams and visions: The mind can create illusions under certain circumstances (madness, fever, hunger etc.) Natural illusions: Mirages and refraction etc. Relative sensations: Eg. Warm water to a cold hand feels hot.

These are ordinary doubts, but global scepticism is the doubt of everything that we experience. Ordinary doubt (Local scepticism): Did i leave the kettle on?-Which is about facts and can be found out Philosophical doubt (Global scepticism): Is it possible to tell if the iron is on?

I can find out if the mirage deceived me, but some may say one doesn't have the ability to put such mistakes right.

Arguments against philosophical doubt

The mistakes we make through senses come through taking accuracy for granted. Philosophical doubt doesn't accept errors are part of the world: What would it be like if sticks in water did not appear to bend. Most illusions involve unfavorable conditions, and are realised when normal conditions return.

Can we know reality from a dream?

Rene Descartes asked this. Some people dream about waking up, an infinite regress where anything thought of as real is just part of the dream itself. However, you cannot have dreaming without waking up- So sometimes we must be awake. If everyone was always deceiving to you, would you know what truth was? "Man is the measure of all things" Protagoras "cogito ergo sum- I think, therefore I am" Descartes Hume- all knowledge is based on habit, not logic or neccesity

Rationalism (a priori knowledge) and Empiricism (a posteriori knowledge)

When someone burns their hand, they learn not to do it again. Has experience taught them, or by analysing the experience? Rationalism: Was championed by Descartes, Leibniz and Spinoza, and is suggested by Order: Through laws and maths we can predict things (though superposition of electrons etc. argues with this) Necessity: Truths are necessary (could not be otherwise). Eg. 2+2=4 and inside angles of a triangle add up to 180. Certainty: Descartes looked for certainties to base facts on. But how can we jump from 2+2=4 to "God exists"


Logical (necessary or analytic truths)- When something is true by definition- All bachelors are unmarried Empirical (contingent or synthetic truths - Could have happened otherwise, but didn't. What is, not what must be- Elephants are grey Metaphysical- Eg. The ontological argument. Goes beyond logical certainty, the flaw of rationalism.

Innate ideas and a priori knowledge

We are born with ideas that are innate (inborn), like maths. (as shown by the dialogue with Meno) Ideas can appear regardless of experience. Criticism of this includes: how can you distinguish learning from remembering. Most ideas rely on the real world to bring them out, eg. how can a child know the angles inside a triangle add up to 180, without knowing the name of the shape. Also, if mathematical ideas were innate, we would already know the answer to complex sums. If "God exists" is innate, why doesn't everyone believe that.

Why do we believe 2+2=4, black isn't white An idea is clear if we cannot help notice it- Eg. pain or desire An idea is distinct if cannot be confused. Eg, numbers cannot, toothache can. If distinct=distinct+clear (If distinct enough, we must notice it)


Locke and Plato thought of the mind as white paper, without any ideas.

Empiricists says some truths are independent of experience (eg. bachelors), but are not innate. Most is experienced. All ideas come from experience. Locke said there are simple ideas (redness of a rose, fire is hot, ice is cold) and complex ones formed from these eg. changes in temperature burn. Locke says we can know which perceptions are true/real through primary and secondary qualities. A table has primary qualities (eg. size, shape, speed, quantity) and also secondary qualities produced by powers which act on our senses (colour, taste, smell, temperature). We can only know primary qualities, secondary ones are subjective. Locke said there are three types of knowledge: Intuitive- This is the most difficult to doubt and are believed unquestionably- eg. "Black is not white", "I have a body" Demonstrative- when simple ideas are put together to demonstrate something. For example, the heat of the sun can be compared with the heat of a fire- they are the same. Sensitive- Just on senses

Problems with the two categories: We can only experience the two categories, not the objects themselves (Berekely).


Experiences are just in the perceiver (us), as we only see things everything could just be idealism, not matter. Powers aren't made, as they only exist in our perception. When we see a red object, it's redness is part of our perception- not the effect of some power.

Arguments he used against Locke: Sensation- When you put your hand from cold to warm water it feels hot. The perception of the temperature must be in the perceiver Taste- If a taste is pleasurable, the pleasure cannot exist in the sugar. People see different colours, but an object cannot contain different colours at once. Speed is relative If we can't imagine the perception of something then we cant say it exists.


He was a sceptical empiricist, who disagreed with innate ideas. He said there are two forks of knowledge: Relations of ideas: a priori Matters of fact: eg. The sun will rise tmw- it might not. Ideas are weaker versions of sense impression- The idea of the sun isn't as vivid as looking. Nothing in the mind can first exist without being experienced, or formed through combinations of other experience.

Causation: Hume said that all knowledge of cause and effect comes from habit. The more experienced, the more certain.

Perception and scepticism: Surrealists say "it is not a pipe!".

Theories of perception


Naive realism (Direct realism): Perceiver->Object -How do we know if it is true or false?

Representative (Indirect realism)

We experience reality indirectly by perception that represent the real world. This explains light conditions, and different positions (perspectives). Perceiver->Perception->Object Descartes, Locke and Hume believe this. If we only ever see perceptions (Locke's secondary qualities) how do we know they exist?


Perceiver-> Perception He takes Locke's theory and says through it we can't experience objects. We can touch things, see other ppl interacting +agree on what they see. Originally Berkely wrote idealism to disprove scepticism. Problems with idealism: Our perceptions are all different (don't correspond)- All different, but similar. If jon always says green as red, he might as well see green. If things seem different to different ppl at different times then there would be chaos.


This is best known as Berkel's explanation for why with representations why can't we just say they don't exist. Everything is through the senses. We dont see the object, just our experience of it. When you say "a tree" you mean a certain perception of a brown shape. Small difference, but means we say nothing of a tree- just the perception. We shouldn't think of objects as things we can't see, with substance, which then interact with our senses and give us representations of it. Phenomenalism says things don't necessarily just not exist, they exist as permanent possibilities of experience. Phenomenalists like Ayer said if statements cannot be confirmed by sense experience then they were literally non-sensical.


Naive realism- Doesnt account for illusions. Representative- Objects don't exist. Idealism- In proposing everything is immaterial has the problem out perceptions have nothing to refer to (no physical objets) and so cannot be verified.


Foundational- The car is red (From direct experience) -Not based on other beliefs. Second hand info. may rely on believing that the source is accurate, but can still be considered foundational. To test if something is true we need to question the next level , built itself from beliefs. This may continue into an infinite regress. Idealism: There are no foundational beliefs- our beliefs exist in a network of inter-related perceptions. Problems: If false beliefs out way true beliefs, we may come to a false conclusion (eg. conspiracy theories). In coherence theories all beliefs are equal and shed light on each other- but if one belief is true as it coheres with another, who do they cohere with? (Infinite regression).


Making predictions from what usually happens. (Eg. claiming to speak russian can be proved by a russian speaker) Two methods of reliable justification: External- (Reliable, eg. a doctor diagnosing me) Internal- (Unreliable, eg. relying on sensations from my internal organs) But how do we know that something that is reliable is right? A computer with a bug in it is reliably incorrect.


Ayer said a proposition is true iff an experience is verified eg. Knowing the Amazon is the longest river by satellite photos. Problems with phenomenalism: Things are verified using scientific equipment- same problems as reliabilism. Ethical and aesthetic statements, and maths and logical statements, seem to be independent of experience: Ayer said these are just conventions of language.

Verification- by its own criteria- is not an analytic truth convention of language- and it is not possible to experience it. In a correspondence theory of knowledge all beliefs are linked on an equal level.

Originally distributed on, This document can be distributed freely, so long as all the text (including this) is included.

Much summarised from content by Gareth Southwell. Many thanks to Wikipedia Epistemology page for much of this page.


Bertrand Russell

In Epistemology, Russell said we could be familiar with objects in two ways: knowledge by acquaintance (eg. meeting someone) and knowledge by description. He also thought that we could only be acquainted with our own sense data and that everything else we had to know through reasoning. Important books in the philosophy of Epistemology


Personal tools
  Popular Philosophers
Biography of Rousseau
Biography of Epictetus
Popular Branches
Philosphy of Ethics
Philosophy of Aesthetics
Philosophy of Epistemology
Philosophy of Metaphysics
Vistaprint Coupon
Zend Coupon Expedia Coupon Code
GoToMeeting Coupon
GoToMyPc Pro GotoMeeting