Epistemology

Normal incredulity

Doubting a claim because the available evidence is insufficient, while remaining willing to change one’s belief if new evidence appears.

Philosophical scepticism

The view that knowledge claims can be doubted even when evidence is presented, because the sceptic can question the reliability of the evidence itself.

Purpose of sceptical arguments

Sceptical arguments test the reliability of sources of knowledge such as perception, reason, and memory.

Local scepticism

A belief which raises doubt with one particular area of knowledge, It is scepticism about some specific claim, or more commonly some area/branch of supposed knowledge.

Global scepticism

The view that knowledge of any kind may be impossible, raising doubt about all knowledge claims.

Illusion (first wave of doubt)

Because our senses sometimes deceive us through illusions, we cannot be completely certain that sensory knowledge is reliable.

Dreaming (second wave of doubt)

Since dreams can feel indistinguishable from waking experience, we cannot be certain that the physical world we perceive is real.

Evil demon (third wave of doubt)

Descartes imagines a powerful deceiver who manipulates his thoughts, meaning even logic and mathematics could be false.

Cogito ergo sum

I think, therefore I am (the only piece of certain knowledge).

John Locke’s response to scepticism

Locke claims the mind gains knowledge through experience of the external world which is mind-independent.

Bertrand Russell’s response to scepticism

Russell argues we are directly aware of sense-data, which provide indirect evidence for the existence of external objects because the sense-data are produced by something.

Practical response to scepticism

Although certainty may be impossible, the best explanation of our consistent experiences is that they are caused by a real external world.

Sceptical criticism of empiricism

Sceptics argue that sense-data do not prove that external objects exist because the same experiences could occur in dreams or illusions.

Reliabilism

A subject knows that a proposition is true if and only if a subject believes that the proposition is true, the proposition is true, and the subject's belief that the proposition is true is formed by a reliable cognitive process.

Reliable cognitive process

A process which produces a higher proportion (over 50%) of true beliefs.

Criticism of reliabilism against scepticism

Reliabilism may fail to defeat scepticism because it is difficult to prove that our cognitive processes are genuinely reliable.

Intuition

The immediate understanding of a truth by the mind which does not involve reasoning or inference.

Deduction

The use of step-by-step reasoning from known truths to lead to another truth. It often uses syllogisms.

Syllogism

A type of reasoning where you start with two ideas that are true and use them to make a new, true conclusion.

Clear ideas

Ideas that are easy to understand and accessible to the mind.

Distinct ideas       

Ideas that are separate from all other ideas.

Cogito ergo sum  

I think, therefore I am

a priori knowledge  

Knowledge gained without any sense experience. You don't need to go and find anything out from the world. 

Trademark Argument

Descartes’ argument that the idea of a perfect God must be caused by a perfect being, therefore God exists.

Cause principle (Trademark Argument)

The cause of something must contain at least as much reality or perfection as its effect.

Role of God in Descartes’ epistemology

God guarantees that clear and distinct ideas are reliable and not deceptive.

Descartes’ proof of the external world

Because God is perfect and not a deceiver, our strong sensory beliefs about the external world must be true.

David Hume’s objection to the cogito

We never experience a stable self, only changing perceptions and thoughts. The self is just a bundle of changing perceptions rather than a single stable substance.

No thinker problem

The cogito may only prove that thinking occurs, not that a thinker exists.

Response to the no thinker problem

Thinking necessarily implies a thinker, so the existence of the thinker is revealed in the act of thinking.

Hume’s Fork

The division of knowledge into relations of ideas and matters of fact.

Relations of ideas

Analytic, a priori propositions that are necessarily true (e.g. logic or mathematics).

Matters of fact

Synthetic, a posteriori propositions that are contingently true and known through experience.

Response to Hume’s Fork

Rationalists argue that reason can provide genuine metaphysical knowledge, such as knowledge of God.

Cartesian Circle

The criticism that Descartes relies on clear and distinct ideas to prove God but uses God to guarantee the reliability of clear and distinct ideas.

Response to the Cartesian Circl

Clear and distinct ideas are self-evidently certain when perceived, and God later guarantees their general reliability.

Idealism

The view that the immediate objects of perception are mind-dependent ideas, and that mind-independent physical objects do not exist.

Esse est percipi

To be is to be perceived

Berkeley’s challenge to the primary/secondary quality distinction

Berkeley argues that primary qualities (shape, size, motion) vary with perspective and conditions, so they are just as mind-dependent as secondary qualities.

The Master Argument

When you try to imagine an unperceived object, you are perceiving it in your mind, so it is impossible to conceive of an object existing unperceived.

Illusion and hallucination under idealism

If all objects are mind-dependent ideas, then illusions and hallucinations are not fundamentally different from ordinary perception.

Berkeley’s response to illusion and hallucination

Ideas caused by God are involuntary, coherent, and follow natural laws, while ideas from imagination or dreams are voluntary and less consistent.

Solipsism problem for idealism

If objects only exist when perceived, it may seem that only one’s own mind exists, making the existence of other minds uncertain.

Berkeley’s response to solipsism

Objects continue to exist because they are always perceived by God, an infinite and ever-perceiving mind.

Problem of God’s perception

If sensory ideas involve sensations like colour or pain, and God cannot experience sensations, it is unclear how sensory ideas can exist in God’s mind.

Berkeley’s response about God

God understands ideas intellectually rather than experiencing them phenomenally and causes our sensory ideas according to the laws of nature.

Indirect Realism

The view that the immediate objects of perception are mind-dependent sense-data that are caused by and represent mind-independent objects.

Sense-data

The contents of perceptual experience (e.g. colour patches, shapes, sounds).

Locke’s Primary Qualities

Properties that exist in the object itself, such as shape, size, and motion.

Locke’s Secondary Qualities

Properties that exist only in the mind of the perceiver, such as colour, taste, smell, and sound.

Scepticism problem for Indirect Realism

If we are only directly aware of sense-data, then we never directly perceive physical objects and cannot be certain that mind-independent objects exist.

Locke’s argument from the involuntary nature of perception

Perceptions cannot be controlled in the way imagination can, suggesting they are caused by something external to the mind, namely mind-independent objects.

Argument from the coherence of experience

Different senses provide consistent information about the same object, suggesting an external object is causing these experiences.

External world as the best hypothesis

Belief in an external world best explains and organises our perceptual experiences, whereas denying it leads to extreme scepticism.

Berkeley’s resemblance objection

Sense-data cannot resemble mind-independent objects because mental things cannot resemble physical things, so indirect realism cannot explain how sense-data represent the external world.

Direct Realism

When you perceive the world, you perceive real, mind-independent objects directly, just as they are.

Argument from Illusion

Perceptual situations where an object appears different from how it really is (e.g. a straight pencil looks bent in water), suggesting we do not perceive objects exactly as they are.

Direct Realist response to illusion

The object has a relational property in those conditions (e.g. bent-looking in water), so the perception is still of the real object.

Argument from Perceptual Variation

The same object can appear different depending on lighting, angle, distance, or observer, suggesting perception may not reveal the object’s real properties.

Direct Realist response to perceptual variation

The object has a relational property in those conditions (e.g. lighting, angle), so the perception is still of the real object.

The argument from hallucination

You can perceive things that are not there at all and hallucinations feel the same to real perception.

Direct Realist response to hallucination

Veridical perception and hallucination are fundamentally different mental states. The fact they are indistinguishable is just a psychological limitation, not proof they are identical.

Time-Lag Argument

Because light and sound take time to reach us, we perceive objects as they were in the past, not how they are now (e.g. seeing the sun as it was 8 minutes ago).

Direct Realist response to time-lag

Causal delay does not introduce a mental intermediary, so perception can still be direct. Just because you see it as it was 8 minutes ago, doesn't mean it is not direct perception.

Plato's tripartite definition of knowledge

A subject knows that a proposition is true if and only if a subject believes that the proposition is true, the proposition is true, and the subject's belief that the proposition is true is justified. 

Individually necessary

The conditions are all needed to satisfy the conclusion.

Jointly sufficient

Together the conditions are enough to satisfy the conclusion.

Gettier Case

Smith has strong evidence (the president has told Smith that Jones will get the job) that Jones will get a job and knows (JTB (has seen them 5 minutes before the interview)) that Jones has ten coins in his pocket. From this, Smith infers: “The man who will get the job has ten coins in his pocket.” He believes this and is justified. However, Smith himself (unknown to him) has ten coins in his pocket and he gets the job. His belief is therefore true and justified, but true only by luck. So Smith has a justified true belief, but not knowledge. 

Infallibilism

A subject knows that a proposition is true if and only if a subject believes that the proposition is true, the proposition is true, and the subject's belief that the proposition is true is infallibly justified (the proposition is indubitable). 

How Infallibilism beats Gettier cases

Beats Gettier because Smith was not infallibly justified to believe that Jones will get the job. 

No False Lemmas

A subject knows that a proposition is true if and only if a subject believes that the proposition is true, the proposition is true, the subject's belief that the proposition is true is justified, the subject's belief that the proposition is true is not based on a false lemma. 

How No False Lemmas beats Gettier cases

Beats Gettier because the lemma that the president is telling the truth is false. 

Reliabilism

A subject knows that a proposition is true if and only if a subject believes that the proposition is true, the proposition is true, and the subject's belief that the proposition is true is formed by a reliable cognitive process. 

Reliable cognitive process

A process which produces a higher proportion (over 50%) of true beliefs (eg sight). 

How Reliabilism beats Gettier cases

Beats Gettier because hearing someone lie is not a reliable cognitive process

Epistemic Virtue Knowledge

A subject knows that a proposition is true if and only if a subject believes that the proposition is true, the proposition is true, and the subject's belief that the proposition is true is a result of exercising epistemic virtues.

Epistemic virtues

Particular skills, abilities or traits that contribute to someone getting to the truth. They are the processes and qualities that are more likely to yield a higher rate of true belief.

How Epistemic Virtues beat Gettier cases

Beats Gettier because Smith did not use an epistemic virtue.

Innatism

The claim that there is at least some innate knowledge, not derived from experience, but somehow part of the structure of the mind.

The slave boy argument

Socrates demonstrates that an uneducated slave can discover innate geometric truths, specifically that a square constructed on the diagonal of a 2x2 square has an area of 8, suggesting knowledge exists within the mind prior to education.

Leibniz’s view of the mind

A veined block of marble

Necessary truths

Things that are true in all possible worlds and cannot be otherwise (mathematics).

Leibniz’s Innatism

Necessary truths are universal and cannot be derived from experience, they must arise from innate rational structures within the mind.

Tabula rasa

Blank slate

Argument from Universal Consent Fails against Innatism

If ideas were innate, everyone would be aware of them but children and those with cognitive impairments are not aware of logical principles or innate ideas.

No Evidence of Innate Moral Principles

Moral rules vary between cultures. If moral truths were innate, they would be universally recognised. 

All Ideas Come from Experience

Simple ideas come from sensation (external experience) and reflection (internal mental processes). Complex ideas are built from these simple ideas.

Response to argument from universal consent fails

Innate ideas need not be consciously present. They can exist like veins in marble. 

Response to no evidence of innate moral principles

Maybe morals are not innate. Basic moral tendencies such as fairness may still be universal beneath surface differences. 

Response to all ideas come from experience

Necessary truths such as maths and logic appear to go beyond experience. Experience provides particular instances, not necessity. Necessary truths require a priori justification. 

Acquaintance knowledge

'knowing of', recognition, familiarity, direct experience. 

Ability knowledge

'knowing how', skills.

Propositional knowledge

'knowing that', knowledge of the truth or falsity of propositions. 

A necessary condition

Something which has to be true for something else to follow, but may not be enough on its own. E.g. being a man is a necessary condition of being a bachelor. 

A sufficient condition

A condition which once it is achieved, is enough for something else to follow. E.g. being an unmarried man is a sufficient condition of being a bachelor. 

Real essence

It can be given a real definition. There's a genuine difference between liquids on a molecular level that makes some liquids water and some not.

Nominal essence

No real definition possible. There is no genetic difference between weeds and non-weeds; the classification is culturally specific. 

Circularity

It must not contain the term being defined.

Obscure

The definition should not be more complicated or confusing than the original term, otherwise what's the point? 

Negative definitions

You can't define a term by what it isn't.