Epistemology

a posteriori

Knowledge of propositions that can only be known to be true or false through sense experience.

a priori

Knowledge of propositions that do not require (sense) experience to be known to be true or false.

ability knowledge

Knowing 'how' to do something, e.g. 'I know how to ride a bike'.

acquaintance knowledge

Knowing 'of' someone or some place. For example, 'I know the manager of the restaurant', or 'I know Oxford well'.

Cartesian circle

Refers to the circular reasoning Descartes seems to employ regarding clear and distinct ideas and God: Descartes cannot rely on clear and distinct ideas before proving God exists, but he cannot prove that God exists without relying on clear and distinct ideas.

analytic

A proposition that is true (or false) in virtue of the meanings of the words. For instance, 'a bachelor is an unmarried man' is analytically true, while 'a square has three sides' is analytically false.

cogito, the

I think', Descartes' first certain knowledge.

belief

Affirmation of, or conviction regarding, the truth of a proposition. E.g. 'I believe that the grass is green.'

copy principle, Humean

All simple ideas are copies of impressions.

direct realism

Physical objects exist independently of our minds and of our perceptions of them and the immediate objects of perception are mind-independent objects and their properties.

clear and distinct ideas

A clear idea is 'present and accessible to the attentive mind'; a distinct idea is clear and also sharply separated from other ideas so that every part of it is clear.

disjunctive theory of perception

If something looks a certain way, then one of two quite different things is going on: either I directly perceive a mind-independent physical object that is F or it appears to me just as if there is something that is F, but there is nothing that is F.

empirical

Relating to or deriving from experience, especially sense experience, but also including experimental scientific investigation.

empiricism

The theory that there can be no a priori knowledge of synthetic propositions about the world (outside my mind), i.e. all a priori knowledge is of analytic propositions, while all knowledge of synthetic propositions is gained through sense experience.

empiricism, classical

The theory that all knowledge is gained from experience: All concepts are gained from sense experience or experience of our own minds; and all knowledge of synthetic propositions about the world (outside my mind) is gained through sense experience.

external world

Everything that exists outside of our minds.

Gettier case

A situation in which we have justified true belief, but not knowledge, because the belief is only accidentally true, given the evidence that justifies it.

hallucination

A non-veridical perceptual experience that is not coherently connected with the rest of our perceptual experience.

hallucination, argument from

Against direct realism: The possibility of hallucinatory experiences that are subjectively indistinguishable from a veridical perception means that we don't immediately perceive physical objects, but sense-data.

epistemology

The study ('-ology') of knowledge ('episteme') and related concepts, including belief, justification, and certainty. It looks at the possibility and sources of knowledge.

idea, complex

An idea that is derived from two or more simple ideas.

idea, simple

A single, uniform conception, with nothing distinguishable within it.

identical, numerically

One and the same thing. Everything is numerically identical to itself, and nothing else.

identical, qualitatively

Two or more things are qualitatively identical if they share their properties in common, for example, two separate copies of the same picture.

illusion

A distortion of the senses that means that what we perceive is different from what exists.

Hume's 'fork'

We can have knowledge of just two sorts of claim: the relations between ideas and matters of fact.

indirect realism

We perceive physical objects, which exist independently of the mind, indirectly via sense-data which are caused by and represent physical objects.

idea

An object of perception, thought, or understanding. Locke uses the term to refer to a complete thought, taking the form of a proposition, e.g. 'bananas are yellow'; a sensation or sensory experience, e.g. a visual sensation of yellow; or a concept, e.g. 'yellow'.

infallibilism

To be knowledge, a belief must be certain. If we can doubt a belief, then it is not certain, and so it is not knowledge.

infinite

Without any bounds or limits. E.g. the natural numbers form an infinite series, the numbers continue in both directions (positive and negative numbers) without any end point.

innate

Knowledge or ideas that are in some way built into the structure of the mind, rather than gained from sense experience.

idealism, Berkeley's

All that exists are minds and ideas. What we think of as physical objects are, in fact, bundles of ideas. The immediate objects of perception (ordinary objects such as tables, chairs etc.) are ideas, mind-dependent objects. Esse est percipi (aut percipere) - to be is to be perceived (or to perceive).

innatism, concept

The claim that some of our concepts are innate, not derived from experience, but somehow part of the structure of the mind.

innatism, knowledge

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

intuition

Direct non-inferential awareness of abstract objects or truths.

intuition, rational

The capacity to discover the truth of a claim just by thinking about it using reason.

illusion, argument from

Against direct realism: Illusions can be 'subjectively indistinguishable' from veridical perception, (e.g. a crooked stick in water) so we see sense-data, and not physical objects, immediately.

justification

What is offered as grounds for believing an assertion.

impression

What we are immediately and directly aware of, which can either be impressions of 'sensation' or impressions of 'reflection'. Impressions of sensation derive from our senses, impressions of reflection derive from our experience of our mind, including emotions.

lemma

A claim made part way through an argument.

matters of fact

States of affairs, how the world is. According to Hume, they are known through experience and induction, especially causal inference.

mind-dependent

Depending on a mind for existence or definition, e.g. ideas are mind-dependent.

mind-independent

Not depending on a mind for existence or definition. According to realism in perception, physical objects are mind-independent; according to moral realism, moral properties are mind-independent (in some important way).

necessary condition

One proposition is a necessary condition of another when the second cannot be true while the first is false. For example, being a man is a necessary condition of being a bachelor, as if you are not a man you cannot be a bachelor.

no false lemmas

The 'no false lemmas' condition is sometimes added to the tripartite theory of knowledge and says that for something to count as knowledge it must be the case that you did not infer it from anything false.

perception, immediate objects of

What we are directly aware of in perception, which may be physical objects or sensations of these.

perceptual variation, argument from

Against direct realism: Different people perceive the same physical object differently. Therefore, what each person perceives is how the object appears to them. This appearance is mind-dependent sense-data. Physical objects are therefore not perceived directly.

physical object

Material objects, including things like tables, books, our own bodies, plants, mountains.

property, relational

A characteristic that something has only in relation to another thing. E.g. 'Pete is taller than Bob', or 'Alice loves Jack'.

rationalism

The theory that there can be a priori knowledge of synthetic propositions about the world (outside my mind) gained through rational insight and reasoning.

rationalism, classical

The theory that there can be a priori knowledge of synthetic propositions about the world (outside my mind) that is innate and then developed through rational insight and reasoning. The concepts involved in innate knowledge are also thereby innate.

relativism

The theory that some area of discourse, e.g. concerning truth, knowledge or morality, is 'relative to' a society or person. According to relativism, a proposition may be true 'for' one person but not another; or an action may be morally right in one society but not another.

reliabilism

The theory that you know that p if p is true, you believe that p, and your belief is caused by a reliable cognitive process.

represent

A relation of one thing (e.g. sense-data) to another (e.g. physical objects) established by an accurate and systematic correlation of the first to the second.

resemblance

A relation of similarity (in properties or appearance) between two things, e.g. sense-data and physical objects.

perception

Awareness of apparently external objects through use of the senses.

scepticism

The view that our usual justifications for claiming our beliefs amount to knowledge are inadequate, so we do not in fact have knowledge.

scepticism, global

Scepticism about all knowledge claims, especially concerning the existence and nature of anything outside the mind.

scepticism, local

Scepticism about some specific claim, or more commonly, about some area/branch of supposed knowledge.

sensation

Our experience of objects outside the mind, perceived through the senses.

primary quality

Properties that are 'utterly inseparable' from the object, whatever changes it goes through, even if it is divided into smaller and smaller pieces. The object has these properties 'in and of itself'. Locke lists extension (he also talks of size), shape, motion, number, and solidity as primary qualities.

sense experience

Experiences given to us by our senses.

senses

Capacities that gives us experience of the external world. They include sight, hearing, smell, taste, touch and bodily awareness.

proposition

A declarative statement (or more accurately, what is claimed by a declarative statement), such as 'mice are mammals'. Propositions can go after 'that' in 'I believe that...' and 'I know that...'.

sensible quality

A property that can be detected by the senses.

propositional knowledge

Knowing 'that' some claim - a proposition - is true or false, e.g. 'I know that Paris is the capital of France'.

sufficient condition

One proposition is a sufficient condition for another when the first cannot be true while the second is false. For example, being a dog is sufficient for being an animal, because something can't be a dog without also being an animal.

synthetic

A proposition that is not analytic, but true or false depending on how the world is.

systematic correlation

A relationship between two things whereby a change in one is always accompanied by a change in the other.

reflection

Locke: Our experience of 'the internal operations of our minds', gained through introspection or an awareness of what the mind is doing. More generally, thinking.

time-lag argument

Against direct realism: Because it takes time for us to perceive physical objects, we don't see them directly. For example, as light takes 8 minutes to reach the earth from the sun, if you look at the sun you are actually seeing it as it was 8 minutes ago. Therefore, you are not perceiving the sun directly.

relations of ideas

Hume: Relations of ideas are established by pure thought or reflection and are 'intuitively and demonstratively certain'. The negation of a relation of ideas is a contradiction.

tripartite view of knowledge

Justified, true belief is necessary and sufficient for propositional knowledge (S knows that p if and only if S is justified in believing that p, p is true and S believes that p).

unperceived objects

Objects that exist when not perceived by anyone.

veridical

A proposition that is true or an experience that represents the world as it actually is.

virtue epistemology

S knows that p if and only if p is true, S believes that p, and S's belief that p is the result of S exercising their epistemic/intellectual virtues; in Zagzebski's definition, S knows that p if S believes that p and S's belief arises from an act of intellectual virtue

virtue, epistemic/intellectual

A skill, ability or trait or the mind or person that contributes to the good end of gaining knowledge and forming true beliefs.

waves of doubt

Descartes' three arguments supporting scepticism. The first, an argument from illusion, throws doubt on always believing what our senses tell us. The second, an argument from dreaming, throws doubt on all sense perception, and therefore on the nature of reality. The third, the possibility that an evil demon is deceiving us, throws doubt on all judgment, including the existence of a physical world and on the truths of mathematics.

secondary quality

Properties that physical objects have that are 'nothing but powers to produce various sensations in us'. Locke lists 'colours, sounds, tastes, and so on', later adding smells and temperature.

sense-data (singular sense-datum)

Mental images or representations of what is perceived, the 'content' of perceptual experience. If sense-data exist, they are the immediate objects of perception and are 'private', mind-dependent mental things.

solipsism

The view that only oneself, one's mind, exists. There no mind-independent physical objects and there are no other minds either.

tabula rasa

Latin for 'blank slate'. Locke claims that at birth our mind is a tabula rasa, meaning we have no innate knowledge or ideas.