Glossary of philosophy and science terms

115 terms from the amphi courses, each with a plain definition and the sources behind it.

A

a priori: A priori knowledge is justified without appeal to experience, the way arithmetic is.
Adaptation: An adaptation is a trait that exists in its current form because natural selection favoured it for the function it now performs.
aesthetics: The study of art, beauty and taste, and of the judgements people make about them.
Algorithm: An algorithm is a finite list of unambiguous instructions that solves every problem of a given kind in a finite number of steps.
Allele: An allele is one of the alternative versions a gene can take at a given position on a chromosome.
Ataraxia: Ataraxia is a state of freedom from mental disturbance, often translated as 'tranquility' or 'imperturbability.' Several Hellenistic schools, including the Stoics, the Epicureans, and the Skeptics, treated it as a central goal, though they disagreed sharply about how to reach it.
Attachment: Attachment is the strong, selective bond an infant forms with the small number of adults who care for it, and Bowlby's claim was that this bond is a biological system rather than a by-product of being fed.
Authority and legitimacy: Authority is the right to issue commands that others have reason to obey, as distinct from the sheer power to make them comply.
Axiom: An axiom is a statement accepted without proof and used as a starting point for everything else in a subject.

B

Bad faith: Bad faith is Sartre's term for the ways people deceive themselves about their own freedom.
Blackbody radiation: Any object that absorbs all light falling on it also glows, and the colour of that glow depends only on its temperature, not on what it is made of.

C

Cardinality and infinity: Cardinality is the size of a set, measured by trying to match its members one to one with the members of another set.
Categorical imperative: The categorical imperative is Kant's test for whether an action is morally permitted.
Civil disobedience: Civil disobedience is a public breach of law undertaken to protest a law or policy, by someone who accepts the legal consequences of the act.
Class: Class divides a society into groups defined by their position in its economic order.
Classical conditioning: Classical conditioning is learning by association: a signal that predicts something biologically important starts to produce the response the important thing produces.
Cogito ergo sum: Cogito ergo sum, Latin for 'I think, therefore I am,' is the point Descartes reaches in his Meditations after doubting everything he possibly can, including the reliability of his senses and the existence of the external world.
Cognitive dissonance: Cognitive dissonance is the discomfort of holding two beliefs, or a belief and an action, that do not fit together, and the pressure that discomfort creates to change one of them.
Common descent: Common descent is the claim that any two living organisms share an ancestor if you go back far enough, and that all known life descends from a single ancestral population.
Conformity: Conformity is changing a judgement or an action to match a group.
Conjecture: A conjecture is a statement believed to be true but not yet proved.
Conservation law: A conservation law states that some measurable quantity in an isolated system stays the same as the system evolves.
Construct validity: Construct validity asks whether a measure actually captures the thing it claims to capture.
Continuity: A function is continuous when small changes to the input produce only small changes to the output, so its graph has no jumps or breaks.

D

Defence mechanism: A defence mechanism is an unconscious strategy that protects a person from anxiety by distorting how a threatening fact is registered.
Democracy: Democracy is rule by the people, usually through some combination of voting, competitive elections, and protections that allow citizens to organise, publish and criticise those in power.
Derivative: The derivative of a function measures how fast its output changes at a single instant, rather than on average over an interval.
determinism: The view that every event is fixed by earlier events together with the laws of nature, so that given the past, only one future is possible.
Developmental stage: A developmental stage is a period in which a child's thinking is organised in a distinctive way, so that development is treated as a sequence of qualitative reorganisations rather than a steady accumulation of facts.
Dialectic: Dialectic is a method of arriving at truth through structured disagreement.

E

Ecological niche: A niche is the set of conditions a species can persist in and the role it plays where it does: what it eats, what eats it, what temperature and moisture it tolerates, and what it competes with.
Ecosystem: An ecosystem is a community of organisms together with the physical environment they exchange energy and matter with, treated as one unit.
Effect size: An effect size states how large a difference or relationship is, in contrast to a p-value, which states only how unlikely the data would be if there were no effect at all.
Energy: Energy is the quantity that measures a system's capacity to do work, and it takes many forms: motion, position in a field, heat, radiation, chemical bonds, and mass itself.
Entropy: Entropy measures how many microscopic arrangements of a system are consistent with what you can observe about it from outside.
epistemology: The study of knowledge: what it is, how it is gained, and when a belief counts as justified.
Equality: Equality in political thought is the claim that people are in some fundamental respect equals of one another, and that political arrangements should reflect this.
Eternal recurrence: Eternal recurrence is the thought experiment Nietzsche poses in The Gay Science and develops in Thus Spoke Zarathustra: imagine that your life, in every detail, will repeat itself infinitely, exactly as it happened.
ethics: The study of how to act and of what makes an action right or wrong.
Eudaimonia: Eudaimonia is usually translated as 'happiness' or 'flourishing,' though neither translation is exact.

F

Federalism: Federalism divides authority between a central government and regional units, with each holding powers the other cannot simply revoke.
Field: A field assigns a value to every point in space and time.
Fitness: Fitness in biology is not strength or health but expected reproductive contribution: how many offspring an organism or a genotype leaves relative to the alternatives in the same population.
Force: A force is an interaction that changes the motion of an object.
free will: The kind of control over your own actions that makes praise, blame and responsibility appropriate.
Function: A function assigns exactly one output to each allowed input.
Fundamental attribution error: The fundamental attribution error is the tendency to explain other people's behaviour by their character while explaining the same behaviour in oneself by the situation.

G

Gene: A gene is a stretch of DNA that carries the instructions for a product, usually a protein or a functional RNA.
Genetic drift: Genetic drift is change in allele frequencies caused by sampling error rather than by any difference in fitness.
Genotype and phenotype: The genotype is the set of alleles an organism carries; the phenotype is what the organism actually turns out to be, from its height and colouring to its behaviour and its blood chemistry.
Golden mean: The golden mean is Aristotle's principle that virtue lies between two vices, one of excess and one of deficiency, relative to the particular person and situation.
Group: A group is a set together with one operation that combines any two members to give a third, subject to three conditions: the operation is associative, there is an identity element that changes nothing, and every element has an inverse that undoes it.

H

Heredity: Heredity is the passing of traits from parents to offspring.
Heuristics and biases: A heuristic is a mental shortcut that produces a usable answer quickly without working the problem through.
Homeostasis: Homeostasis is the maintenance of a stable internal state while the outside world changes.

I

Ideology: An ideology is a connected set of beliefs about how society works and how it ought to be arranged, held widely enough to guide political action.
Incompleteness: Gödel's first incompleteness theorem, published in 1931, says that any consistent formal system with rules strong enough to express basic arithmetic contains statements that are true of the numbers but cannot be proved inside the system.
Inertial frame: An inertial frame is a point of view from which an object with no forces acting on it moves in a straight line at a constant speed.
Integral: An integral totals up a quantity that varies continuously, most often the area under a curve, by adding many thin approximating pieces and taking the limit as the pieces get thinner.
Intelligence and its measurement: Intelligence testing began as a practical tool: Alfred Binet and Théodore Simon built a scale in 1905 to identify French schoolchildren who needed extra help, by comparing a child's performance against what was typical for their age.
Isomorphism: An isomorphism is a matching between two structures that pairs their members one to one and preserves every operation, so that anything true of one structure in its own terms is true of the other.

J

Justice: Justice is the standard by which the basic arrangements of a society - who holds what, who decides what, who answers for what - are judged right or wrong.

L

Leap of faith: The leap of faith is Kierkegaard's description of the move required to become a genuine believer: a commitment made without, and sometimes against, rational proof or objective certainty.
Limit: A limit is the value a quantity approaches as its input is brought arbitrarily close to some point, whether or not the quantity ever reaches that value.

M

Measurement problem: Quantum mechanics gives two rules that do not fit together.
Metabolism: Metabolism is the set of chemical reactions that keep a cell running: breaking molecules down to release energy, and building molecules up to make and repair structures.
metaphysics: The study of what exists and what reality is like at its most general: objects, properties, cause, time, possibility.
Momentum: Momentum is mass multiplied by velocity, and it points in the direction the object is moving.
Mutation: A mutation is a change in a DNA sequence.

N

Natural selection: Natural selection follows from three facts about a population: individuals vary, some of that variation is heritable, and more offspring are produced than can survive.
Nature versus nurture: The nature-nurture question asks how much of the variation between people comes from inherited differences and how much from environment and experience.
Negative and positive liberty: Negative liberty is freedom from interference: you are free to the extent that nobody is stopping you.
Noether's theorem: Noether's theorem, proved in 1918, states that every continuous symmetry of a physical system corresponds to a conserved quantity.
Non-Euclidean geometry: Non-Euclidean geometry is what results from keeping Euclid's other assumptions and replacing his parallel postulate, which says that through a point not on a given line there passes exactly one line parallel to it.
normative: Normative claims say how things ought to be or what someone should do.

O

ontology: The part of metaphysics that asks what kinds of thing exist and how they relate.
Operant conditioning: Operant conditioning is learning from consequences: behaviour that is followed by a good outcome becomes more frequent, and behaviour followed by a bad one becomes less frequent.

P

phenomenology: The study of experience as it is lived, described from the first person rather than explained from outside.
Phylogeny: A phylogeny is the branching history of descent that connects a set of organisms, and a phylogenetic tree is a diagram of that history inferred from evidence.
Plato's theory of forms: Plato's theory of forms holds that beyond the physical world we perceive with our senses, there exists a realm of perfect, unchanging forms that physical things only imitate or participate in.
Political obligation: Political obligation is the question of whether, and why, you are morally required to obey the law of the state you happen to live under.
Prime number: A prime is a whole number greater than 1 whose only divisors are 1 and itself: 2, 3, 5, 7, 11, and so on.
Probability: Probability assigns a number between 0 and 1 to an event, with 0 meaning impossible and 1 meaning certain.
Proof: A proof is a chain of reasoning showing that a statement follows with certainty from things already accepted.

Q

Quantum superposition: If a quantum system can be in state A and can be in state B, then it can also be in a combination of both, called a superposition.

R

Reinforcement: Reinforcement is any consequence that makes the behaviour it follows more likely to happen again.
Relativity of simultaneity: Two events that happen at the same moment according to one observer can happen at different moments according to another observer moving relative to the first.
Representation: Representation is the arrangement by which some people act politically in the name of others.
Rights: A right is a claim that others, including the state, are required to respect.

S

Self-efficacy: Self-efficacy is a person's belief that they can carry out the actions a particular situation requires.
Separation of powers: The separation of powers divides a government into branches - typically legislative, executive and judicial - and assigns each a distinct function, so that no single body both makes the law and enforces it.
Set: A set is a collection of objects treated as a single object in its own right.
Sovereignty: Sovereignty is supreme authority within a territory: the claim that the decisions of some body are final and not reviewable by any higher earthly power.
Spacetime: Spacetime treats the three dimensions of space and the one of time as a single four-dimensional structure rather than as a stage and a clock kept separately.
Species: A species is the basic unit biologists count populations in, but there is no single agreed definition of it.
Symmetry: In physics a symmetry is a change you can make to a system that leaves its behaviour unaltered.

T

Tabula rasa: Tabula rasa, Latin for 'blank slate,' is the idea that the mind starts with no innate ideas or built-in content and is shaped entirely by experience.
The absurd: The absurd is the conflict between the human need for meaning and a universe that offers none.
The cell: A cell is the smallest unit that counts as alive: a volume of chemistry enclosed by a membrane that keeps its inside different from its outside.
The central dogma: The central dogma is Crick's statement about the direction in which sequence information moves: from nucleic acid to nucleic acid or from nucleic acid to protein, but never back out of a protein into a nucleic acid.
The greatest happiness principle: The greatest happiness principle states that the right action is the one that produces the greatest overall happiness for the greatest number of people affected by it.
The public good: The public or common good is the set of conditions that benefit a political community as a whole rather than any particular part of it: working courts, clean air, public safety, an educated population.
The replication crisis: The replication crisis is the finding, from the early 2010s onward, that a large share of published psychological results do not reappear when the studies are run again.
The rule of law: The rule of law is the requirement that power be exercised through general, public and reasonably stable rules applied by independent courts, rather than by particular commands issued by officials.
The social contract: The social contract is the idea that political authority rests on an agreement among the governed rather than on divine right, conquest, or natural hierarchy.
The speed of light as a limit: Light in vacuum travels at a fixed speed, about 300,000 kilometres per second, and this speed is the same for every observer regardless of how fast the source or the observer is moving.
The state: A state is a political organisation that claims final authority over a defined territory and the people in it, and that maintains institutions - courts, police, armed forces, tax collection - to make the claim effective.
The unconscious: The unconscious, in Freud's sense, is the part of mental life that shapes what a person feels and does while staying out of reach of deliberate recall.
Theorem: A theorem is a statement that has been proved from the axioms and definitions of its subject.
Thermodynamic equilibrium: A system is in thermodynamic equilibrium when its large-scale properties, such as temperature, pressure, and composition, have stopped changing and there is no net flow of heat or matter within it or across its boundary.

U

Übermensch: The Übermensch, usually translated as 'overman' or 'superman,' is the figure Nietzsche uses in Thus Spoke Zarathustra to describe someone who creates their own values after the death of God has removed inherited ones.
Uncertainty principle: The uncertainty principle, stated by Heisenberg in 1927, says that certain pairs of properties cannot both have sharp values at the same time.

W

Wave-particle duality: Light behaves as a wave in some experiments, spreading and interfering, and as a stream of discrete particles in others, arriving one packet at a time.
Will to power: Will to power is Nietzsche's proposal that the basic drive in living things is not survival or pleasure but the drive to grow, expand, and exert one's own strength, including over oneself.
Working memory: Working memory is the small amount of information a person can hold active and manipulate at one time, as distinct from long-term memory, which is storage.