Glossary & References

Knowledge or justification that depends directly on empirical evidence or sensory experience. Such propositions cannot be known through pure intellectual deduction alone.

Knowledge or justification that can be known independently of sensory experience, relying solely on conceptual analysis, formal deduction, or definitions. Its warrant does not rest on ongoing empirical observation.

A mode of inference that begins with an observation and forms the most likely or explanatory hypothesis to account for it. Often termed inference to the best explanation.

The state of lacking positive proof for a claim, which does not automatically constitute positive evidence for its falsity unless an exhaustive, highly sensitive investigation was conducted where evidence should have appeared.

An informal fallacy occurring when an argument attacks the personal traits, motives, background, or character of the advocate rather than engaging with the objective merits of their premise.

A formal logical fallacy where one infers the truth of an antecedent condition from the observed truth of its consequent conditional: If P then Q; Q; therefore P.

The flaw of formulating a term or premise using phrasing that supports multiple conflicting interpretations, obscuring whether an argument is valid or sound.

A fallacy of ambiguity resulting from loose or defective grammatical syntax rather than the double meaning of a single specific word.

Evidence derived from isolated personal testimony, informal stories, or individual incidents rather than systematic sampling and controlled empirical measurement.

The philosophical distinction between statements true purely by virtue of their meanings (analytic, such as 'all bachelors are unmarried') and statements whose truth depends on how the physical world actually is (synthetic).

An informal fallacy that substitutes an emotional reaction—such as pity, fear, or outrage—for relevant evidence and valid argumentation.

An informal fallacy asserting that a proposition must be true simply because it has not yet been proven false, or false simply because it has not yet been proven true.

Citing the endorsement of a prominent individual whose prestige or expertise lies outside the specialized domain of the claim being evaluated.

The fallacy of claiming that an idea, policy, or invention is inherently superior simply because it is newer, modern, or recently discovered.

An informal fallacy asserting that a proposition is true or desirable merely because a large majority or crowd of people believe it.

An informal fallacy arguing that an action or belief is justified solely because it has been practiced or accepted for generations.

A structured series of statements comprising one or more premises intended to provide inferential support, justification, or proof for a concluding proposition.

A premise, presupposition, or condition accepted as true or given without explicit defense or argument within a specific line of reasoning.

The unconditional baseline frequency, incidence, or percentage of an event or characteristic occurring within a given reference population.

A cognitive and probabilistic error where judgment focuses excessively on specific individual case features while ignoring the prior statistical prevalence of the phenomenon in the population.

An informal fallacy in which an argument's premises secretly assume the truth of the conclusion they are supposed to establish, yielding circular justification.

A psychological or cognitive state in which an agent takes an attitude of acceptance or assent toward a proposition, regarding it as true.

A compound logical connective expressing that two propositions have the exact same truth value: 'P if and only if Q' (P ↔ Q). It is true when both are true or both are false.

The epistemic obligation placed on the party making an affirmative or non-default claim to provide adequate justification, reasoning, or evidence for it.

A direct generative relationship between two events wherein the occurrence of the cause produces, brings about, or determines the occurrence of the effect.

The epistemic condition of being completely free from doubt or the possibility of error. Most contemporary epistemologists distinguish psychological conviction from objective certainty.

The selective presentation of evidence, studies, or observations that favor a predetermined stance while systematically suppressing or ignoring contradictory data.

A defect in reasoning where the conclusion is directly or indirectly used as a supporting premise, meaning the argument assumes the very thing it aims to prove.

A systematic, subconscious pattern of deviation from norm, logic, or rational probability in human judgment, judgment formation, and decision-making.

The epistemic theory that a belief is justified not by resting on foundational basic beliefs, but by fitting into a mutually reinforcing, harmonious web of other beliefs.

The erroneous inference that because every individual part or member of a system possesses a certain attribute, the whole system must also possess that attribute.

The core philosophical method of breaking complex, foundational concepts into their constituent necessary and sufficient conditions to clarify meaning and resolve paradoxes.

The principal proposition in an argument whose truth or probability the premises are offered to establish or support.

A hypothetical proposition of the form 'If P, then Q', where P is the antecedent condition and Q is the consequent outcome.

The error of conflating the probability of event A given B with the probability of event B given A: P(A|B) ≠ P(B|A).

The human tendency to search for, interpret, favor, and recall evidence in a way that confirms prior hypotheses while disregarding disconfirming evidence.

An unmeasured or extraneous factor that correlates with both the supposed cause and the supposed effect, creating a spurious statistical association.

A truth-functional connective ('and', denoted P ∧ Q) that produces a true proposition if and only if both conjuncts are simultaneously true.

A probabilistic error in which a person estimates that a compound condition (P and Q) is more probable than one of its single constituent conditions (P alone).

The property of a set of propositions such that it is logically possible for all of them to be true at the exact same time without generating contradiction.

A proposition that is neither necessarily true in all possible worlds (tautology) nor necessarily false (contradiction), but whose truth depends on how things actually are.

A proposition or conjunction of statements that asserts both P and not-P at the same time and in the same respect, which is logically impossible to be true.

A mutual statistical relationship or association between two variables, such that changes in one accompany predictable changes in the other.

A specific instance, specimen, or case that directly refutes a universal claim, rule, or proposed definition by demonstrating its failure.

A form of reasoning in which the conclusion necessarily follows from the premises; if all premises are true and the argument form is valid, the conclusion cannot be false.

A formal logical fallacy where one infers the falsity of the consequent from the falsity of the antecedent: If P then Q; not P; therefore not Q.

A statement asserting how the world, reality, or state of affairs actually is, verifiable or falsifiable through empirical observation or logical analysis.

A truth-functional connective ('or', denoted P ∨ Q) which, in standard logic, is inclusive: true if either conjunct is true, or if both are true.

A valid deductive inference rule of the form: P or Q; Not P; Therefore Q.

The erroneous inference that because an entire system or whole entity possesses a certain property, each of its individual constituent parts must also possess it.

The metaphysical position that reality consists of two fundamentally distinct categories of substances, properties, or entities, typically mental and physical.

The epistemological theory asserting that substantive knowledge arises primarily through sensory perception, experimental observation, and inductive generalization.

The core branch of philosophy concerned with the nature, origin, scope, justification, and limits of knowledge and rational belief.

An informal fallacy that exploits multiple distinct meanings of a single word or phrase within an argument, treating them as identical to reach a deceptive conclusion.

The misleading presentation of rough heuristic approximations, model extrapolations, or speculative estimates as if they were pin-point empirical measurements.

Facts, documentation, observational data, or reasoned demonstrations that serve to increase or decrease the epistemic probability of a hypothesis.

High-level specialized domain competence, methodological training, and empirical mastery recognized through peer evaluation, credentials, and sustained track records.

The epistemological thesis that factors external to an agent's conscious awareness—such as reliable causal cognitive mechanisms—determine whether a belief is justified or counts as knowledge.

A defect or flaw in reasoning that impairs the logical validity or evidentiary soundness of an argument, rendering its conclusion unearned.

The epistemological principle that empirical knowledge can never be claimed with absolute, Cartesian certainty, and that any of our beliefs could conceivably turn out to be mistaken.

An informal fallacy that artificially constrains a complex spectrum of possibilities into only two mutually exclusive extremes, ignoring viable middle alternatives.

The methodological requirement formulated by Karl Popper that an empirical scientific hypothesis must make testable predictions capable of being shown false by observation.

A defect in the structural form or syntax of a deductive argument that renders the inference invalid, regardless of whether the premises happen to be factually true.

The epistemic doctrine that all knowledge and justified beliefs ultimately rest upon basic beliefs that are self-justifying or directly warranted without needing further inference.

The mistaken belief that past independent random outcomes influence the probability of the next independent random trial in a Bernoulli sequence.

Evaluating the truth or validity of an assertion solely by examining its historical origin, causal lineage, or how it arose, rather than testing its independent justification.

A philosophical thought experiment demonstrating that justified true belief (JTB) is not sufficient for knowledge, because luck or epistemic coincidence can connect the belief to the truth.

Drawing a sweeping universal conclusion about an entire population based on an unrepresentative, biased, or tiny sample size.

A proposed, provisional explanation or testable conjecture for an observed phenomenon, offered as a starting point for further empirical investigation.

A valid deductive inference rule linking conditional statements in a transitive chain: If P then Q; If Q then R; Therefore, If P then R.

The metaphysical thesis that reality, or reality as we know it, is fundamentally mental, immaterial, or constituted by ideas, minds, or perceptions.

The error of treating a statistical estimate as a certain scalar number while neglecting the margin of error or confidence intervals accompanying it.

An umbrella term for invalid deductive moves on conditional propositions, including affirming the consequent and denying the antecedent.

A mode of reasoning that draws probabilistic, generalized conclusions from finite sets of specific observations, where true premises render the conclusion probable but not logically certain.

An abductive principle that licenses accepting a hypothesis if it provides a superior, simpler, and more coherent explanatory account of observed phenomena than rival hypotheses.

The epistemological theory that justification is an infinite, non-repeating chain of reasons, rejecting both foundational stopping points and circular webs.

A defect in reasoning that depends on the substantive content, context, or semantics of an argument rather than its formal deductive structure.

The epistemological view that the factors determining the justification of a belief must be cognitively internal and accessible to the believer's conscious reflection.

The property of a deductive argument whose structural form fails to guarantee that if all its premises are true, its conclusion must also be true.

A formal fallacy in term logic where the subject and predicate of a universal affirmative proposition are swapped without qualification: converting 'All S is P' into 'All P is S'.

The rational ground, evidence, argument, or reliable cognitive warrant that confers epistemic legitimacy on a belief.

The traditional tripartite definition of propositional knowledge dating to Plato, holding that an agent knows that P if and only if P is true, the agent believes P, and the agent is justified in believing P.

Cognitive grasp of objective reality characterized by truth, adequate epistemic justification or warrant, and immunity to Gettier-style epistemic accidents.

An informal fallacy consisting of a question containing an unjustified, unproven presumption of guilt or fact built into its presupposition.

The relationship between two propositions that necessarily share the exact same truth value under all possible truth-value assignments.

The branch of philosophy that investigates the fundamental nature of reality, existence, identity, causation, time, space, and being.

False, inaccurate, or misleading information communicated regardless of whether there is deliberate intent to deceive.

Structuring how a situation, statistic, or argument is verbally presented to evoke a biased conclusion while omitting crucial context.

Using a data sample that is systematically unrepresentative of the target population to infer a general claim.

Conflating statistical significance (p < 0.05) with substantive, practical, or clinical importance in the physical world.

A conceptual, mathematical, or computational representation of an empirical system designed to simulate its behavior and generate testable predictions.

The fundamental valid deductive rule of inference asserting that if a conditional statement is true and its antecedent is true, its consequent must be true: If P then Q; P; therefore Q.

The valid deductive rule of inference asserting that if a conditional statement is true and its consequent is false, its antecedent must also be false: If P then Q; Not Q; therefore Not P.

An informal fallacy where an arguer arbitrarily changes the accepted criteria of proof or evidence as soon as the initial criteria have been successfully satisfied.

A requirement that must be satisfied for a condition or statement to hold true; without it, the condition cannot occur.

The unary logical operator ('not', denoted ¬P) that inverts the truth value of a proposition, turning true into false and false into true.

The error of treating an underpowered study that failed to reach statistical significance (p > 0.05) as definitive proof that the phenomenon does not exist.

An informal fallacy where an arguer protects a universal generalization from a clear counterexample by arbitrarily redefining membership in the category to exclude the case.

A statement asserting how things ought to be, what is good or bad, or which actions are morally obligatory, rather than merely describing what is.

The subfield of metaphysics focused specifically on the taxonomy of being, studying what categories of entities fundamentally exist.

Attributing an outcome driven by complex multifactorial causes to a single isolated variable.

An apparently sound argument originating from seemingly true premises that leads to a conclusion that is self-contradictory or completely unacceptable.

The metaphysical thesis that everything in reality is ultimately physical, and that all mental, biological, and social properties supervene on fundamental physical processes.

The informal causal fallacy of inferring that because event Y occurred immediately after event X, event X must have caused event Y.

A proposition in an argument offered as foundational support or evidence from which a conclusion is inferred.

An immediate, first-hand artifact, recorded empirical dataset, or original text created at the time under study by direct participants.

The methodological norm requiring an analyst to interpret an interlocutor's argument in its strongest, most coherent, and most rational form before critiquing it.

A fallacy of statistical reasoning where the probability of a match given innocence P(Match|Innocent) is conflated with the probability of innocence given a match P(Innocent|Match).

A logical operator that specifies the quantity of specimens in the domain of discourse that satisfy a given open predicate, primarily universal (∀, 'for all') and existential (∃, 'there exists').

The epistemological theory asserting that reason, deduction, and innate intellectual intuition are the primary sources and tests of knowledge, distinct from sensory perception.

The metaphysical and epistemological view that reality exists independently of our conceptual frameworks, beliefs, perceptions, or linguistic descriptions.

An informal fallacy where an arguer introduces an irrelevant, distracting topic into a discussion to divert attention away from the core issue.

A valid form of deductive refutation that disproves a proposition by showing that assuming its truth leads inexorably to a logical contradiction or absurd consequence.

A state of dynamic balance arrived at by deliberative mutual adjustment between our general principles and our considered judgments about specific cases.

The statistical phenomenon where extreme or unusual measurements are naturally followed by subsequent measurements that lie closer to the population average.

The fallacy of treating an abstract concept, metaphor, or heuristic model as if it were a concrete, physically existing entity with causal agency.

The confusion or misleading framing that occurs when changes in probability are reported as dramatic relative percentages rather than modest absolute changes.

The externalist epistemological theory holding that a belief is justified if and only if it is generated by a cognitive process that reliably produces a high ratio of true beliefs.

The causal fallacy of inverting directionality between cause and effect, misinterpreting the consequence as the trigger.

The practice of publishing or publicizing only the empirical trials or sub-analyses that yield statistically significant or desirable findings.

Nick Bostrom's trilemma argument showing that at least one of three propositions is almost certainly true: humanity goes extinct before reaching posthuman technological capability, posthuman civilizations lose interest in running ancestor simulations, or we are almost certainly living in a simulation.

The philosophical stance or inquiry questioning the certainty, reliability, or foundational grounds of knowledge claims.

An informal fallacy asserting that taking a relatively modest initial step will inevitably lead through an uncontrollable chain reaction to a catastrophic outcome, without establishing causal links.

The property of a deductive argument that is both structurally valid AND whose premises are all factually true in the real world, guaranteeing a true conclusion.

An informal fallacy wherein an arguer applies a rigorous standard or rule to others while exempting themselves without providing a justifiable, non-arbitrary reason.

The practice of reconstructing an opposing argument in its strongest, most sophisticated, and most defensible form before proceeding to evaluate its merits.

An informal fallacy in which an opponent's actual argument is mischaracterized, exaggerated, or distorted into a weaker version that is easier to attack and refute.

A condition that, if satisfied, entirely guarantees the truth or occurrence of another event or statement.

A logical and statistical error that focuses only on successful or surviving specimens that passed an ordeal while ignoring those that failed, skewing conclusions.

A classic form of deductive argument comprising three propositions: a major premise, a minor premise, and a conclusion derived through term analysis.

A compound proposition in formal logic that evaluates to true under every possible assignment of truth values to its constituent atomic variables.

An epistemic source of belief and knowledge based on what other persons communicate, assert, or document.

The fallacy of cherry-picking clusters of data or coincidences within random scatter and retrospectively drawing a bullseye target around them to claim meaning.

A comprehensive, structured explanatory framework validated by extensive predictive accuracy, falsifiability testing, and widespread scientific consensus.

An imaginative, controlled mental scenario designed to isolate conceptual principles, expose logical contradictions, or test the implications of a hypothesis.

The property of a proposition corresponding to objective reality, state of affairs, or factual being.

A specific variant of the ad hominem fallacy that attempts to discredit an argument by pointing out that the speaker has acted inconsistently with their own claim.

The state of lacking complete knowledge or exact predictability regarding outcomes, parameter measurements, or future events.

A formal syllogistic fallacy occurring when the middle term connecting the premises is not distributed in at least one premise.

The structural property of a deductive argument such that it is logically impossible for its premises to be true while its conclusion is false.

An approach to epistemology that evaluates the intellectual virtues, cognitive character traits, and conscientious motivations of the thinker rather than assessing beliefs in isolation.

An informal fallacy that assumes because two things are similar in one superficial respect, they must also be similar in another substantive, unrelated respect.

A number from 0 to 1 measuring how likely an outcome is, or how strongly the evidence supports a claim. Philosophers and statisticians disagree about what exactly it measures, but the arithmetic rules are shared.

Based on observation, measurement or experiment rather than on reasoning alone.

The 'if' part of a conditional statement. In 'If P then Q', P is the antecedent and Q is the consequent.

A rule for updating a probability when new evidence arrives: P(H|E) = P(E|H) × P(H) / P(E). It shows why the starting (base-rate) probability matters.

An invented scenario or number used only to demonstrate an idea. It is not a claim about the real world.