Assam HS Class 11-12 Logic and Philosophy flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Argument

A group of propositions in which some, the premises, are claimed to provide support for another, the conclusion. A single proposition is never an argument.

Validity

A property of deductive arguments: the conclusion follows necessarily from the premises, so it is impossible for the premises to be true and the conclusion false.

Soundness

A deductive argument is sound when it is valid and all its premises are actually true. Soundness guarantees a true conclusion; validity alone does not.

Inductive argument

An argument whose conclusion is claimed to follow only probably from the premises. It is assessed as strong or weak, cogent or uncogent, never as valid or invalid.

Intension and extension

A term's intension is the set of attributes it implies; its extension is the class of objects it denotes. Increasing intension generally decreases extension.

Equivocal term

A term used with different meanings in different occurrences within the same context, which can make an argument invalid through the fallacy of four terms.

Genus and difference

An intensional definition that places a term in a wider class, the genus, and states the distinguishing feature, the specific difference, that separates it.

Persuasive definition

A definition that uses emotive or evaluative language to influence attitudes while appearing to state a neutral meaning; common in rhetoric and advertising.

Categorical proposition

A proposition linking subject and predicate with a copula, having explicit or implicit quantity (universal or particular) and quality (affirmative or negative).

A, E, I, O forms

The four standard categorical forms: All S are P (A), No S are P (E), Some S are P (I), Some S are not P (O).

Square of opposition

A diagram showing truth relations among A, E, I, O: contradictories differ in truth value, contraries cannot both be true, subcontraries cannot both be false.

Existential import

The assumption that the subject class of a proposition has members. Traditional logic assumes it for universals; modern Boolean logic does not.

Distribution of terms

A term is distributed when the proposition asserts something about every member of the class it denotes. A distributes subject; E both; I neither; O predicate.

Conversion

Immediate inference that swaps subject and predicate. Valid for E and I unchanged; A converts only by limitation to I; O cannot be converted.

Obversion

Immediate inference that changes quality and replaces the predicate with its complement. Valid for all four categorical forms and preserves truth value.

Contraposition

Immediate inference obtained by obverting, converting, and obverting again. Valid for A and O propositions; invalid for E and I.

Middle term

The term appearing in both premises of a categorical syllogism but never in the conclusion. It must be distributed at least once for validity.

Undistributed middle

A formal fallacy in which the middle term is not distributed in either premise, so the premises fail to connect subject and predicate classes.

Mood and figure

Mood is the ordered letters of a syllogism's propositions; figure is determined by the middle term's position. Together they identify forms like AAA-1.

Illicit process

A formal fallacy in which a term is distributed in the conclusion but not in the premise, either illicit major or illicit minor.

Material implication

The conditional p⊃q is false only when p is true and q is false; it is equivalent to ~p∨q and to ~(p·~q).

Tautology

A compound proposition true on every row of its truth table, such as p∨~p. Its negation is a contradiction, false on every row.

Modus ponens

A valid argument form: if p then q; p; therefore q. It affirms the antecedent and yields the consequent as conclusion.

Modus tollens

A valid argument form: if p then q; not q; therefore not p. It denies the consequent and concludes the denial of the antecedent.

De Morgan's laws

Two equivalence rules: the negation of a conjunction is the disjunction of the negations, and the negation of a disjunction is the conjunction of the negations.

Mill's method of difference

A causal method comparing two instances that differ in one circumstance and in the effect; the single differing circumstance is identified as the cause.

Argument by analogy

An inductive argument claiming that because two things share known similarities, they probably share a further similarity. Strength depends on relevant similarities and disanalogies.

Hypothetico-deductive method

A scientific procedure: formulate a hypothesis, deduce testable consequences, then confirm or refute the hypothesis by observation and experiment.

Cogent argument

An inductive argument that is strong and has all true premises. Cogency, not validity, is the standard of merit for inductive reasoning.

Justified true belief

The traditional analysis of knowledge: a belief is knowledge if it is true and the believer has adequate justification. Gettier cases challenge its sufficiency.

Rationalism and empiricism

Rationalism holds reason is the primary source of knowledge; empiricism holds experience is. Descartes and Hume are classic representatives of each.

Anekāntavāda

The Jaina doctrine of many-sidedness: reality is complex, so every judgment is qualified. It grounds syādvāda, the seven-fold predication scheme.

Nyāya pramāṇas

The four means of valid knowledge in Nyāya: perception, inference, comparison, and verbal testimony. Cārvāka accepts only perception; Buddhism accepts two.