CHSE Odisha Elective Logic key terms

The study of the standards by which arguments are judged correct or incorrect, focusing on the relation between premises and conclusion rather than on the psychological causes of belief.

A group of statements in which some, called premises, are offered as support for another, called the conclusion. A single statement alone is never an argument.

A statement in an argument offered as evidence or reason for accepting the conclusion. Premises may be true or false; their role is to support.

The statement an argument tries to establish, supported by the premises. It is what the arguer wants the audience to accept on the basis of the other statements.

The mental move from one or more statements to another statement taken to follow from them. Logic evaluates whether that move is justified.

A property of deductive arguments: the premises cannot all be true while the conclusion is false. Validity concerns form, not the actual truth of the premises.

A property of deductive arguments that are both valid and have all premises actually true. A sound argument therefore guarantees a true conclusion.

A word or phrase that can serve as the subject or predicate of a categorical proposition, standing for a class of things. Terms are the building blocks of categorical statements.

A statement that affirms or denies that one class is wholly or partly included in another, expressed in standard form with a quantifier, subject term, copula and predicate term.

A property of a term in a categorical proposition: the term is distributed when the statement says something about every member of the class it names.

A diagram showing logical relations among the four standard categorical forms: contradictory, contrary, subcontrary and subaltern relations, each with its own inference rules.

The relation between two propositions that cannot both be true and cannot both be false, so that the truth of one implies the falsity of the other and conversely.

An immediate inference that swaps the subject and predicate terms of a categorical proposition. It is valid without change of quantity only for E and I propositions.

An immediate inference that changes the quality of a proposition and replaces the predicate with its complement. It is valid for all four categorical forms.

A deductive argument with exactly three categorical propositions containing exactly three terms, each term appearing in two propositions, arranged so the premises yield the conclusion.

The predicate term of the conclusion of a categorical syllogism. It also appears in the major premise, which is conventionally stated first.

The term appearing in both premises of a categorical syllogism but not in the conclusion. It links the other two terms and must be distributed at least once.

The arrangement of the middle term in the two premises of a categorical syllogism. Four possible arrangements give the four figures.

The pattern of the four categorical proposition types (A, E, I, O) occurring in a syllogism, listed in the order major premise, minor premise, conclusion.

An error in reasoning that makes an argument logically defective, either because its form is invalid or because its persuasive force rests on something other than logical support.

A defect detectable purely from the logical form of an argument, such as affirming the consequent or undistributed middle, regardless of the subject matter discussed.

A reasoning error that depends on content, language or context rather than form alone, including relevance fallacies, ambiguity fallacies and presumption fallacies.

A fallacy in which the conclusion is assumed, explicitly or in disguised wording, among the premises, so the argument offers no independent support.

A compound proposition whose truth value is completely determined by the truth values of its component propositions, as with negation, conjunction, disjunction and the conditional.

A tabular display listing every possible combination of truth values for the component propositions of a formula and the resulting value of the whole formula.

The truth-functional conditional, false only when the antecedent is true and the consequent false. Everyday conditional claims are often read this way in propositional logic.

A compound proposition that is true under every possible assignment of truth values to its components, such as p or not-p. Its negation is a contradiction.

A valid inference rule: from a conditional and the affirmation of its antecedent, infer the consequent. Its Latin name means the mode that affirms.

A valid inference rule: from a conditional and the denial of its consequent, infer the denial of the antecedent. Denying the antecedent is a different, invalid pattern.

A proof technique that establishes a statement by assuming its negation and deriving a contradiction, thereby showing the original statement must be true.

An inference from observed cases to a claim about a whole population, whose strength depends on sample size, representativeness and the care taken in observation.

An inductive inference that because two things resemble each other in known respects, they probably resemble each other in a further respect. Relevance of similarities matters.

Reasoning that identifies cause and effect relations, commonly guided by Mill's methods of agreement, difference, concomitant variation and residues.

A testable proposed explanation or prediction offered for investigation. In science it must be checkable against evidence and open to confirmation or refutation.

A systematic procedure of observation, hypothesis formation, prediction, experiment or further observation, and revision of the hypothesis in the light of results.

The process of confirming a hypothesis by showing that its predicted consequences actually occur. Confirmation is usually a matter of degree rather than certainty.

The structure of an argument or statement abstracted from its specific subject matter, usually displayed with symbols, which determines whether the reasoning is valid.

A symbolic expression built according to the formation rules of a logical system, so that it has a definite truth value under each assignment of values to its variables.