Maharashtra HSC Logic key terms

The branch of study that distinguishes correct from incorrect reasoning by setting out rules that a conclusion must satisfy if it is to follow necessarily from given premises.

The meaning expressed by a declarative sentence, which is either true or false and which remains the same even when phrased in different words or languages.

A word or group of words that can serve as the subject or predicate of a categorical proposition, standing for a class of things rather than asserting anything on its own.

A group of propositions in which some, called premises, are offered as evidence, and another, called the conclusion, is claimed to be supported by them.

A proposition in an argument that is put forward as a reason or piece of evidence intended to support the conclusion, not as the claim being established.

The proposition in an argument that the premises are meant to establish; it is the claim the arguer wants the audience to accept on the basis of the other propositions.

The mental step by which one moves from one or more propositions already accepted to a further proposition taken to be supported by them.

The classification of a proposition as either true or false; in classical two-valued logic every proposition has exactly one of these two values.

An argument whose premises are claimed to guarantee the conclusion, so that if the premises are true the conclusion cannot possibly be false.

An argument in which the premises are claimed to make the conclusion probable, so that the conclusion goes beyond what the premises strictly guarantee.

A property of deductive arguments whereby the conclusion follows necessarily from the premises: it is impossible for all premises to be true while the conclusion is false.

A property of deductive arguments that are both valid and have all their premises actually true, so the conclusion is guaranteed to be true as well.

A proposition that asserts or denies that one class is wholly or partly included in another, using the standard forms All S are P, No S are P, Some S are P, Some S are not P.

The aspect of a categorical proposition that determines whether it speaks about the whole subject class (universal) or only part of it (particular).

The aspect of a categorical proposition that determines whether it affirms class inclusion (affirmative) or denies it (negative).

The status of a term in a categorical proposition when the proposition says something about every member of the class that term names.

A term used in a proposition in such a way that the proposition applies to all members of the class it designates, as the subject of a universal does.

An inference that draws a new proposition from a single premise, without any second proposition being needed, as in conversion, obversion and contraposition.

An immediate inference that swaps the subject and predicate of a categorical proposition while leaving quality unchanged, valid without limitation only for E and I propositions.

An immediate inference that changes the quality of a proposition and replaces the predicate with its complement, yielding a logically equivalent proposition for all four standard forms.

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

The term that appears in both premises of a categorical syllogism but not in the conclusion, linking the other two terms together.

The predicate of the conclusion of a categorical syllogism, which also appears in the major premise together with the middle term.

The subject of the conclusion of a categorical syllogism, which also appears in the minor premise together with the middle term.

The arrangement of the middle term in the two premises of a categorical syllogism; four possible arrangements are traditionally distinguished and each permits only certain moods.

The pattern of the four proposition types (A, E, I, O) that make up the premises and conclusion of a categorical syllogism, written as a three-letter sequence.

Words or symbols such as not, and, or, and if-then that join simple propositions into compound ones and whose meaning is fixed by truth tables.

A proposition built from one or more simpler propositions by means of logical connectives, so that its truth value depends on theirs.

A systematic chart listing every possible combination of truth values for the component propositions of a formula and showing the resulting value of the whole formula.

A compound proposition that comes out true under every possible assignment of truth values to its components, as shown by a truth table whose final column is all true.

A compound proposition that is false under every possible assignment of truth values to its components, so its truth table's final column contains only false.

The truth function expressed by if-then, which is false only when the antecedent is true and the consequent false, and true in the other three cases.

A step-by-step derivation of a conclusion from premises using stated rules of inference and replacement, each step justified by a named rule.

A licensed pattern of derivation permitting a new line to be written in a proof, such as modus ponens or simplification, valid for all substitutions of its variables.

A rule of inference holding that from a conditional and the affirmation of its antecedent one may infer its consequent.

A rule of inference holding that from a conditional and the denial of its consequent one may infer the denial of its antecedent.

A proof technique that assumes the negation of what is to be proved, derives a contradiction from that assumption, and concludes that the original proposition must be true.

A proof technique for establishing a conditional by temporarily assuming its antecedent and deriving its consequent, then discharging the assumption.

A proposed explanation or generalization put forward for testing, from which observable consequences are deduced and then checked against evidence.

An inductive argument that concludes something about one case because it resembles another case in relevant respects already known to have a certain property.

Five procedures for identifying causes by comparing instances, namely agreement, difference, joint agreement and difference, residues, and concomitant variation.

A defect in reasoning that makes an argument logically weak even though it may appear persuasive, often because it appeals to emotion or ignores relevant considerations.

A fallacy in which an argument assumes as a premise the very conclusion it is supposed to establish, so the reasoning moves in a circle.

The fallacy of arguing for a conclusion other than the one at issue, so that the premises support a different claim than the one actually being defended.

The fault of a word or sentence having more than one possible meaning, which can make an argument appear valid only by shifting meaning between premises.