Reasoning and critical thinking test 1
Claim or proposition :: A statement capable of being true or false.
Argument :: A set of premises, a conclusion, and an inference connecting the premises to the conclusion.
Premise :: A claim presented as a reason or as evidence supporting a conclusion.
Conclusion :: The claim that an argument is intended to establish.
Inference :: The reasoning step connecting premises to a conclusion.
Premise indicator :: A word or expression that often introduces a premise, such as because, since, given that, or considering that.
Conclusion indicator :: A word or expression that often introduces a conclusion, such as therefore, thus, hence, so, or it follows that.
Explanation :: A passage that assumes something is true and gives reasons why it is true.
Argument versus explanation :: An argument tries to establish that something is true; an explanation assumes it is true and explains why.
Simple argument :: An argument containing one inference and one conclusion.
Complex argument :: An argument containing multiple connected inferences.
Subargument :: A smaller argument contained within a complex argument.
Intermediate conclusion :: A conclusion supported by earlier premises that is subsequently used as a premise.
Final conclusion :: The ultimate conclusion that the complete argument is intended to establish.
Standard form :: A numbered presentation that separates premises and conclusions and states which premises support each conclusion.
Principle of charity :: The practice of selecting the strongest reasonable interpretation compatible with what an arguer said.
Inference form or pattern :: The general reasoning structure shared by different arguments.
Unstated premise :: A premise required by an argument but left implicit by the arguer.
Unstated conclusion :: A conclusion intended by an argument but not explicitly stated.
Argument diagram :: A visual representation showing which premises support which conclusions.
Independent premises :: Premises that each provide support for a conclusion separately.
Linked premises :: Premises that provide support only when considered together.
Rational acceptability :: The degree to which it is reasonable to accept a claim, even when it is not absolutely certain.
Entertaining a premise for the sake of argument :: Temporarily assuming a claim in order to determine what would follow if it were true.
Scope :: The number or range of objects covered by a claim.
Particular claim :: A claim stating that at least one object of a certain kind has or lacks a property.
General claim :: A claim concerning a substantial number of objects of a certain kind.
Statistical claim :: A general claim that specifies a numerical proportion or percentage.
Universal generalization :: A claim concerning every member of a group, such as “All A are B.”
Negative universal generalization :: A claim that no member of a group has a property, such as “No A are B.”
Counterexample :: A single case that disproves a universal claim or shows that an argument form is invalid.
Reliable source :: A source with a good record of accuracy that is competent, informed, and appropriately positioned to know the facts.
Expert or authority :: A person with relevant specialized knowledge in a genuine field of expertise.
Bias :: A tendency or interest that may distort someone’s judgment or presentation of information.
Conflict of interest :: A personal or professional interest that may interfere with impartial judgment.
Independent sources :: Sources that reached their conclusions separately rather than merely repeating one original source.
Common knowledge :: Information that members of the relevant audience can reasonably be expected to know.
Commonly held belief :: A belief accepted by many people that may nevertheless be false.
Consistency :: A set of claims is consistent when it is possible for all of them to be true together.
Inconsistency :: A set of claims is inconsistent when there is no possible situation in which all of them are true together.
Contradiction :: In the strict sense, a claim that directly denies another claim.
Deductive reasoning :: Reasoning intended to guarantee the conclusion if the premises are true.
Non-deductive reasoning :: Reasoning intended to make the conclusion probable or reasonable without guaranteeing it.
Valid argument :: An argument in which it is impossible for all the premises to be true and the conclusion false.
Invalid argument :: An argument for which at least one possible situation has all true premises and a false conclusion.
Counterexample to validity :: A possible situation or parallel argument with true premises and a false conclusion.
Argument form :: A general pattern created by replacing parts of an argument with variables.
Instance of an argument form :: A particular argument produced by replacing the variables in an argument form with specific content.
Truth-preserving form :: An argument form with no instance containing true premises and a false conclusion.
Formally valid argument :: An argument whose form is valid.
Logically valid form :: A form that is valid solely because of its logical structure.
Sound argument :: A valid argument with all true premises.
Valid but unsound argument :: An argument with valid reasoning but at least one false premise.
Truth versus validity :: Truth applies to individual claims; validity applies to the relationship between an argument’s premises and conclusion.
Implication or entailment :: A set of premises implies or entails a conclusion when the corresponding argument is valid.
Equivalent claims :: Claims that imply each other and therefore have the same truth value in every possible situation.
Logical meaning of “some” :: “Some A are B” means that at least one A is B; it does not imply that some A are not B.
Propositional logic :: The study of argument forms whose variable components are complete propositions.
Logical operator or connective :: An expression that joins or modifies propositions, such as not, and, or, or if-then.
Negation :: The denial of a proposition; symbolized as ¬A and read “not A.”
Double negation :: Two consecutive negations; A and ¬¬A are equivalent.
Conjunction :: A proposition of the form A & B, meaning “A and B.”
Conjunct :: Either component of a conjunction.
Disjunction :: A proposition of the form A ∨ B, meaning “A or B.”
Disjunct :: Either component of a disjunction.
Inclusive disjunction :: “A or B” meaning that at least one is true and possibly both are true.
Exclusive disjunction :: “Either A or B but not both,” symbolized as (A ∨ B) & ¬(A & B).
Conditional :: A proposition of the form A → B, meaning “If A, then B.”
Antecedent :: The first component, A, in a conditional A → B.
Consequent :: The second component, B, in a conditional A → B.
Converse :: The converse of A → B is B → A; it is not generally equivalent to the original conditional.
Contrapositive :: The contrapositive of A → B is ¬B → ¬A; it is equivalent to the original conditional.
Biconditional :: A proposition of the form A ↔ B, meaning “A if and only if B.”
Iff :: An abbreviation for “if and only if.”
Sufficient condition :: A is sufficient for B when A guarantees B; symbolized as A → B.
Necessary condition :: B is necessary for A when A cannot occur without B; symbolized as A → B.
Necessary and sufficient condition :: Each condition guarantees the other; symbolized with a biconditional A ↔ B.
Not both A and B :: Symbolized as ¬(A & B).
Neither A nor B :: Symbolized as ¬(A ∨ B), equivalent to ¬A & ¬B.
A if B :: Symbolized as B → A.
A only if B :: Symbolized as A → B.
A unless B :: Symbolized as ¬B → A.
A provided that B :: Symbolized as B → A.
Double negation rule :: From A infer ¬¬A, or from ¬¬A infer A; valid.
Conjunction rule :: From A and B infer A & B; valid.
Simplification rule :: From A & B infer A, or infer B; valid.
Weakening rule :: From A infer A ∨ B; valid.
Disjunctive syllogism :: A ∨ B, ¬A, therefore B; valid. It also works by eliminating B to conclude A.
Modus ponens :: A → B, A, therefore B; valid.
Modus tollens :: A → B, ¬B, therefore ¬A; valid.
Hypothetical syllogism :: A → B, B → C, therefore A → C; valid.
Formal fallacy :: An error in reasoning caused by using an invalid argument form.
Affirming the consequent :: A → B, B, therefore A; invalid because B could occur for another reason.
Denying the antecedent :: A → B, ¬A, therefore ¬B; invalid because B could still occur for another reason.
Formal proof :: A chain of valid inferences deriving a conclusion from stated premises.
Proof justification :: The inference rule and earlier line numbers that justify a line in a formal proof.
Reduction to absurdity :: A proof method that assumes the opposite of the desired conclusion, derives a contradiction, and rejects the assumption.
Indirect proof :: Another name for a proof by reduction to absurdity.