Glossary

a posteriori – something that is known after experience.

a priori – something that is known without experience (eg, by virtue of definitions or logical necessity).

All-purpose premise – a premise that supposedly fills a gap in reasoning from A to B of the form ‘If A, then B’ or equivalent. It should not be used.

Antecedent – part of a conditional. In “If A, then B”, A is the antecedent

Argument – a reasoned attempt to support, justify, or prove a conclusion via a series of statements.

Cogent – an argument is cogent if it has acceptable premises and provides strong or complete support for its conclusion.

Compund Sentence/Statement – a sentence/statement that makes more than one declaration.

Conclusion – a statement in an argument that is being supported by other statements.

Conditional – a statement of the form “If A, then B” or equivalent

Conjunct – simple statement that forms part of a conjunction.

Conjunction – two simple statements joined with ‘and’ or something equivalent.

Consequent – part of a conditional. In “If A, then B”, B is the consequent

Contingent (truth) – something that happens to be, but did not have to be. A contingent truth could have been false.

Contradiction – when something is being both asserted and denied.

Convergent support – when two or more premises each independantly support a conclusion.

Declarative Sentence – a sentence that expresses the claim that something is true. They can be true or false.

Deductive Validity – an argument is deductively valid when it is impossible for its premises to be true and its conclusion false.

Disjunction – two simple statements joined with an ‘or’ or something equivalent.

Disjunt – a simple statement that forms part of a disjunction

Exclusive ‘or’ – when a disjunction is asserting that exactly one of the disjuncts is true

Hidden Premise – a premise that is not stated explicitly, sometimes because it is obvious, sometimes because it is controversial.

Implied Conclusion – a conclusion that is not stated explicitly but that the arguer intends for you to reach.

Inclusive ‘or’ – when a disjunction is asserting that at least one of the disjuncts are true

Infer – to deduce or conclude.

Inference – the reasoning connecting one or more premise to a conclusion or sub-conclusion.

Inference Indicator – a word in natural language that indicates where an inference is being made, such as ‘because’, ‘as’, ‘since’, ‘therefore’, ‘so’, ‘thus’ etc.

Linked support – when two or more premises combine to create an inference to a conclusion (no individual support).

Modal Expression – words like ‘necessarily’, ‘must’, ‘has to’, ‘must not’, ‘cannot’, ‘possibly’, ‘probably’ etc. These words have multiple functions in natural language.

Necessary (truth) – something that must be. A necessary truth could not have been false.

Premise – a statement in an argument that supports other statements.

Provisional Premise – a premise that is assumed to be true for the sake of argument but may not be believed or known to be true.

Simple Sentence/Statement – a sentence/statement that makes one declaration.

Sound – an argument is sound if it has true premises and is deductively valid.

Standardising – a process of transforming arguments from natural language into their logical order.

Statement – a declaration. May be all or part of a sentence.

Sub-conclusion – a statement in an argument that is both supported by other statements, and itself supports other statements.

Support – a relationship between premises and conclusions. A good argument is said to have premises that support its conclusion.

Truth – a property of statements. A statement is true if the world actually is how the statement claims that it is.

Validity – see deductive validity.