Glossary


Rationale > Glossary

A priori	A priori knowledge consists of propositions that are knowable independently of experience of the world.
A posteriori	A posteriori knowledge consists of propositions that are known on the basis of empirical experience of the world.
Appeal to illegitimate authority	A fallacious form of reasoning which asks you to accept something asserted by someone who is not an expert in the area in question. Alternatively, a bad pattern of reasoning that asks you to accept the word of a suitably qualified expert in some matter that is widely agreed to be contentious or disputed by other experts in the field. Latin name: ipse dixit.
Appeal to pity	A fallacy involving an attempt to get you to accept a claim out of sympathy for the person offering it. Latin name: ad misericordiam.
Appeal to popularity	Fallacious reasoning that attempts to get you to accept a claim on the basis that it is widely thought to be true. Latin name: ad populum.
Argument	An argument is a structured set of reasons or objections bearing upon some claim.
Argument from ignorance	The fallacy of reasoning that since something hasn't been proven false, then it must be true. Latin name: ad ignorantiam.
Begging the question	A fallacious circular form of reasoning that relies on a premise that would only be accepted by someone who was already convinced that the conclusion was true. Latin name: petitio principii.
Claim	A claim is a statement that someone puts forward as true.
Coherence theory of truth	True statements are those that cohere with our other justified beliefs.
Coincidental correlation	The fallacy of reasoning that assumes that based solely on the fact that X happens after Y we can conclude that Y must cause X. Latin name: post hoc ergo propter hoc.
Conclusion	A conclusion is what follows from an argument. It is that which the premises support.
Correspondence theory of truth	The theory that true statements are those that correspond to the way the world actually is.
Deductive	A deductive argument is one where the premises guarantee the truth of the conclusion. If the premises are true, it's impossible that the conclusion could be false.
Empiricism	Empiricism is the view that all knowledge of the world is derived from sense experience is our source of knowledge about the world.
Fallacy	A fallacy is a common pattern of reasoning that is always or at least commonly bad.
False dilemma	Fallacious reasoning that presents an either/or choice when in fact other options exist.
Hypothesis	A hypothesis is an educated guess based on observation.
Inductive	An inductive argument is one where the premises support the probable truth of the conclusion. If the premises are true, the conclusion is unlikely to be false. Inductive arguments purport to extend our knowledge, i.e., to draw a conclusion which goes beyond the information contained in the premises.
Knowledge	Knowledge can be defined as justified true belief. This concept is knowledge is suited to propositions.
Objection	An objection provides evidence that another claim is false.
Objective	Roughly speaking, 'objective' means 'independent of the individual'. Metaphysically objective things are those which exist independently of being experienced. Epistemically objective statements are those which have a truth value decided by public methods.
Personal attack	The fallacy which involves an attack on the person offering a claim, rather than engaging with the substance of what he or she says. Latin name: ad hominem.
Pragmatic theory of truth	True statements are those that work for us and meet our needs better than their alternatives.
Premise	A premise is a statement providing support or evidence for the conclusion of an argument.
Proposition	A statement that affirms that something is true or false.
Reason	A reason provides evidence that another claim is true.
Slippery Slope	A pattern of reasoning that presents a chain of increasingly dire consequences as following inevitably from accepting some claim. This form of reasoning is very often - but not always - a fallacy.
Semantics	Semantics is concerned with the meaning of words and sentences. When we are interesting in semantics we're interested in the content or meaning of sentences, often in relation to their truth and falsehood.
Sound	A sound argument is one which is both valid in form and has true premises.
Subjective	Roughly speaking, 'subjective' means 'pertaining to the individual, or peculiar to a particular personal perspective on the world'. Metaphysically subjective things are those whose existence depends on their being experienced. Epistemically subjective statements are those which have a truth value decided by reference to individual perspectives.
Syntax	Syntax is concerned with the structure of language, particularly getting the words of a sentence in the right order. When we are interested in syntax we are interested in the logical or grammatical form of sentences, rather than what they refer to or mean.
Testability	Testable claims prohibit particular events or occurrences. Untestable claims prohibit nothing.
Theory	A theory summarizes a hypothesis or a group of hypotheses that have survived repeated testing.
Valid	A valid argument is one that has a form such that the premises guarantee the truth of the conclusion, i.e., if the premises are true, the conclusion must be true.

This material has been developed independently of the International Baccalaureate, which in no way endorses it.

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