Term logic
In philosophy, term logic, also known as traditional logic or Aristotelian logic, is a loose name for the way of doing logic that began with Aristotle and that was dominant until the advent of modern ...
Immediate inference
An immediate inference is an inference which can be made from only one statement or proposition. For instance, from the statement "All toads are green." we can make the immediate inference that "No to...
Syllogism
A syllogism (Greek: συλλογισμός syllogismos, "conclusion, inference") is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two or more propositions that ar...
Main contention
In both formal and informal logic, a main contention or conclusion is a thought which is capable of being either true or false and is usually the most controversial proposition being argued for. In re...
Modus ponens
In propositional logic, modus ponendo ponens (Latin for "the way that affirms by affirming"; often abbreviated to MP or modus ponens) or implication elimination is a valid, simple argument form and ru...
Subalternation
Subalternation is an immediate inference which is only made between A (All S are P) and I (Some S are P) categorical propositions and between E (No S are P or originally, Not every S is P) and O (Some...
Boole's syllogistic
Boolean logic is a system of syllogistic logic invented by 19th-century British mathematician George Boole, which attempts to incorporate the "empty set", that is, a class of non-existent entities, su...
Boole's syllogistic - Wikipedia
Superaltern
An immediate inference is an inference which can be made from only one statement or proposition. For instance, from the statement "All toads are green." we can make the immediate inference that "No to...
Prosleptic syllogism
A prosleptic syllogism is a class of syllogisms that use a prosleptic proposition as one of the premises. The term originated with Theophrastus of Eresus, although Aristotle did briefly mention such ...
Prosleptic syllogism - Wikipedia
Categorical proposition
In logic, a categorical proposition, or categorical statement, is a proposition that asserts or denies that all or some of the members of one category (the subject term) are included in another (the p...
Contrary (logic)
Contrary is the relationship between two propositions when they cannot both be true (although both may be false). Thus, we can make an immediate inference that if one is true, the other must be false...
Contrary (logic) - Wikipedia
Baralipton
In classical logic, baralipton is a mnemonic word used to memorize a syllogism. Specifically, it is when the first two propositions thereof are general, and the third particular; the middle term being...
A priori and a posteriori
The terms a priori ("from the earlier") and a posteriori ("from the later") are used in philosophy (epistemology) to distinguish two types of knowledge, justification, or argument:There are many point...
Square of opposition
In the system of Aristotelian logic, the square of opposition is a diagram representing the different ways in which each of the four propositions of the system is logically related ('opposed') to each...
Square of opposition - Wikipedia
Modus tollens
In propositional logic, modus tollens (or modus tollendo tollens and also denying the consequent) (Latin for "the way that denies by denying") is a valid argument form and a rule of inference.The firs...
Law of thought
The laws of thought are fundamental axiomatic rules upon which rational discourse itself is often considered to be based. The formulation and clarification of such rules have a long tradition in the ...
Good and necessary consequence
The phrase good and necessary consequence was used more commonly several centuries ago to express the idea which we would place today under the general heading of logic; that is, to reason validly by ...
Principle of explosion
The principle of explosion (Latin: ex falso quodlibet, "from a falsehood, anything follows", or ex contradictione sequitur quodlibet, "from a contradiction, anything follows"), or the principle of Pse...
Premise
A premise or premiss is a statement that an argument claims will induce or justify a conclusion. In other words: a premise is an assumption that something is true. In logic, an argument requires a set...
Triangle of opposition
In the system of Aristotelian logic, the triangle of opposition is a diagram representing the different ways in which each of the three propositions of the system is logically related ('opposed') to e...
Syncategorematic term
In scholastic logic, a syncategorematic term (syncategorema) is a word that cannot serve as the subject or the predicate of a proposition, and thus cannot stand for any of Aristotle's categories, but ...
Problem of multiple generality
The problem of multiple generality names a failure in traditional logic to describe certain intuitively valid inferences. For example, it is intuitively clear that if:then it follows logically that:T...
Dictum de omni et nullo
In Aristotelean logic, dictum de omni et nullo (Latin: "the maxim of all and none") is the principle that whatever is affirmed or denied of a whole kind K may be affirmed or denied (respectively) of a...
Organon
The Organon (Greek: Ὄργανον, meaning "instrument, tool, organ") is the standard collection of Aristotle's six works on logic. The name Organon was given by Aristotle's followers, the Peripatetics. The...
Disjunctive syllogism
In classical logic disjunctive syllogism (historically known as modus tollendo ponens) is a valid argument form which is a syllogism having a disjunctive statement for one of its premises.In proposit...
Port-Royal Logic
Port-Royal Logic, or Logique de Port-Royal, is the common name of La logique, ou l'art de penser, an important textbook on logic first published anonymously in 1662 by Antoine Arnauld and Pierre Nicol...
Hypothetical syllogism
In classical logic, hypothetical syllogism is a valid argument form which is a syllogism having a conditional statement for one or both of its premises. In propositional logic, hypothetical syllogism ...
Predicable
Predicable (Lat. praedicabilis, that which may be stated or affirmed, sometimes called quinque voces or five words) is, in scholastic logic, a term applied to a classification of the possible relation...
Prior Analytics
The Prior Analytics (Greek: Ἀναλυτικὰ Πρότερα; Latin: Analytica Priora) is Aristotle's work on deductive reasoning, which is known as his syllogistic. Being one of the six extant Aristotelian writ...
Prior Analytics - Wikipedia
Law of identity
In logic, the law of identity is the first of the three classical laws of thought. It states that “each thing is the same with itself and different from another”. By this it is meant that each thing ...
Inverse (logic)
In logic, an inverse is a type of conditional sentence which is an immediate inference made from another conditional sentence. Any conditional sentence has an inverse: the contrapositive of the conver...