Search results
Results From The WOW.Com Content Network
Each proposition (statement that is a thought of the kind expressible by a declarative sentence) [5] of a syllogism is a categorical sentence which has a subject and a predicate connected by a verb. The usual way of connecting the subject and predicate of a categorical sentence as Aristotle does in On Interpretation is by using a linking verb e ...
The immediately inferred proposition is termed the "obverse" of the original proposition, and is a valid form of inference for all types (A, E, I, O) of categorical propositions. In a universal affirmative and a universal negative proposition the subject term and the predicate term are both replaced by their negated counterparts:
The A proposition, the universal affirmative (universalis affirmativa), whose form in Latin is 'omne S est P ', usually translated as 'every S is a P '. The E proposition, the universal negative (universalis negativa), Latin form 'nullum S est P ', usually translated as 'no S are P '.
affirmative proposition A proposition that asserts the truth of a statement, as opposed to negating it. [7] [8] [9] affirming the consequent A logical fallacy in which a conditional statement is incorrectly used to infer its converse. For example, from "If P then Q" and "Q", concluding "P". alethic modal logic
Dictum de omni (sometimes misinterpreted as universal instantiation) [2] is the principle that whatever is universally affirmed of a kind is affirmable as well for any subkind of that kind. Example: (1) Dogs are mammals. (2) Mammals have livers. Therefore (3) dogs have livers. Premise (1) states that "dog" is a subkind of the kind "mammal".
An affirmative (positive) form is used to express the validity or truth of a basic assertion, while a negative form expresses its falsity. For example, the affirmative sentence "Joe is here" asserts that it is true that Joe is currently located near the speaker. Conversely, the negative sentence "Joe is not here" asserts that it is not true ...
For example, by obversion, a universal affirmative statement become a universal negative statement with the predicate term that is the class complement of the predicate term of the original universal affirmative statement.
A sentence can be viewed as expressing a proposition, something that must be true or false. The restriction of having no free variables is needed to make sure that sentences can have concrete, fixed truth values : as the free variables of a (general) formula can range over several values, the truth value of such a formula may vary.