First order logic
In first order logic, reasoning can be done from two points of view: either using syntax alone, or including semantic terms. First order logic is different from propositional logic: In first order logic, there are quantifiers, called for all (written as ) and there is at least one (written as ). Negation, conjunction, inclusive disjunction, exclusive disjunction and implication are all defined the same way as in propositional logic. Because of that, first order logic can be thought of as an extension of propositional logic.