Deductive reasoning and the argument is “valid”, it is possible for the conclusion to be false (determined to be false with a counterexample or other means). Aristotle started documenting deductive reasoning in the 4th century BC. Deductive reasoning Deductive reasoning, also deductive logic, logical deduction is the process of reasoning from one or more statements (premises) to reach a logically certain conclusion. Deductive reasoning goes in the same direction as that of the conditionals, and links premises with conclusions. If all premises are true, the terms are clear, and the rules of deductive logic are followed, then the conclusion reached is necessarily
Interpretation (logic) valid or tautologous. An "interpretation of a theory" is the relationship between a theory and some subject matter when there is a many-to-one correspondence between certain elementary statements of the theory, and certain statements related to the subject matter. If every elementary statement in the theory has a correspondent it is called a "full interpretation", otherwise it is called a "partial interpretation". The formal language for propositional logic consists of formulas built up from propositional symbols (also called sentential symbols, sentential variables, and propositional variables) and logical connectives. The only non-logical symbols in a formal language for propositional logic are