Final answer:
The phrase "if a, then b" corresponds to a conditional statement, which is a fundamental structure in logical reasoning to establish a logical relation between two propositions. It's an essential part of constructing valid deductive inferences such as disjunctive syllogism, modus ponens, and modus tollens.
Step-by-step explanation:
The phrase "if a, then b" reflects the structure of a conditional statement in the context of mathematical logic. A conditional statement is one that is in the form of an if-then statement, such as "If it rains, then the ground becomes wet." This format is used to establish a logical connection where the truth of the first statement (a) is a sufficient condition for the truth of the second statement (b). The notion of conditional statements is essential in constructing logical arguments and understanding logical inference.
In the logical reasoning, a good deductive inference that derives conclusions from premises is termed a valid inference. The validity of an argument lies in its logical structure, meaning that if the premises are true, the conclusion must necessarily follow. Structural forms of valid deductive reasoning include disjunctive syllogism, modus ponens, and modus tollens. Each of these respects the necessary logical form that guarantees the conclusion given the truth of the premises.
Therefore, the correct form of the statement "if a, then b" is a conditional statement.