Modus tollens (Latin for "mode that, by denying, denies", Chinese:"否定前提法") is a form of valid argument in classical logic. It is a deductive argument form that takes the following form: - If P, then Q. - Not Q. - Therefore, not P. In other words, if a statement implies another statement, and the second statement is false, then the first statement must also be false. For example: - If it is raining, then the ground is wet. - The ground is not wet. - Therefore, it is not raining. Modus tollens is a very useful form of argument, and it is used in many different fields, including mathematics, philosophy, and law. It can be used to prove theorems, disprove hypotheses, and identify logical fallacies. Here is another example of a modus tollens argument: - If I am a bird, then I can fly. - I cannot fly. - Therefore, I am not a bird. Modus tollens is a valid form of argument, but it is important to note that it is only as valid as its premises. If either of the premises is false, then the conclusion may also be false. For example: - If it is raining, then the ground is wet. - The ground is wet. - Therefore, it is raining. This argument is not valid because the second premise is false. The ground could be wet for other reasons, such as someone spilling a bucket of water. Overall, modus tollens is a valuable tool for logical reasoning. However, it is important to use it carefully and to be aware of the potential for fallacies. # References ```dataview Table title as Title, authors as Authors where contains(subject, "modus tollens") or contains(subject, "Modus Tollens") ```